1. In brief – what is preheat temperature, what is interpass temperature.
2. Where exactly on metal surface should these temperatures be checked while welding?
3. How to check them?
4. Difference between the two.

Please note that most of the content of this article, like a bulk of this website, is centred around ASME Section IX. Also, the relevance of some of the ideas discussed here might be more to CS and LAS metals.

What Are Preheat And Interpass Temperatures

Preheat: is the application of heat to a weld joint before start of welding. It serves the purpose of slowing down the rate of cooling of weldment; thus allowing the hydrogen in the weld metal to diffuse out and thus avoid cold cracking. Preheat temperature is the minimum temperature specified on WPS which the welder must follow in order to ensure preheat.  

Interpass temperature: During the welding, before start of each pass – temperature of weld joint must be checked, and regulated according to the WPS. The purpose of this monitoring is to maintain influence on the microstructure/ properties of the weld metal.

Note: This article does not explore what effect interpass temperature has on the properties of weld metal.

Where Should Preheat And Interpass Temperature Be Checked?

This question often does rounds in my shops. Where should preheat and interpass temperatures be checked?

On the weld metal? On the surface of weld edge preparation (WEP)? On the face of the joint? How much away from the edge? Let’s see.

Preheat Temperature

The definition of this term, given at QG-109 of Sec IX, contains pointers to this question. The definition indicates that for single pass welds – the preheat temperature is the temperature of the weld edge just prior to welding. In other words, the temperature is required to be checked on weld edge preparation (WEP).

The definition goes on to say that, for multi-pass welds, preheat temperature is the temperature in the section of the previously deposited weld metal, just before each pass is to be deposited. That is, the temperature is to be checked on the weld metal.

This rule however, it must be noted, is not the same as that adopted by the ISO codes. The ISO 13916 specifies that if the thickness of base metal is less than 50 mm, the temperature must be checked at a distance of 4T from the WEP, where T = thickness of base metal, but need not be more than 50 mm. If the base metal thickness exceeds 50 mm, the temperature must be checked at a distance of at least 75 mm away from the WEP in all directions, unless something else is specifically agreed with inspector/ customer.

The ISO 13916 also specifies that the temperature should be checked on the opposite face of the face which his being exposed to the source of heating, as far as possible. If not possible, temperature may be taken after the removal of source of heat (imagine a gas flame) after elapse of some time – which is to be at least 2 min/25 mm of base metal thickness.

Interpass Temperature

The Section IX definition of interpass temperature says that it is the temperature in the previously deposited weld metal or adjacent base metal (typically within 25 mm) just before laying of next pass. In other words, the temperature is to be checked on the base metal itself.

The ISO 13916 specifies the same location as the preheat temperature, for interpass temperature too.

I have summarized the above rules in the following table:

How To Check Preheat & Interpass Temperatures

Codes do not specify any mandatory method for checking preheat and interpass temperature. So, any suitable method may be used. A commonly used method in the industry is thermos-chalks (also called as thermal crayons in some places).

A chalk comes with a rating of, say 150°C. If it is rubbed on a metal surface having any temperature above 150°C, the chalk will melt and evaporate. So chalks are a good tool for confirmation checks. Welder can keep a chalk for preheat and another for interpass in his pocket, and check periodically to confirm that his weld meets temperatures specified on the WPS. Chalks are a cool method of checking temperature for production welds.

Other more sophisticated methods include non-touch equipment such as pyrometers, thermocouples, etc. In these methods, a reading is generally displayed on the digital screen; and are a less fussy, slightly faster, and more accurate way of measuring the temperatures. Specially, if you are making a qualification test coupon, these methods – in my opinion – are a better way to check the temperature as you can record the precise value of preheat/interpass for each pass.

Difference Between Preheat And Interpass Temperature

Although Section IX lays out definition for both these terms at QG-109, the difference is not so obvious to the layman eye. Both definitions sound somewhat similar. Let’s see if we can make things a little clearer.

A good way of distinguishing between the two is to remember that preheat is specified as a minimum temperature while interpass temperature is specified as a maximum temperature. That is, throughout the duration of welding, the temperature in the weld region must not fall below preheat temperature, before start of any pass. Also, throughout the duration of welding, the temperature in the weld region must not be above interpass temperature, before start of any pass.

Another difference between the two is that while preheat Is an essential variable (and hence always applicable), interpass is a supplementary essential variable (and so – applicable only when impact toughness is a consideration).

Some confusion does arise when people accustomed to ASME Codes start using other codes. The understanding in above 2-3 paras is not found uniformly in other codes. For example, some codes/ standards specify that preheat is the temperature before start of first pass of the weld joint. Any temperature measured immediately before start of any of the subsequent passes is termed as interpass temperature.

Also, in other codes, the interpass may be specified as a minimum value too (this is generally equal to the preheat temperature). And so, in some WPSs written to AWS codes, one may find both minimum and maximum interpass temperatures specified on the WPS.

Effectively, the physical work on the ground would be the same with both the ASME WPS as well as the AWS WPS. Only, the semantics are different.

This website talks a fair bit on the subject of preheat and interpass temperatures for procedure qualifications to ASME Sec IX. One of main articles on this is this.

That is all. Thanks for reading. Comment below if you would like to say something.

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This article explores a few aspects related to SWPSs.

Please note that most of the discussion herein is pertinent to ASME BPVC Section IX only.

What is a SWPS?

Ordinarily, Section IX requires that each organization shall qualify their own WPS before taking up production work. That is, an organization cannot borrow (or steal) WPS qualified by another organization and use it directly. Section IX has always been very clear on this (reaffirmed by several interpretations) that work of WPS qualification must be done by the organization itself, and cannot be subcontracted to another.

Assume that you are trying to qualify P-No. 1 + P-No. 1 combination welded with ER70S-2 at root and E7018-1 for fill passes, over a thickness range of 3/16 inch (5 mm) to 8 inches (200 mm). This qualification, regardless of where it is done, will throw up a PQR/WPS that will be qualitatively same anywhere. Probably recognizing that such common qualifications need not be repeated; an organization should be able to start production welding right away if it had access to an already made WPS, and the organization could demonstrate ability to competently use that WPS. Thus was born the concept of SWPSs.

Who Prepares SWPSs?

SWPSs, short for Standard Welding Procedure Specifications, are developed by American Welding Society (AWS), and they are available on pubs.aws.org for anyone wanting to buy. Basically, one can buy a SWPS and start using it on job straightaway without having to do a procedure qualification. There are some rules that need to followed however. These rules, which we will discuss in brief later in this article, are contained in Article V of Section IX.

The data on SWPSs is derived from PQRs maintained by AWS. The PQRs are not shared with the buyer of SWPS. The work of qualifying these PQRs and preparation of SWPSs is done following a rigorous set of rules. It can therefore be safely taken for granted that the welds made with these SWPSs will have a high probability of successful application.

When Can A SWPS be Used?

Since the year 2000 onwards, Section IX permits the use of SWPS instead of the regular WPSs. So, SWPS may be used in fabrication work for any construction code (or referring standard/ specification) that invokes use of Section IX, unless specifically prohibited by that code (or referring standard/ specification).

SWPSs, however, cannot be used for applications requiring impact toughness – as this is prohibited by Section IX itself.

Conditions For Using SWPS

SWPSs may seem like a godsend at first; however, the matter is not as straightforward. Section IX allows use of SWPS but under some conditions that are defined at Article V of Section IX. The Article V comprises of some administrative requirements, besides welding and testing of a Demonstration coupon, followed by documentation and certification of the resulting Documentation Record.

Once an organization procures the SWPS from pubs.aws.org, the Article V requires the user organization to fulfil following requirements before putting the SWPS to use in production welds:

1. Name of organization shall be entered on the SPWS at relevant place.
2. The relevant person of the organization shall sign and date the SWPS.
3. The governing code or specification (such as ASME Section III NB or ASME B31.3, or a contract document etc.) according to which welding needs to be done shall be mentioned in the SWPS (As discussed elsewhere in this article, this entry can be revised without having to redo the demonstration).
4. Carry out a demonstration coupon welding and testing. The variables used in making this coupon, the tests done and results shall be recorded. This document shall be certified by the user organization. This work must be done before the SWPS can be used for production purposes.

Demonstration Coupon

The user organization is required to make a groove weld coupon using the SWPS.

The actual value of variables used in preparation of this coupon must be recorded (a recommended format is given at QW-485). It should be kept in mind by the code user that these values should fall within the range specified on the SWPSs. These variables, enumerated under QW-510, are mostly same as the usual essential and non-essential variables for manual welding processes. Following the welding, testing of coupon needs to be done, which is defined under QW-510.

The testing comprises of: i) visual examination, and, ii) mechanical testing or volumetric examination. The method of testing and acceptance criteria of these tests are the same as those for performance qualifications (given at Article III of Section IX).  In essence, the demonstration coupon is quite similar to a performance qualification. The tests done and their results must be recorded along with variables used.

The Demonstration coupon is required primarily to establish that the user organization is capable of using the SWPS. This demonstration is a mandatory requirement, and must be carried out carefully to ensure that the SWPS is fully followed. The identity of Supporting Demonstration must be noted on the SWPS before the SWPS can be used. Like a PQR, the Supporting Demonstration must be available for review by inspector, whenever asked.

Are SWPSs useful?

Essentially, a SWPS saves the trouble of doing the mandatory bend tests and tension tests that are required for the usual procedure qualification. If your company has X-ray facility, you can get done with the demonstration coupon by simply doing visual examination and radiography – completely avoiding the mechanical testing. However, SWPSs come at a price. Last I checked, an ordinary SWPS costs nearly 250 USDs. So, it is not exactly cheap. It is very difficult to find pirated versions on the internet either. Smaller private-run organizations probably find doing the mechanical testing (for doing the regular WPS qualification) cheaper.

But for big organizations, where this cost does not mean much and who want to avoid the time delay in preparation of test specimens and mechanical testing, SWPS are surely useful.

Technically though, in the grand scheme of life – SWPSs have little to offer to the code user. When using a SWPS, you are rigidly bound to follow it. Code users are not allowed to make changes to a SWPS. On the other hand, if you qualify your own PQR, you own that document. Changes are allowed to be made to the resulting WPS according to your needs.

The demonstration coupon of a SWPS can also be utilized to qualify the welder simultaneously, since testing required for performance qualification gets covered within that of demonstration coupon. All that one needs to do is write the WPQR, in addition to the Demonstration record. This saves some time and resources.

Frequently Asked Questions

Q1: A SWPS permits both with and without PWHT. The demonstration coupon should be heat treated or left as-welded?

A1: If the demonstration coupon has been left as-welded, the SWPS can be used for welds in as-weld condition only (i.e. must not be heat treated). If the demonstration coupon has been heat treated according to the PWHT listed on SWPS, the SWPS can be used for production welds in PWHT condition only (i.e. cannot be left as-welded). In short, when a SWPS permits both with and without PWHT, it essentially means two demonstration coupons should be made – one with PWHT, and one without.

Q2: Can a SWPS be revised?

A2: No, unlike ordinary WPSs – SWPS cannot be revised by users (AWS can revise them of course), except that the governing code or specification, which is required to be listed on a SWPS before using it, can be revised without further demonstration.

However, the code does allow the user to supplement a SWPS by attaching additional instructions with a SWPS that might help the welder in achieving the desired quality of weld. However, these instructions must not violate the SWPS in any way, and must be within the boundaries set by SWPS.

For example, the SWPS specifies J-groove and U-groove, and single side welding. The supplemental instruction sheet may restrict the welder to use only J-groove (since J-groove is obviously permitted by SWPS), but may not ask the welder to use a groove design other than the two mentioned on SWPS (double V-groove with back-grinding, for example).

Q3: Can a SWPS be supplemented by a PQR to enhance its scope?

A3: No. This is prohibited by Article V of Section IX. As mentioned in Q2 above, it is not allowed to revise a SWPS at all, except for changing the governing code or specification.

Q4: Can a user make some minor changes in non-essential variables on a SWPS?

A4: No. SWPS is a ready-made document, prepared by AWS. Users are not allowed to change it. Once issued to a welder, he is expected to comply with it in full. Also, there is no such thing as non-essential variables on a SWPS. All variables are equally essential.

The demonstration coupon is thus a chance for the organization to satisfy itself that it is able to follow the SWPS in full. If it is not able to follow the SWPS (may be for justifiable reasons), then perhaps SWPS is not the right path for that organization; a regular WPS should be qualified instead.

Q5: A SWPS lists multiple processes (e.g. GTAW at root, followed by SMAW for fill). Can a user use only the GTAW part and ignore the rest?

A5: No. When a multiple-process SWPS is used, all processes mentioned on SWPS must be used in the order and manner specified on SWPS.

Q6: Can a joint be made partly with a SWPS and partly with a regular WPS?

A6: No. This is not permitted by Section IX (QW-540(d)).

For example, a SWPS specifies welding with GTAW only. A company wants to use GTAW for root, and SMAW for remaining thickness. The company wants to use SWPS for root welding, and its own regular WPS for SMAW portion. Is it permitted to do this?

No, this is prohibited by Section IX.

A SWPS therefore, before its adoption, should be carefully assessed by the user. As in above case, if the company wants to use both GTAW and SMAW in a joint, they should consider using a different SWPS or follow the regular route of qualifying a WPS and use it.

In any case, the demonstration coupon offers an apt opportunity to not just the user organization but also the inspector, to judge whether the organization is capable of using the SWPS in full, in relation to all variables, or not.

Q7: Is it mandatory to certify the Supporting Demonstration record?

A7: The Supporting Demonstration holds a similar status as the regular Procedure Qualification Record (PQR). As such, Section IX requires that the user organization welds, tests the demonstration coupon, and certifies the resulting Demonstration Record. As such, the recommended format of Section IX (at QW-485) for recording Demonstration lists a certifying statement at the bottom.

Q8: Can the demonstration coupon be welded and tested in parallel to the use of SWPS on job?

A8: No. Welding, Testing, and Certification of demonstration coupon must be done before SWPS can be used for production welding. This is given at QW-540 (f).

Q9: Can SWPS procured by an organization be used by sister units of that organization falling within the same corporate ownership?

A9: Although Section IX says nothing explicitly on this, and no interpretation seems to be available either, it can be reasonably assumed that the rules applicable for regular WPS are intended for SWPS as well. In the writer’s opinion, provided the quality programs of the sister units address the operational control of the procedure qualifications, SWPSs can be shared within them.

Q10: Is a separate demonstration coupon required for every SWPS?

A10: No. Once an organization demonstrates a SWPS, similar SWPSs can be used without further demonstration. Similar SWPS means that it must have same process, P-numbers, PWHT condition, F-number, mode of transfer (i.e. globular/pulsed/spray etc.), F-number, preheat. These variables (within which the new SWPS must lie) are defined at QW-520.

That is all. Thanks for reading. Feel free to share your thoughts in comments section below.

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A. Introduction

The line 9 of last paragraph of NB-2420 of BPVC Section III NB says that use of controlled chemical composition is only permitted for carbon steel and low alloy steel consumables. This rule poses significant difficulty in implementation, especially in fabrication of covered electrodes of non-CS and non-LAS composition. This article explores the following aspects of this rule:

1. What does the rule say in 2023 edition?
2. What difficulties does this rule pose in industry?
3. Deliberations done on the subject in BPV III SG MFE committee in the past three years.
4. What did the earlier editions of Section III NB say on the subject?
5. What do the other international codes say on the subject?
6. Case for revision in code.
7. Proposed code changes to para NB-2420.

B. What Does the Rule Say in 2023 Edition?

Line 9 in the last paragraph under NB-2420 states that ‘use of controlled chemical composition is permitted only for carbon and low alloy steel consumables.

Note: The term ‘the rule’ in all subsequent paragraphs of this article refers to this stipulation.

This means that only one wet mix of covering ingredients and one heat of core wire can be permitted in the manufacture of one lot of non-CS and non-LAS electrodes (e.g. stainless steel covered electrodes, nickel alloy covered electrodes, etc.).

This rule was introduced in its’ current form in 2017 edition of Section III NB for the first time, and has remained unchanged in this regard in all subsequent editions.

The last para of NB-2420 begins with the line that ‘when filler metal of controlled chemical composition (as opposed to heat control) is used, each container shall be identified…’ etc. etc. The phrase ‘as opposed to heat control’ here gives an indication that the discussion is about consumables that are identified by heat number, as opposed to those identified by dry mix/ wet mix numbers etc. This points towards bare rods/ wires that are used with OFW/SAW/GTAW/PAW/GMAW/EGW processes and the core wire of SMAW electrodes.

It is presumed that the line 9 under NB-2420, which states that ‘the use of chemical composition is only permitted for carbon and low alloy steel consumables’, is not to be read in isolation; and is in fact applicable only to the bunch of consumables referred to by the opening statement of the paragraph.

The language used in the earlier editions of code gives credence to this thinking, as further explained in para ‘E’ below.

The above discussion gives an impression that the said rule is not applicable to covering flux of SMAW electrodes. However, multiple interpretations – as explained in detail in para ‘D’ below, unequivocally convey that the rule is in fact applicable to covering flux of SMAW electrodes also.

Thus, a supplier of non-CS and non-LAS electrodes (such as SS & Ni-alloy electrodes) is constrained to use only one wet mix in the manufacture of a lot of electrodes.

C. Difficulties in Implementation in Industry

This section describes how SMAW electrodes are generally manufactured, and how the above-discussed rule poses a difficulty in manufacture of non-CS & non-LAS electrodes.

C.1. In Brief – How Covered Electrodes Are Manufactured

Covered electrodes are generally manufactured by the following process:

1. Prepare dry mix by mixing together dry constituent powders in an appropriate proportion (this formulation is typically a trade secret of electrode manufacturer). Dry mix is the name given to the quantity that is mixed in a vessel in one go. Typically, dry mix capacity of most suppliers varies between 500 – 700 kg. Number of dry mixes used depends on the total order quantity needing to be made.
2. Divide dry mix(es) into smaller parts called wet mixes. The term wet mix is the name given to the combination of liquid binder and the portion of dry mix mixed in a vessel in one go. Typically, wet mix capacity of most suppliers varies between 100 kg – 200 kg.
3. Feed wet mix and bare cut lengths of core wire in an extrusion machine, which ejects finished electrodes on the other side.

NB-2420 requires all covered electrodes (used with SMAW process) to be of lot class C3. In the matter of covering flux, the C3 requirement (defined under SFA-5.01 of Section II-part C) entails using one wet mix only; alternatively, several wet mixes can be used – provided all are of controlled chemical composition. This phrase – controlled chemical composition – requires that chemistry checks should be done on all wet mixes to assure that all within a lot are equivalent. If the composition of all wet mixes is equivalent (i.e. the chemical composition is controlled), then the total collective electrode quantity produced from all wet mixes can be designated as a single lot.

Use of multiple wet mixes permits suppliers to accommodate large quantity under a lot. Considering that NB-2400 requires lot qualification of each lot, doing this reduces the volume of testing that the supplier is required to do.

C.2 How Is Controlled Chemical Composition Useful?

The allowance of controlled chemical composition is a useful tool to avoid large volume of unnecessary testing, while also assuring homogeneity in properties across the entire lot of electrodes. If the composition of all wet mixes falls within a range (this range is laid down by the supplier himself), then the resulting electrodes from all wet mixes would also have homogeneity in properties. Thus goes the intent behind this liberty.

C.3 Nature of The Problem at Hand

Most suppliers have a wet mix capacity not exceeding 200 kg. Flux forms around 30-35% of the total electrode weight. Thus, one wet mix results in finished electrodes of about 600 kg.

If only one wet mix is permitted in a lot of non-CS and non-LAS electrodes, the typical lot size gets restricted to about 600 kg. In other words, the required testing would need to be done for each 600 kg of electrodes.

A fabricator who procures 30 tons of electrode would need to do the required testing 50 times! This is an inordinately excess amount of testing. For Ni/Cu/Cu alloys, 50 batch tests under an inspection agency, and involving an accredited lab – becomes an economically prohibitive exercise, not to mention time, resources, and effort, without addition of significant value to the outcome.

D. Interpretations On The Subject

A number of interpretation requests have been asked from ASME on this subject. A few are reproduced below.

D.1. Interpretation request 21-1772, 22-1718

Background info:

The last paragraph of NB 2420 begins by saying “…when filler metal of controlled chemical composition (as opposed to heat control) is used…”. The paragraph goes on to say that “use of controlled chemical composition is only permitted for carbon and low alloy steel consumables.” The words “as opposed to heat control” at the beginning of the paragraph seem to indicate that this restriction on use of controlled chemical composition for only CS & LAS consumables is applicable only to consumables used with processes such as SAW, GTAW, PAW, GMAW etc.

Question 1: Does NB-2420 permit the use of controlled chemical composition for core wire of a nickel alloy electrode of Lot Class C3?

Reply 1: No.

Question 2: Does NB-2420 permit the use of controlled chemical composition for covering flux of a nickel alloy electrode of Lot Class C3?

Reply 2: No.

This interpretation was discussed at length in the MF&E subgroup virtual meeting too, on August, 09, 2023. The discussion in the meeting indicated that in the opinion of the MF&E subgroup – the rule is in fact applicable to covering flux of nickel alloy covered electrodes.

D.2. Interpretation request 23-2629

Question: Does NB-2420 permit the use of controlled chemical composition for lot classification C3 (Covered electrodes) & S2 (Fully metallic welding consumables) of Stainless Steel welding consumables?

Reply: No.

D.3. Interpretation request 23-2663

Background info:

As per last para of NB-2420: “In all cases, when filler metal of controlled chemical composition (as opposed to heat control) is used, each container of welding consumable shall be coded for identification and shall be traceable to the production period, the shift, the manufacturing line, and the analysis of the steel rod or strip. Carbon, manganese, silicon, and other intentionally added elements shall be identified to ensure that the material conforms to the SFA or user’s material specification. The use of controlled chemical composition is only permitted for carbon and low alloy steel consumables. Tests performed on welding material in the qualification of weld procedures will satisfy the testing requirements for the lot, heat, or combination of heat and batch of welding material used, provided the tests required by Article NB-4000 and this sub-article are made and the results conform to the requirements of this Article.”

This para talks about Carbon & Low alloy steel and do not provide clarity on other materials like Stainless Steel with regard to the use of controlled chemical composition during manufacture of welding consumables.

Question: Does NB-2420 permit use of a chemically controlled weld consumable that is not carbon or low alloy steel?

Reply: No.

Conclusion: All the above interpretation requests have elicited the response from Section III committee that the use of controlled chemical composition is in fact not permitted for non-CS and non-LAS consumables.

E. What Did the Earlier Editions Say?

While there is no exact equivalent of the rule in any of the editions dated 2015 and before, the clauses that come closest to the rule are NB-2420(e), (f). The clauses are reproduced below:

Extract from NB-2420 of Section III NB, 2015 edition…

‘(e) A heat of bare electrode, rod, wire, or consumable insert is defined as the material produced from the same melt of metal.

(f) Alternatively, for carbon and low alloy steel bare electrode, rod, wire, or consumable inserts for use with SAW, OFW, GMAW, GTAW, PAW, and EGW processes, a heat may be defined as either the material produced from the same melt of metal or the material produced from one type and size of wire when produced in a continuous period [not to exceed 24 hr and not to exceed 100,000 lb (45,000 kg)] from chemically controlled wire, subject to requirements of (1), (2), and (3) below.

(1) For the chemical control of the product of the rod mill, coils shall be limited to a maximum of one splice prior to processing the wire. Chemical analysis shall be made from a sample taken from both ends of each coil of mill-coiled rod furnished by mills permitting spliced coil practice of one splice maximum per coil. A chemical analysis need be taken from only one end of rod coils furnished by mills prohibiting spliced coil practice.

….’

Following can be reasonably inferred from the above paragraphs:

1. Clauses NB-2420(e), (f) almost mirror the definition of heat and the alternative: controlled chemical composition for fully metallic consumables, given at para 3.4 and 3.5.2, respectively, in SFA-5.01 of ASME Section II Part C.
2. Clause NB-2420(f) permits use of controlled chemical composition (as an alternative to the definition of heat in point NB-2420(e)), but only for consumables of CS and LAS composition. So for example, if an electrode supplier wants to make a lot of Ni-alloy or SS bare electrodes, rods or consumables inserts (to be used with SAW, GMAW, SAW, OFW, and EGW processes) using multiple heats of controlled chemical composition, he would not be permitted to do it, since NB-2420(f) permits controlled chemical composition (as an alternative to a single heat) for only CS and LAS consumables. Likewise, if he wants to manufacture Ni-alloy or SS covered electrodes and wants to use multiple heats of controlled chemical composition as the core wire, he would not be permitted to do it because of the aforementioned proscription in NB-2420(f).
3. Although NB-2420(f) does not mention SMAW process, it can be reasonably inferred that the restriction on controlled chemical composition is applicable to the core wire of covered electrodes too, since the principle behind the restriction remains same.
4. Clause NB-2420(f) has nothing to do with flux. That is, the covering flux applied on covered electrodes is not subject to the restriction on controlled chemical composition. In other words, multiple wet mixes (rather than a single wet mix) can be used, as expressly permitted in the definition of lot class C3 electrodes, even for non-CS and non-LAS electrodes.

Conclusion on earlier editions: All editions of Section III NB dated 2015 and before, permit use of multiple wet mixes (in other words, controlled chemical composition is allowed) in the manufacture of not just CS & LAS electrodes, but also for non-CS and non-LAS electrodes such as ENiCrFe3, E309-15 electrodes, etc.

The 2017 edition of Section III NB saw an overhaul of NB-2420, through which the erstwhile definitions of welding consumable related entities (such as dry mix, wet mix, heat, etc.) were replaced with a reference to their equivalent definitions in SFA-5.01 of Section II Part C.

F. What Do the Other International Codes Say?

If only wet mix is allowed in the manufacture of one lot of non-CS and non-LAS electrodes, it would entail batch testing of every 600 kg of electrodes. Do other codes require this volume of testing?

F.1. KTA Code

The relevant German Nuclear Safety Standards for nuclear power plants, i.e. KTA 1408.1, 1408.2, 1408.3 which pertain to welding consumables require mechanical testing of every 5000 kg of electrodes. Refer Table 5-1 of KTA-1408.2, 2017 edition.

F.2. ISO Codes

Most ISO codes point to ISO-14344 in matters of electrode procurement and testing. The ISO-14344 contains mostly the same requirements as contained in SFA-5.01 of Section II Part C.

F.3. RCC-M Code

RCC-M code, Section IV, para S2430 requires that SMAW electrodes shall be of lot class C3 as defined in ISO-14344, shall be of same trade name, and shall have a core wire from one heat only. The requirement that the core wire shall be of one heat here – is regardless of the whether electrode is CS, LAS, non-CS, or non-LAS. It is also notable that no additional requirement regarding the covering flux needing to be from a single wet mix is specified.

G. Case for Revision in Code

A number of factors justify the case for revision in NB-2420 with regard to the above-discussed rule. A few of them are as follows.

G.1. Changes Done in 2017 Edition Only Intended Replacing the Definitions, Not The Intent

The 2017 edition of Section III NB witnessed an overhaul of NB-2420. This overhaul introduced ‘lot classes’ (such as C3 for covered electrodes, S2 for bare rods/ wires, etc.) of consumables under NB-2420 for the first time. Lot classes are defined under SFA-5.01 of Section II Part C. This perhaps eased the burden of including detailed requirements under NB-2420, and instead accomplish the objective by simply specifying the lot class for various categories of consumables.

The overall intent of these changes was to replace the existing lot definitions for welding consumables with SFA-5.01 definitions.  The erstwhile definitions (such as dry mix, wet mix, etc.) related to consumables were mostly equivalent to the corresponding definitions given in SFA-5.01 for these items and hence the changes made sense.

This indicates that NB-2420 did not witness any change in the intent regarding controlled chemical composition for non-CS and non-LAS consumables in 2017, and that the changes done were for the sake of convenience and uniformity between Section III NB and Section II Part C.

G.2. Code’s Restriction is Meant for Heat, Not Flux

Generally, a heat is defined as the material obtained from one furnace melt.

However, in cases where significant slag-metal reactions do not occur, an uninterrupted series of melts from the same set of source materials under same melting conditions can also be designated as a single heat, provided chemical composition of each melt stays within a controlled range. This amounts to controlled chemical composition, that is – use of multiple melts is permitted provided composition of all melts stays within a range established by the consumable supplier.

However, in cases where significant slag-metal reactions do occur (say, in melts involving reactive metals such as Al, Cu, Ni, Ti, Zi, etc.), such liberty cannot be permitted since one melt might be significantly different in composition from another, due to chemical reactions occurring during melting. For such cases, only the material obtained from one melt is allowed to designated as one heat.

This understanding, existing in Section II Part C since time immemorial, seems to be the reason behind the restriction imposed by NB-2420(f) (in editions older than 2017) regarding the use of controlled chemical composition for non-CS and non-LAS consumables.

Clearly, this restriction is intended only for metallic consumables (such as rods, wires, inserts to be used with OFW, GTAW, GMAW, SAW, EGW, etc.), and has no relation to fluxes of any kind. Therefore, the contentious rule introduced in 2017 edition, as described in para B above, & which continues to present day, and which has been attested to by Section III committee over multiple interpretations, is the result of NB-2420(f) not being transferred faithfully from the 2015 edition to the 2017 edition. The rule is therefore incorrectly understood.

G.3. Excessively and Unreasonably Stringent

The above discussion explains that if only wet mix is allowed in the manufacture of one lot of lot class C3 electrodes of non-CS & non-LAS type, the total quantity in one such lot gets restricted to 500 kg – 600 kg [this number may go up slightly for big consumable suppliers such as Lincoln electric, Bohler, etc., who may have large wet mix capacities]. Since each lot is required to be subjected to the requisite testing, the amount of testing that a fabricator who procures 30 tons needs to do – is extremely high.

Other equivalent international codes do not specify this kind of voluminous testing. ASME Section III NB, thus, is excessively and unreasonably stringent in this regard. A Code change is therefore, suggested.

G.4. Process of Manufacture of Non-CS & Non-LAS Electrodes is No Different From CS & LAS Electrodes

The process involved in the manufacture of covered electrodes, as described in para C.1, stays same for CS/LAS electrodes and Ni/Cu/Al etc. electrodes. Having multiple wet mixes, of controlled chemical composition, assures that the mechanical properties across the entire lot quantity made from multiple wet mixes would be uniform.

Treating electrodes made from different wet mixes as different lots adds no significant value to the electrode qualification exercise. 

H. Proposed Change in NB-2420

The last paragraph under NB-2420 is shown below. The proposed change in indicated in red:

‘In all cases, when filler metal of controlled chemical composition (as opposed to heat control) is used, each container of welding consumable shall be coded for identification and shall be traceable to the production period, the shift, the manufacturing line, and the analysis of the steel rod or strip. Carbon, manganese, silicon, and other intentionally added elements shall be identified to ensure that the material conforms to the SFA or user’s material specification. The use of controlled chemical composition, as an alternate to a single heat, is only permitted for carbon and low alloy steel consumables. Tests performed on welding material in the qualification of weld procedures will satisfy the testing requirements for the lot, heat, or combination of heat and batch of welding material used, provided the tests required by Article NB-4000 and this subarticle are made and the results conform to the requirements of this Article.’

This was all on this subject. Please do oblige with your thoughts, observations, etc. Thanks for reading the lengthy post.

The post Suggestion For Change Under NB-2420 of ASME Section III NB appeared first on mewelding.com.

In this article, I have listed a few suggestions for changes to NB-2400 of Section III NB. There is another article on this website titled ‘Suggestion for change under NB-2420’ which talks on a particular subject. That subject is too big to be included in this article; hence it has been made into a different article altogether.

The three proposals in this below article are a result of my observations in my own office work. There may of course be disagreements, rebuttals, etc. by knowledgeable people, but that is welcome. Strenuous discussion only makes the code evolve.

1. Replace ‘Heat’ With ‘Lot’ In Para 1 of NB-2420

The first para under NB-2420 mentions the word ‘heat’ several times. This word should be replaced by the word ‘lot’. The reason is described in the below paragraphs.

Background

The first paragraph of NB-2420 states:

‘The required tests shall be conducted for each lot of covered, flux-cored, or fabricated electrodes; for each heat of bare electrodes, rod, or wire for use with the OFW, GMAW, GTAW, PAW, and EGW (electrogas welding) processes (Section IX, QG-109); for each heat of consumable inserts; for each combination of heat of bare electrodes and lot of submerged arc flux; for each combination of lot of fabricated electrodes and lot of submerged arc flux; for each combination of heat of bare electrodes or lot of fabricated electrodes, and dry blend of supplementary powdered filler metal, and lot of submerged arc flux; or for each combination of heat of bare electrodes and lot of electroslag flux. The definitions in SFA-5.01 and the Lot Classes specified in (a) through (e) below shall apply.’

NB-2420(c), (d), (e) require bare electrodes/rods, consumable inserts, SAW wires, to be of lot class S2. The definition of lot class S2, given at SFA-5.01 of Section II Part C, permits use of controlled chemical composition as an alternative to one heat, in manufacture of lot class S2 consumables. This means that multiple heats, provided their chemical composition is controlled within a range, can be used in the manufacture of a lot, and the resultant quantity would still get counted as a single lot.

While the code intends that each lot of bare electrodes/rods/consumable inserts/SAW wires etc. be subjected to the requisite testing, the use of the word ‘heat’ at several places in the opening sentence of NB-2420 conveys the meaning that each heat used in the making of a lot is required to be tested. This is clearly not the intent of code.

The use of the word ‘heat’ here, in all editions from 2017 onwards, seems to be a continuation of use of the word from the 2015 edition – when all definitions were contained at NB-2420 itself, rather than references to lot classes of SFA-5.01. This use of the word ‘heat’ here, while appropriate in the 2015 and earlier editions, is in error, in all the later editions.

Proposal for change

The first paragraph of NB-2420 is reproduced below. The proposed changes are in red, and deletions are indicated as strike-outs.

‘The required tests shall be conducted for each lot of covered, flux-cored, or fabricated electrodes; for each heat lot of bare electrodes, rod, or wire for use with the OFW, GMAW, GTAW, PAW, and EGW (electrogas welding) processes (Section IX, QG-109); for each heat lot of consumable inserts; for each combination of heat lot of bare electrodes and lot of submerged arc flux; for each combination of lot of fabricated electrodes and lot of submerged arc flux; for each combination of heat lot of bare electrodes or lot of fabricated electrodes, and dry blend of supplementary powdered filler metal, and lot of submerged arc flux; or for each combination of heat lot of bare electrodes and lot of electroslag flux. The definitions in SFA-5.01 and the Lot Classes specified in (a) through (e) below shall apply.’

2. Remove ‘Listed P-Nos.’ From NB-2431(a)

The first para under NB-2431 provides exemptions to mechanical testing for batch qualification of welding material. The phrase ‘listed P-Nos.’ in NB-2431(a) causes some ambiguity. I explain below.

Background

NB-2431 states:

‘Tensile and impact tests shall be made, in accordance with this paragraph, of welding materials that are used to join P-Nos. 1, 3, 4, 5, 6, 7, 9, and 11 base materials in any combination, with the exceptions listed in (a) through (d) below:

(a) austenitic stainless steel and nonferrous welding material used to join the listed P-Numbers;’

The phrase ‘used to join the listed P-numbers’ at the end of above text conveys that the exemption from tensile and impact testing is applicable only for those austenitic SS & non-ferrous welding materials that are used to join P-nos. 1, 3, 4, 5, 7, 7, 9 & 11 base metals, and not for those that are used to join other base metals such as say, P-No. 8, etc.

However, interpretations III-1-77-249 and III-1-79-102 inform that the exemption for these welding materials remains applicable when they are used to join P-No. 8 too. In fact, III-1-77-249 indicates that the exemption remains good regardless of the base metals that are being welded.

In light of the above, one of the following two proposals may be adopted for revising the above clause. The proposed change is indicated in red.

Proposal 1

‘Tensile and impact tests shall be made, in accordance with this paragraph, of welding materials that are used to join P-Nos. 1, 3, 4, 5, 6, 7, 9, and 11 base materials in any combination, with the exceptions listed in (a) through (d) below:

(a) austenitic stainless steel and nonferrous welding material used to join the listed P-Numbers;’

Proposal 2

‘Tensile and impact tests shall be made, in accordance with this paragraph, of welding materials that are used to join P-Nos. 1, 3, 4, 5, 6, 7, 9, and 11 base materials in any combination, with the exceptions listed in (a) through (d) below:

(a) austenitic stainless steel and nonferrous welding material used to join the listed P-Numbers listed under QW-422 of Section IX;’

3. Batch Qualification Coupon Should Be Made with Highest Preheat

NB-2430 requires that the test coupon for batch qualification be made with the same preheat, interpass and PWHT that the production weld is going to see. This however causes some confusion as explained below.

Background:

NB-2431.1(c) states:

‘The welding of the test coupon shall be performed within the range of preheat and interpass temperatures that will be used in production welding. Coupons shall be tested in the as-welded condition, or they shall be tested in the applicable postweld heat-treated condition when the production welds are to be postweld heat treated’

The above paragraph desires that the test coupon prepared for batch qualification of welding material shall be prepared within the range of preheat & interpass temperatures that will be used in production welding.

An electrode (say E7018-1 SMAW electrode) is used in the following five kind of welds in production welding:

1. Weld 1: without preheat, without PWHT.
2. Weld 2: without preheat, with PWHT of 600°C.
3. Weld 3: with preheat of 150°C, without PWHT.
4. Weld 4: with preheat of 150°C, with PWHT of 600°C.
5. Weld 5: with preheat of 200°C, with PWHT of 600°C.

Does the code require five different test coupons for qualification of this electrode as per NB-2400? While NB-2400 provides no explicit answer to this question, two interpretations III-81-02 and III-1-77-64 provide a guidance that the test coupon must not be prepared with a preheat temperature lower than the preheat of production weld. In other words, if, for example, an electrode lot is going to be used in production welds – i) without preheat, ii) with preheat of 150°C, and, iii) with preheat of 220°C, then the code’s expectation is met if the test coupon is made with a preheat of 220°C.

In other words, in such cases when the electrode is going to be used with multiple preheat temperatures in production weld, it is enough to make just one coupon with the highest preheat among all of them.

This, however, runs counter to the metallurgical considerations and also the understanding established by QW-406.1 of Section IX.

Decrease in Preheat is Detrimental to Mechanical Properties

QW-406.1 stipulates that a decrease in preheat temperature requires requalification of welding procedure. In other words, if a procedure has been qualified with preheat – the production weld made with the help of this procedure must also be made with preheat only. If, however, a procedure has been qualified without preheat – the production weld may be made with preheat too, as doing so would constitute an increase in preheat – which is not prohibited by QW-406.1.

This indicates that decrease in preheat is detrimental to the mechanical properties of a weld. This thinking also conforms to the commonly understood behaviour of carbon steel and low alloy steels. An increase (within a reasonable range) in preheat, on the other hand, is considered beneficial.

Worst Condition Is Not Simulated

Welding qualifications (including batch qualifications of NB-2431) are generally sought to be done by simulating the worst conditions that the production job could potentially witness. [Toughness tests at sub-zero temperatures and long soaking hours in PWHT are examples of this]. If the qualification shows acceptable test results under these worst conditions, it can be inferred that the production welds made under easier conditions will surely possess acceptable mechanical properties.

Pursuant to this thinking, if a batch qualification is done without preheat – and shows acceptable results, it is akin to simulating the worst condition and still passing the test. Among the 5 production welds described on page 1, this qualification simulates weld 1, which is the worst condition among the five. Such a batch, when used in all five kinds of production welds described on page 1, can be expected to have acceptable mechanical properties.

Section III however, under such conditions as described above, stipulates that the batch qualification shall be done with the highest preheat temperature that the production weld might see. By doing this, the code ends up not simulating the worst condition that the job might see, but in fact ends up doing the opposite. Furthermore, there does not appear to be any basis for doing the batch qualification with the highest preheat temperature.

It is therefore proposed that NB-2431.1(c), first two sentences, be revised.

Proposal for change

The proposed revision is as follows (changes are shown in red):

‘The welding of the test coupon shall be performed within the range of preheat and interpass temperatures that will be used in production welding. When the welding material is going to be used with multiple preheat temperatures in production welds, the test coupon shall be prepared with the lowest preheat that will be applied to welding material when it is used in production. Coupons shall be tested in the as-welded condition, or they shall be tested in the applicable postweld heat-treated condition when the production welds are to be postweld heat treated.’

This is all I have to offer, currently. Please do share your thoughts in the comments section below.

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Changes in Article I: General Requirements

The following are the major changes that have been introduced in the 2023 edition, regarding general requirements contained in Article I.

Person Making Procedure Qualification Test Coupon Need Not Be an Employee

In 2021 edition, QG-106.1 specified that the persons producing procedure qualification test joints shall be either direct employees, or shall be personally hired by contract for welding by the qualifying organization.

Section IX, since the 2019 edition, has laid great emphasis on ‘supervision and control’. The persons making the procedure and performance qualifications must be under full supervision and control of the qualifying organization. The persons performing this role of supervision and control must be designated, and must be competent enough (documented proof must be available) to do this task.

Now, it is understood that for exercising supervision and control, it is not necessary that the person being supervised be an employee. Adequate supervision and control can be exercised over contract personnel too. Hence, this requirement that the person(s) producing procedure qualification test coupon be a direct employee – has been deleted.

Interestingly, this requirement of ‘direct employee’ was applicable to persons making procedure qualification test coupons, not those making performance qualification coupons. This was odd too. What is good for performance qualification must be good enough for procedure qualification too. So, this change makes sense.

Use of Qualifications to Earlier Editions of Code

Section IX has always allowed that WPSs, PQRs, and WPQRs qualified to earlier editions till as far back as 1962 edition can be used for any construction for which the current edition has been specified. Qualifications to editions prior to 1962 also can be used provided requirements of 1962 or any later edition have been met. However, new qualifications shall be done respecting the latest editions only.

The Section IX committee probably felt that involvement of 1962 edition made the matter unnecessarily complex, and didn’t add any significant value. Reference to 1962 edition therefore has been deleted. Qualifications to earlier editions can be used for construction to present edition. Period.

The idea is to prevent extensive redoing of welding qualifications.

Another thing – when a fresh WPS (for construction to the present edition) is written with the help of a PQR qualified to an earlier edition, it must be ensured that the essential (and when required supplementary) variables of the latest edition are satisfied in the PQR.

This was the intent of Section IX. However, this was not directly addressed in Section IX, and this intent was only visible through the interpretation IX-78-32.

The 2023 edition has corrected this anomaly. Second paragraph under QG-108 now states this matter unambiguously.

Changes in Article II: Welding Procedure Qualification

The following are the major changes that have been introduced in the 2023 edition, regarding
procedure qualifications contained in Article II.

Change of Transfer Mode Is Not An Essential Variable

Prior to 2021 edition, if a WPS was qualified with GMAW(S) mode and T < ½’’ (13 mm), the qualified T was limited to 1.1 times the coupon thickness. The lack of fusion problems faced when using GMAW(S) mode for low base metal thicknesses is a function of welder’s skill, and is not dependent on the welding procedure. This was realized, and the restriction of 1.1 times the coupon thickness was lifted, for procedure qualifications, while the same restriction continued to exist for WPQs.

In this edition, it was perhaps thought that change in transfer mode does not affect mechanical properties; GMAW(S) only requires a different skill than others. Hence, transfer mode has been made a non-essential variable now. In table QW-255, QW-409.1 (an essential variable earlier, for transfer mode) has been deleted, and QW-409.32 (a non-essential variable) has been introduced.

The WPS must specify the transfer mode that the welder must adopt.

Consequently, if a coupon is made partly with GMAW(S) and partly with GMAW(pulse) – the two depositions need not be considered separately as two different qualifications. They can be considered one.

This simplifies things, for those who use GMAW(S) in their WPSs.

Transfer mode continues to be an essential variable for performance qualification though.

Introduction of Optional Designator For Shielding Gas

This is a big ticket introduction of this edition. For bare solid CS & LAS fillers used with gas shielded processes (i.e. fillers of SFA-5.18 & SFA-5.28), Section II C – 2023 edition has introduced an optional designator for shielding gas.

This designator, which basically denotes oxygen equivalent of a shielding gas, appears at the end of the filler grade, for example – ER70S-6 OE H/L. ‘OE’ stands for oxygen equivalent, ‘H/L’ stand for the highest and lowest value of oxygen equivalent, and are indicated as numbers.

This means that the said filler will produce the same properties (as laid out in the classification tests of Section II C) when welded with any shielding gas having an oxygen equivalent within this range of ‘H’ and ‘L’. The oxygen equivalent is calculated by the following formula:

%OE = % of O 2 in shielding gas + (0.5 x %CO 2 in shielding gas)

To establish ‘H’ and ‘L’, the filler supplier must make multiple test assemblies, with a minimum of two – one with a shielding gas with OE of ‘H’, another with a shielding gas with OE of ‘L’. All test results must pass the acceptance norms for all classification tests specified in SFA specification.

The need for this designator arose because a filler gives different mechanical properties when used with different shielding gases. For example, the percentage of Mn & Si in weld metal, when the filler is used with a shielding gas of high OE, is lesser than those when the filler is used with a shielding gas of low OE.

Now, use of a OE 50/4 for example, indicates that the filler will meet all properties given under SFA when used with a shielding gas of OE 50, as well as when used with a shielding gas of OE 4, and also when used with a shielding gas of any OE between 50 and 4.

The OE of a shielding gas comprising of 100% CO2 would be 50 (as per above mentioned formula), while OE of a shielding gas comprising of 8% CO2 would be 4. The filler having a designator OE 50/4 will show all properties guaranteed under SFA for all shielding gas combinations having their OE in the range 4 and 50.

Section IX, recognizing this development in Section II C, has included oxygen equivalent as an essential variable under tables for GMAW and GTAW. No new qualification is required if the shielding gas used in production is within the range provided in the designation of electrode.

WPS Preparation Can Be Subcontracted

Section IX has always made it clear that the qualifying organization shall accept full responsibility of PQRs and WPQRs, and shall certify these records. Interpretation IX-18-47 made it clear that although the work of preparing PQR and WPQR can be subcontracted, the function of certifying these records cannot be subcontracted, and must be done by the qualifying organization themselves.

Read: Is it required to approve a WPS?

However, what about the WPSs? Can the work of preparing the WPS be done by a subcontractor, as long as the contractor assumes full responsibility for the production welding?

QW-200.1, till the 2021 edition said that: ‘Each organization shall prepare written WPSs that are…’. Likewise, QW-200.2 began by saying that: ‘Each organization shall be required to prepare a PQR which is…’. This made people think that the Section IX mandates the qualifying organization to perform the clerical work of preparing the WPS, in addition to qualifying it.

However, that is not the intent of Section IX. The above mentioned lines from QW-200.1 and QW-200.2, which gave off the meaning that the organization must prepare the WPS, have been deleted.

In effect, you can have your WPS prepared by an outside agency, as long as the PQR referred on it was qualified by you, and you assume full responsibility for the production welding.

Change Under QW-202.4

When dissimilar thickness joints are welded, QW-202.4(b)(1) allows the thicker member to be of unlimited thickness if the PQR is done on a coupon of ¼ inch (6 mm) or more, for fancy metals such as nickel alloys, titanium alloys, and zirconium alloys, and if the joint is made between similar metals.

For all other metals, this threshold is 1 ½ inch (38 mm); meaning that if the PQR was done on a coupon of thickness 1 ½ inch (38 mm) or more, the thicker side of the production weld can be of unlimited thickness.

Between QW-202.4(b)(1) and QW-202.4(b)(2), another difference besides the thickness threshold is the use of the term ‘similar’. This use of this term under QW-202.4(b)(1) earlier, indicated that the liberty granted by this clause was good only if the joint was made between ‘similar’ metals. This loosely meant that the metals need to be of same P-number, to avail the liberty given in this para. The reply given by Section IX to interpretation IX-17-67 affirmed this thinking.

The committee probably did a rethink on the matter. The word ‘similar’ has been removed.

This means that the liberty granted by QW-202.4(b)(1) is good not just when a joint is made with different P-numbers within the bunch indicated in this clause (for e.g a P-No. 45 + P-No. 43 joint), but also when only one of the sides of the joint consists of a metal having one of those P-numbers (for e.g a P-No. 1 + P-No. 43 joint).

Weave Width To Be Considered In Calculating Heat Input

QW-409.1 tells how to calculate heat input per unit length during welding process. This (V x I x 60 /speed) formula does not take into account the weaving action that many welders deploy during welding. The thinking goes that if a welder does weaving, the resultant speed would be slow, which would reflect in a higher heat input.

Slow travel speed can be in the form of sheer slow speed, or may result from weaving action. In weaving action, the heat is distributed across an area, and is not concentrated over per unit length, and therefore may not result in harming the weld due to high heat input. In other words, the weaving action should be taken into account when calculating heat input.

The 2023 edition takes care of this, albeit only for cladding, at QW-409.26. The strip width in the erstwhile formula has been replaced by bead width. So, the weave width is accounted for. Though, it must be said that the formula should not be called as heat input per unit length; in fact, it is better to call it as heat input per unit area.

The argument remains same for non-cladding welds too. The weave width ought to be part of the heat input calculation formula at QW-409.1. This will probably appear in the 2025 edition of Section IX.

Changes in Article III: Welding Performance Qualification

The following are the major changes that have been introduced in the 2023 edition, regarding performance qualifications contained in Article III.

Welder May Weld With Any Other WPS

Section IX has always intended that a welder (/welding operator) is not limited to the WPS that he used while doing his performance qualification test coupon welding. In fact, he can use any other WPS for production welding, provided he stays within the qualified limits of the essential variables for that process.

This has been clearly spelt at the last paragraph of QW-304 and QW-305 for welders and welding operators, respectively, and also reiterated in interpretation IX-17-44. It was probably felt that this should be said upfront and loudly.

Hence, this matter has been included at the outset, under QW-300.1, and deleted from QW-304 and QW-305.

Engagement In Machine Welding/Automatic Welding Extends Validity For Both

The 2021 edition indicated that the continuity of welding operators doing machine welding and automatic welding be tracked separately, for the purpose of extending the validity of their performance qualifications. That is, engagement in machine welding will not extend validity for automatic welding, and vice versa.

The 2023 edition says that while engagement in machine welding extends validity of both machine and automatic welding, engagement in automatic welding extends validity for automatic welding only.

Multiple Performance Qualifications Are Not Allowed In A Fillet Weld Coupon

Section IX allows us to carry out multiple performance qualifications in a single coupon – be it several welders using the same or a different process, or an individual welder using different processes. This has been laid out under QW-306.

The 2023 edition makes it clear that such multiple qualifications are permitted only for groove weld coupons, and not on fillet weld coupons. This makes sense, because one of the tests for a fillet weld coupon is macro examination, in which complete root fusion is checked. If multiple welders are making a fillet weld, the root fusion skill can be checked only for the first welder.

Use of Optional Designator ‘A’ in ER70S-6 Filler

The 2023 edition of Section II Part C, at SFA 5.18, has introduced use of the optional designator ‘A’ at the end of ER70S-6 fillers. The use of this designator indicates that the filler has restricted manganese and silicon content (Mn < 1.6% and Si < 1%). This allows the weld metal deposited with this filler to be designated as A-number 1 of Section IX (which would otherwise not be possible).

Ordinarily, the specified upper limits of Mn & Si for ER70S-6 filler are 1.85% and 1.15% respectively. This means that the composition cannot be classified under any of the A-numbers under QW-442. Now ER70S-6 is a very commonly used filler, and not being able to assign an A-number to it is not cool, or so the committee felt. Hence, the optional designator has been introduced, which will limit Mn & Si to the limits permitted for A-number 1.

Thus, ER70S-6A filler would meet all requirements of ER70S-6, but vice-versa may not be true.

The practical outcome of this is that ER70S-6A can be specified in a WPS using the support of a PQR qualified with ER70S-2 or ER70S-3, or any other filler which produces weld metal having A-number 1.

It should be noted that this change (use of optional designator ‘A’) has not occurred in Section IX, but has in fact appeared in Section II C. It is included in this article here because it affects directly the code users using Section IX.

Other Changes

Following are other miscellaneous changes that have occurred in 2023 edition, besides the above described changes.

Additive Manufacturing

The exercise of building components through sheer weld metal build up, without use of base metals, in simple terms – is what is called additive manufacturing. A whole new article, Article VI, titled ‘Material Manufacturing Using Wire Additive Welding’ has appeared in Section IX.

It contains rules for qualifying WPSs for additive manufacturing. The table QW-651 contains essential and non-essential variables when additive manufacturing is accomplished with GMAW process. These variables are similar to the variables for ordinary GMAW process, except that multiple coupons are needed – one welded with highest heat i/p & highest inter pass temperature and another welded with lowest heat i/p and lowest inter pass temperature.

The production welding can then be done within this range of qualified heat i/p and inter pass temperature.

What is not very clear is – why could these rules not have been added as a conjunct to QW-255 – the table for ordinary GMAW. Similar to how subsidiary tables are added for corrosion resistant and hard facing overlays along with tables for main welding processes, a table could have been added as QW-255.2 to describe additive manufacturing with GMAW.

Since, parts are mostly made up of weld metal only, it is therefore also necessary to have P-numbers for weld metal, as opposed to having them for base metals. Consequently, under QW-422 (the big table containing P-numbers), a couple of pages have been introduced detailing P-numbers for weld metal produced using commonly used fillers with GMAW, such as ER70S-2 etc. Basically, all fillers under SFA-5.9, SFA-5.18, and SFA5.28 have been assigned a P-number.

What I would like to see in the next edition is P-numbers for fillers classified under other SFA specifications too.

This is needed because – when you do repair in an already welded joint welded with a different process (for e.g. you want to repair with SMAW in a SAW welded joint), it is difficult to judge the applicability of a PQR for that repair. Because, essentially you are welding within a weld metal, not on the base metal.

Unless you can assign a P-number to the weld metal, how then can you judge whether the PQR in your hand is good enough or not.

Impact Testing of Heat Affected Zone

Earlier editions of Section IX allowed that when a PQR has been previously qualified to satisfy all requirements including impact tests, but one or more supplementary essential variables has changed, then it is only necessary to make a new coupon using same procedure but with the changed supplementary essential variables, with the coupon long enough to take out the necessary impact specimens. This remains unchanged in 2023 edition too.

The earlier editions also allowed that when the previously qualified procedure has satisfactory weld metal impact tests, then it is only necessary to do HAZ impact tests, when such are required by the construction code. This provision has been discontinued in the 2023 edition.

The committee probably felt that the when/how many/what temperature/orientation of
specimen/acceptance criteria regarding impact testing is best left to the construction code.

This was all. Thanks for reading. There is a comments section below if you would like to say something.

The post Notes On Major Changes In ASME Section IX: 2023 Edition appeared first on mewelding.com.

‘Background: Company A qualified a WPS to join an unlisted base metal (similar to P-Number 5A Group 1) to itself in accordance with QW-283 by buttering both groove faces using a filler metal that does not conform to an AWS classification, but is identified on the WPS and PQR by trade name. The buttered ends were postweld heat treated and machined so that the buttered thickness after machining was not less than 3/16 inch. The minimum buttering thickness in all cases listed will be greater than 3/I6 inch. The buttered ends were then welded together using a different filler metal and postweld heat treatment was not performed on the completed groove weld. The required mechanical tests were performed in accordance with QW-202.2(a). Notch toughness testing and hardness limits are required by the applicable Code for the heat affected zone and deposited weld metal. The maximum heat input qualified by Company A for buttering the groove faces was 25,000 J/in. and for welding the groove weld was 65,000 J/in.

Company B qualified a WPS to butter and heat treat the weld ends (but not perform the groove weld assembling the buttered parts) by making a groove weld in the same unlisted base metal using the same process, filler metal, and heat treatment temperature range that was used for buttering by Company A. The maximum heat input qualified by Company B for buttering is less than the maximum heat input qualified by Company A for the buttering and the groove weld.

Company C qualified a WPS to butter and heat treat the weld ends (but not perform the groove weld assembling the buttered parts) by making a groove weld in the same unlisted base metal using the same process, filler metal, and heat treatment temperature range that was used for buttering by Company A. The maximum heat input qualified by Company C for buttering is greater than the maximum heat input qualified by Company A for the buttering, but less than the maximum heat input qualified by Company A for the groove weld.

Question: Is Company A’s WPS qualified to perform the groove weld for buttered parts produced by Companies B and C for any heat input up to the maximum heat input of Company A’s WPS?’

Discussion 

Here is a pictorial representation of the qualifications done by company A, B, & C.

The qualifications done by company B & C will look like the following. 

And here is the qualification by company C.

We know that QW-283.2 allows that buttering can be qualified by a simple groove weld if the composition of the buttering and the subsequent groove weld is same. Companies B & C made use of this provision to qualify their WPS. 

QW-283.4 gives guidance for situation when the groove weld after the buttering is done by a different organization. Per QW-283.4, the buttering can be replaced in test coupon by a P-no. base metal having a nominally similar chemical composition to the buttering on production. This provision is, of course, not required here because company A qualified its’ PQR with buttering. 

Knowing about QW-283.2 and QW-283.4 however is not enough to answer the question asked in the interpretation. The buttering on the job is done by company B & C. The company A only needs to make the groove weld. Impact toughness is required for this application. Given these conditions, this gives rise to some interesting questions. 

Generally, does the buttering deposited by company B & C need to satisfy the essential variables of company A’s WPS? 

Does it have to be made with the same trade name of filler metal as used by company A for buttering? 

Does it have to be made with a heat input lower than that qualified by company A for buttering?

Does the heat treatment done by companies B & C need to be essentially same as that qualified by company A for buttering? 

The answer to these questions is as follows. 

The buttering was deposited by companies B & C. At the time of buttering, all variables of Section IX should have been satisfied. That is, the variables adopted during buttering should have been in consonance with the procedure qualification done by them. 

Specifically, the filler used for buttering should be of same trade name as that used in test coupon. The PWHT given to buttering should be essentially same as that done in test coupon. The heat input in any pass during buttering should be less that qualified during test coupon welding. All these things have nothing to do with what was done at company A. 

Now, when the job arrives at company A, all that the company A has to do is to make sure that the groove weld to be done by it satisfies the variables qualified in the PQR done at its’ works. In this exercise, only the chemical composition of the buttering is a factor. It is not necessary for the company A to simulate fully the conditions (filler trade name, PWHT, and heat input) adopted by company B & C in depositing the buttering. Because the QW-283.4 is clear in communicating that it is enough to choose a P-no. base metal (for test coupon) having a nominally similar chemical composition to the buttering. 

The answer to the question asked in the interpretation is therefore, yes. 

The background given in the question above focusses only on the matter of heat input, and not so much on the filler metal trade name and PWHT. However, the reasoning outlined above applies to all variables. 

Thanks for reading. 

The post Practice Case 16 – WPS For Welds With Buttering appeared first on mewelding.com.

“Background: Company A qualified a WPS joining a P-Number 5A material to itself in accordance with QW-283 by buttering both groove faces using a filler metal that does not conform to an AWS classification but is identified on the PQR by trade name. The buttered ends were postweld heat treated and machined so that the buttered thickness after machining was not less than 3/16 inch. The buttered ends were then welded together using a different filler metal. The required mechanical tests were performed. Company B qualified a WPS to butter and heat treat the weld ends (but not perform the groove weld assembling the buttered parts) by making a groove weld in P-number 5A material using the same process, filler metal, and heat treatment temperature range that was used for buttering by Company A. The required mechanical tests were performed. 

Question (1): Is it required that the production buttering be made with the same heat of the filler metal that was used for the buttered portion of the procedure qualification test coupon? 

Question (2): Is the company B WPS qualified to butter and heat treat the weld ends of the production parts? 

Question (3): May a third company (Company C) use test coupons that have been buttered, heat treated, and machined by Company A (following a qualified buttering WPS) to qualify a WPS for only making the groove weld joining the buttered parts?”

For reference, here is what the qualifications done by company A and B look like, in all likelihood.

And, the qualification done by company B will look like the below figure.

Let us see question (1) first.

Is Same Heat Of Filler Needed?

No, the production weld is not required to be made with the same heat of filler as the test coupon. At least, Section IX does not require this. This holds good regardless of whether the weld is a groove weld or buttering or corrosion resistant overlay or whatever.

When a non-ASME grade filler is used for making the test coupon, Section IX requires that the production weld be made with the same grade of filler (though the same trade name is not needed). The WPS must identify the trade name of the consumable (QW-404.33); and – if it is desired to change the trade name, it will only require an amendment of the WPS and not its’ requalification.

However, when impact is a requirement, and a non-ASME grade filler is used for making the test coupon, QW-404.12 specifies that a change of trade name also requires requalification of WPS. 

However, no clause in Section IX requires using same heat or lot number of the filler in production weld which was used in making the test coupon, no matter what. The answer to the question (1) is therefore ‘No’. 

Let us see question (2) now. 

Can A Groove Weld Qualification Support Buttering?

The qualification done by company B is a groove weld. Using this qualification, they would like to carry out buttering on the weld ends of P-No. 5A metal, and heat treat them. Does Section IX permit this? In other words, does a groove weld qualification support buttering welds?

Yes, it does. 

QW-283.2 para 2 permits that when the buttering and the subsequent groove weld are going to be made with the filler metal of same composition, then the qualification for such welds can be done by joining the first member to the second directly, through a groove weld. Which is what company B has done. 

Even if one does not take the support of QW-283.2, the buttering is akin to a build-up. A build-up can anyway be supported by a groove weld qualification, by virtue of QW-202.3. So, the answer to question (2) is yes. 

When assessing applicability of groove weld qualifications to build-ups, one should treat build-up as a groove weld, and verify each essential variable for applicability. 

Let us examine question (3) now. 

Does The Test Coupon Base Metal Need To Be Of Same PWHT Condition As The Job?

Question (3) touches upon a number of aspects related to welding qualifications. 

First, if the job is a buttered item, does the test coupon also need to be buttered? Is the answer any different if the buttering thickness is less than 3/16 inch (5 mm)? 

Second, does it matter that the base metal used for procedure qualification test coupon be of same PWHT condition as the job? 

Third, is it required that the base metal used for test coupon be procured by the qualifying organization themselves? Can the qualifying organization borrow/acquire base metal from another organization who may have done some welding on the plate? 

Let us see all three aspects one by one. 

It is understood from the background and questions (1) to (3) that the WPS that the company C is trying to qualify is for a job that comprises of two P-No. 5A parts that have been buttered and heat treated by some other company, and need to be now joined together by a groove weld by company C. 

The test coupon parts that company C receives from company A are buttered and heat treated. That is how the job is going to be, as well. However, is it necessary that the test coupon be buttered and heat treated too? 

No. It is not quite necessary. If the buttering thickness on the production weld exceeds 3/16 inch (5 mm), then QW-283.4(b) permits that the groove weld can be qualified by substituting the buttered base metal with any P-number metal that nominally matches the chemical composition of the buttering. In other words, buttering need not be simulated on the test coupon. 

However, if the buttering thickness on the production weld is less than 3/16 inch (5 mm), then Section IX assumes that the buttering surface has significant dilution from the base metal. In this case, the qualification should simulate the job condition. That is, the test coupon for groove weld should be made by buttering (thickness of which should be equal to the buttering on the production weld) on the base metal and then joining it to the second part. 

Secondly, it is not intended by Section IX that the base metal for test coupon should be of same PWHT condition as the production base metal. This understanding appears in the interpretation IX-89-84.

In the above case, although company C uses heat treated base metals for making the test coupon, it is not necessary that it be this way. If they used non-heat treated base metals, that would be perfectly fine too. 

Thirdly, can the company C use base metal (for making the test coupon) that has been buttered and heat treated by company A? 

Yes, it can. Section IX places no requirements on where the test coupon base metal has been sourced from, as long it is of desired P-number. 

The answer given by ASME to question (3) reads as: “Yes, provided the thickness of buttering after machining is not less than 3/16 inch.”

This is all, regarding this matter. Please share your thoughts in the comments section below. 

The post Practice Case 15 – Welds With Buttering appeared first on mewelding.com.

In this article we shall see various purposes of buttering, how to qualify a welding procedure for such welds, and some interesting situations around the same.  

Purposes Of Buttering

Buttering can have different objectives, based on the application, and the particular circumstance in question. Some of the possible objectives of buttering are as follows: 

1. When Dissimilar Base Metals Are Joined 

As an example, consider that two base metals – one is SA 240 typ 316, another is SA 515 Gr 70, need to be joined. These two are dissimilar metals, that cannot be joined by the common SS electrodes. In such cases, the carbon steel part is buttered with a stainless steel filler such as E309-15, which is known for high nickel and high chromium content than the usual 18Cr-8Ni variety. 

Once the E309-15 buttering is deposited on the carbon steel metal, the surface becomes compatible for welding with the stainless steel part. The buttering here thus serves the purpose of providing a suitable transition weld for subsequent completion of joint. 

2. Lamellar Tearing 

Suppose that a T-joint groove weld needs to be made between two thick carbon steel members. Due to high thickness, the volume of weld metal to be deposited is high. We know that when a large volume of molten metal is deposited in a groove, the amount of residual stress is also proportionately high. High stress exerts a pull on both the base metals. 

In any metal that is fabricated by rolling process, there can be expected a presence of lamellar defects/discontinuities that orient themselves along the direction of rolling. 

When high residual stresses of a joint exert on a base metal having such defects, the discontinuities present near the weld fusion line tend to get opened up and become enlarged. This is called lamellar tearing. That is obviously undesirable. 

So, before making the groove weld, a buttering is deposited on the rolled base metal. Since the volume of buttering weld metal is less, the amount of residual stress is far lower, and lamellar tearing is avoided.

When a subsequent groove weld is made between the buttered surface and the second part, the residual stress generated by the groove weld will exert its pull in the buttering weld metal (and not the rolled base metal underneath).

Since the buttering is akin to a casting (since it is a weld metal), it is not expected to have lamellar defects. Hence, the problem of lamellar tearing in thick groove welds is prevented by using the buttering, in this manner. 

3. Different Essential Variables After Buttering 

Sometimes, the welding of an attachment falls at such a stage of fabrication at which no PWHT is possible. 

Suppose that the attachment is made up of P-No. 1 metal, and the base part is made up of P-No. 3 metal. The fabrication exigencies dictate that no heat treatment is possible at the stage when the weld joint between this attachment and base part is made. But metallurgical considerations require that welding on P-No. 3 metal must see PWHT. These opposing considerations thus create an impasse. 

In such situation, carbon steel buttering is done on the P-No. 3 part in an upstream stage, when PWHT is possible. A PWHT is done after the buttering; this satisfies the PWHT requirement of P-No. 3 metal. Later on, when the stage of attachment welding arrives, the weld needs to be made between P-No. 1 attachment and carbon steel buttering. This weld does not require PWHT, from metallurgical point of view. 

Thus the problem of PWHT is circumvented, by buttering with carbon steel weld metal. 

There may be several other objectives, one or more of which may be applicable to a job. Above three are the ones to which I have had some exposure. 

How To Qualify PQR For Welds With Buttering

This subject is addressed at QW-283 of Section IX. Basically, it says that the sequence of steps in job must be simulated in test coupon as well. If the job is going to have buttering followed by heat treatment, and then the joint with second part, then the test coupon must be made in the same fashion too. 

All essential variables applicable for that process under QW-250 are applicable here too, except that QW-409.1 (increase in heat input is not allowed for any pass) is to be considered as an essential variable if the buttering thickness in the test coupon is less than 3/16 inch (5 mm). 

An important variable to keep in mind in such qualifications is the buttering thickness. It has been told as a non-essential variable, if it is more than 3/16 inch (5 mm). That is, the buttering thickness that must remain on the production member after all machining is completed – must be specified by the WPS. 

If the buttering thickness in the test coupon is less than 3/16 inch (5 mm), then the actual deposited thickness on the test coupon (before the second part is welded) must be recorded. This thickness then becomes the minimum qualified thickness for all production welds that are to be supported with this procedure. 

Exemptions 

QW-283.2 lists a key interesting exemption to the qualification requirement described in the above paragraphs. This exemption says that if the buttering and the subsequent weld are to be made with the same filler, then the qualification can be done by welding the first member directly to the second member. That is, one need not undertake the hassle of depositing the buttering first, and then a groove joint. 

Of course, this goes without saying that this is allowed only when all essential variables for buttering and the subsequent weld are same. 

For example, if there is a PWHT for buttering, and no-PWHT for the subsequent weld, then the essential variables are clearly different. This exemption does not apply to such cases. For such cases, the coupon has to made by depositing buttering first, followed by PWHT, followed by butt weld with the second part. 

Interpretation IX-16-45 presents a very pertinent example of this. 

Qualifying The Second Weld Separately

When the second part of the weld (the one that joins the second part to the buttered part) is to be made using a different set of essential variables (for e.g. filler may be different, PWHT condition may be different, etc.), or is to be made by a different organization – then it is required to qualify the buttering separately, and the second weld separately. 

QW-283.4 defines rules for procedure qualification when the second portion of the weld has to be qualified separately. 

If the buttering thickness is less than 3/16 inch (5 mm), then the job must be simulated ditto. That is, buttering must be done first, followed by the second weld. All essential variables of QW-250 are applicable, except that QW-409.1 is also applicable. 

If the buttering thickness is more than 3/16 inch (5 mm), then the qualification for the second portion of the weld can be done by choosing a base metal that nominally matches the chemical composition of the buttering and weld it to a base metal of same P-number as the second part. In other words, the hassle of buttering need not be repeated in the test coupon. [This relaxation is not available when the buttering thickness is less than 3/16 inch (5 mm) (further reaffirmed by Interpretation 15-1302)].

However, Reverse Is Not Allowed 

We have seen above that when the production base metal is a buttered part, and needs to be welded to a second part, the test coupon for such weld need not be a buttered item – and it is enough to take a base metal that has nominally the same chemical composition as the buttering (provided buttering thickness is > 3/16 inch (5 mm) on the production part). This is all nice and good. 

However, if the test coupon is a buttered item, it cannot be used to support a production weld that is not a buttered item, but is in fact a P-number base metal of similar chemical composition. This finds affirmation in an interpretation as well, IX-86-18. 

In essence, while a simple groove weld PQR can support a job that has buttering, a PQR having buttering cannot support a simple groove weld not having any buttering.

This was all I had to offer on this subject. Thanks for reading. Leave a comment below if you would like to say something.

The post Procedure Qualification For Welds With Buttering appeared first on mewelding.com.

The article begins with explaining the meaning of P-Number, various important aspects worth knowing about P-numbers in ASME Section IX, and how to use P-Number in procedure qualifications and welder qualifications in accordance with Section IX.

What Is P-Number?

P-Numbers are alphanumeric designations that are assigned to base metals with the purpose of reducing the number of welding procedure qualifications required.

In simple terms, ideally, the base metal chosen for procedure qualification should be same as the one used in production welding. However, if we were to do a procedure qualification for every base metal used in production, the number of procedure qualifications would be ridiculously large – which would be quite uneconomical, time-consuming, and unnecessary.

Therefore, in order to reduce the number of PQRs, ASME has grouped base metals that have similar weldability characteristics into same P-Numbers. Base metal having same P-Number can be substituted in PQR for the base metal in production. This thus reduces the number of PQRs that need to be qualified.

This assignment of P-Numbers is done based on the “comparable base metal characteristics, such as composition, weldability, brazeability, and mechanical properties, where this can logically be done.”

However, “These assignments do not imply that base metals may be indiscriminately substituted for a base metal that was used in the qualification test without consideration of compatibility from the standpoint of metallurgical properties, postweld heat treatment, design, mechanical properties, and service requirements.” This is as per QW 420.

The welding engineer should take into consideration all these factors when deciding the applicability of a PQR for a WPS.

Important Aspects Of P-Number As Per Section IX

• The term alphanumeric designation in the description given in QW 420 indicates that each P-No. designation shall be considered as a separate P-No. For example, base metals assigned P-No. 5A are considered of separate P-No. from those assigned P-No. 5B or 5C.

• An important thing to note here is that P-Numbers are not solely determined by the material specification. The grade/type greatly influences the P-No. assignment of a metal. In ASME Section II Part A structure, the material specification mainly points us to the product form, while the grade/type pins down the chemical composition. The chemical composition and product form are both taken into account to determine the P-No. of a metal.

• The P-Numbers assigned by ASME are listed in Table QW 422 in ASME Section IX for various base metals. The base metals contained in this table are mostly those that are specified in American standards. In recent years however, non-ASME base metals have also been added to this table, such as 16Mo3, IS2062 etc.

• “If an unlisted base metal has the same UNS number designation as a base metal listed in Table QW/QB-422, that base metal is also assigned that P-Number or P-Number plus Group Number.”

• “Material produced under an ASTM specification shall have the same P-Number or P-Number plus Group Number and minimum specified tensile strength value as that of the corresponding ASME specification.”

• Base metals that are not listed in the table QW 422 are termed as ‘unassigned metals’ in Section IX parlance. A procedure qualified using an unassigned metal is only good enough to support welding of that unassigned metal.

Broadly speaking, P-Numbers can be categorized into following groups for various alloy systems (this information is reproduced from QW 420):

Group Number

Besides P-Numbers, Group Numbers have been assigned to ferrous base metals. These are subsets of P-Numbers, and are applicable when toughness requirements are a consideration.

I have written another detailed article on this website covering the subject of Group-Number – a supplementary essential variable. The article can be found here.

This one here is another interesting article in this context.

Note that P-Number is an essential variable, whereas Group Number is a supplementary essential variable.

P-Number For Procedure Qualification

Change in P-Number is an essential variable for almost all welding processes under QW 250, which means that change in P-Number is not permitted. This has been addressed in QW 403.11 (for most of the processes under QW 250). For corrosion resistant overlays and hard facing processes, this has been addressed in QW 403.20.

QW 403.11 says that, “Base metals specified in the WPS shall be qualified by a procedure qualification test that was made using base metals in accordance with QW-424.”

QW 424 further enunciates the rule clearly. A table given under QW 424 lists on the left hand side various combinations of base metals used for procedure qualification coupon. On the right hand side are listed the qualified base metals for those combinations.

The table is pretty straight forward, and easy to comprehend. From this table, we understand that a procedure qualified with P-No. 5A, 4, 3 or 1 welded to itself (most of the carbon steel and low alloy steels used for commercial applications get covered within these P-Numbers) can be used to support WPS for welding that P-No. base metal welded to each of the lower P-No. base metals.

This matter finds mention in a couple of Interpretations as well (IX-82-29, IX-81-15, IX-83-56) which confirm this inference.

The table in QW 424 is reproduced below for reference. This reflects the content in the latest edition of Section IX, that is – 2021 edition.

1-to-1 Rule For Unassigned Metals

The above table tells us that a qualification on a grade of an unassigned metal qualifies the procedure for that unassigned grade of base metal only. Conversely, if the base metal in production joint is an unassigned base metal, the procedure must be qualified using that grade of unassigned metal only. In other words, when unassigned metals are involved, the procedure qualification exercise should be 1-to-1, vis-à-vis the base metals.

It is worth noting that a PQR, when qualified on a base metal meeting a non-ASME national or
international standard, cannot be used to support welding of an ASME grade metal, even if the ASME grade metal is essentially equivalent to the PQR base metal (since it is understood as an unassigned metal). The interpretation IX-95-21 presents an example of this.

This may seem a little harsh; but perhaps such things have to be resorted to when writing rules that need to be consistent over a scale as large as that of Section IX.

P-Numbers for Welder Qualification

P-Number is an essential variable for welder qualification too, as per ASME Section IX. However the rules for applying this variable for welder qualifications aren’t as stringent as for procedure qualification. I have written another article, wherein I have addressed this subject in some detail. The article can be accessed here.

So this was all about P-Numbers as per ASME Section IX. Please do leave your thoughts in the comments section below.

See More:

A-Number On A WPS

The post P-Number As Per ASME Section IX appeared first on mewelding.com.

A WPQR is a record of actual events that occurred during a welder’s performance qualification in accordance with ASME Section IX. Below is the suggested format given at the Non-mandatory Appendix B of Section IX.

Note that this format is only a suggested one. The fabricator is free to choose any other format as long as it addresses all essential variables, types of tests done, test results, and the ranges qualified in accordance with QW-452. These contents are mandatorily required. As long as these are addressed, any format is fine. This has been specified in QW-301.4.

When this format is used, there can be several equally acceptable ways of addressing each field. Herein this article, I have shared my take on how these fields can be filled. These observations are borne out of personal experience.

The Range Qualified Can Be More Restrictive Than Section IX

The ‘Actual Values’ column on the form is strictly a reportage of actual variables adopted in the preparation of the performance qualification coupon. The values under ‘Range Qualified’ column are derived by applying the rules given in Article III – Welding Performance Qualifications.

A notable feature about Section IX, and this finds mention several times on this blog, is that Section IX only specifies minimum requirements expected from a welding qualification (procedure or performance). Based on the application, the welding engineer may specify more restrictive requirements than Section IX.

That would be completely acceptable.

Therefore, the values to be mentioned under range qualified can be more restrictive than what the Section IX permits.

Only Qualified Thickness & Diameter Need to be Addressed Under ‘Range Qualified’ Column

A peculiar inexplicable thing about Section IX is the stipulation in QW-301.4 that requires only the ranges qualified in accordance with QW-452 to be recorded under the ‘range qualified’ column of QW-484A. Now, QW-452 only talks about thickness and diameter.

So, is it required to mention qualified ranges of only thickness and diameter?

This seems odd, considering that spaces have been provided on the format for other variables too, such as backing, F-Number, etc. Also, other variables are also important too. For example, a welder qualified with backing can weld only with backing.

He can’t weld on production welds not having a backing. Why should this not be indicated on the WPQ format under ‘range qualified’ column?

The understanding given in QW-301.4 has been further reinforced in QG-104, which in the 2021 edition, gives a clear indication that the ranges qualified required by QW-301.4 only have to be recorded in the QW-484A format. An interpretation, IX-89-30, which addresses precisely this matter, further establishes this understanding firmly.

So, this tells us clearly that the authors have intended that only thickness and diameter are to be recorded in the range qualified column. Why would the authors intend this way?

The answer to this is that the intent behind this is not known. However, it is a good idea to include ‘range qualified’ for all variables, regardless of what QW-301.4 says.

Let’s now see one by one the one way to complete this form.

1 – Welder’s Personal Details

These details may include the welder’s name and/or staff number. The idea is to uniquely identify the welder.

2 – Identification Number

This is the qualification number/ stamp/ symbol that identifies the performance qualification done by the welder. A welder may have several qualifications to his name. Using each of these qualifications, the welder may have gained eligibility to weld with different variables.

Each qualification has to be uniquely identified. This identification number is the way to identify different qualifications. It has nothing to do with the identity of the welder.

For example, an organization has three different kinds of qualifications (that are needed to cater to its production requirements). One qualification is with SMAW process in 1G position. Second qualification is with SMAW process in 5G position. Third qualification is with GTAW process in 2G position.

The organization identifies the welders qualified with first type of qualifications with a stamp ‘A’. The welders qualified in second qualification are identified with stamp ‘B’, and those qualified in third type of qualification are identified with stamp ‘C’.

3 – Identification of WPS

In this space, the WPS used for the preparation of the performance qualification test coupon should be mentioned along with its’ revision number and/or date. The idea is to uniquely identify the WPS.

Note that a qualified WPS is compulsorily required for making a welder performance coupon. In other words, the WPS must be supported by an appropriate PQR. A Standard WPS (or SWPS) is also acceptable.

Another notable aspect here is that if the WPS specifies preheat or PWHT, these can be ignored while preparing the WPQ coupon. In other words, preheat and PWHT are not required for a WPQ coupon, even if the WPS that is being used to prepare the coupon specifies it.

These requirements have been specified under QW-301.2.

Note: Although Section IX gives this liberty of ignoring preheat and PWHT, the welding engineer may still opt to include these keeping the application requirements in mind. For example, all production welding in my shop is done with preheat. I am of view that it takes some skill on welder’s part to weld with a high preheat of 300°F (150°C).

Therefore, all WPQ coupons in my shop are made with preheat. That is, I make the welder weld his coupon with preheat, and prove his ability.

Remember, Section IX only sets forth minimum requirements expected from welding qualifications. It is for the welding engineer to define the contours of these qualifications such that the needs of application are satisfied in the best manner possible.

Another noteworthy thing here is that once a welder is qualified (having made his coupon using a particular WPS), he is not constrained to use only that WPS for production welds. He is free to use any other qualified WPS for production welding, as long as he remains within the boundaries of the ‘range qualified’ of the variables under QW-350.

This finds a mention under second paragraph under QW-304.

4 – Test Was Done on a Test Coupon or on Production Weld?

Section IX requires qualifying the welder through a test coupon as defined under QW-304. Alternatively, Section IX also permits to qualify a welder by carrying out volumetric NDE of the first 6 inches (150 mm) of the production weld made by him.

In other words, an unqualified welder can be directly engaged on the job. Volumetric NDE of the first 6 inches (150 mm) deposited by him on the production weld should be done. The results should be matched with the requirements specified under QW-191.

If results are acceptable, the welder is considered equally qualified as the one qualified through the regular test coupon route.

Note: In my personal opinion, the second option above is not a good option, especially if the job is a code work with high quality requirements.

Tick the appropriate box, depending upon which option was chosen.

4A – Date Welded

In this space, enter the date of completion of weld. This date is important for the purposes of validity of the welder’s qualification.

Since the 2019 edition onwards, the Section IX explicitly mentions in QW-300.1 that the date of validity of the welder’s qualification begins from the date of completion of welding of the test coupon (provided the test results are acceptable).

5 – Specification, Type, and Grade of Base Metal

Mention the type of base metal used, that is – a pipe, or a plate, or any other product form.

Section IX permits using any type for making the qualification coupon. A welder qualified on a pipe can weld on plates too. And a welder qualified on a plate can weld on pipes too, albeit only within the restrictions of QW-461.9.

Note that when it is sought to qualify a welder for all position welding by welding a pipe in both 2G and 5G position, and mechanical testing option is chosen for qualifying the welder, the pipe diameter should be large enough to accommodate the tests indicated in QW-463.2(f) or QW-463.2(g).

6 – Thickness of Base Metal

Base metal thickness is not an essential variable for performance qualifications. So it does not have an impact on the welder’s eligibility to weld on different thicknesses in production. However, the thickness permitted by the WPS only should be used, and the actual thickness used should be recorded on the WPQ record.

Generally, it is enough to record the nominal thickness. Though one may choose to measure the actual thickness used in making the coupon and record it.

7 – Welding Processes

Welding process (GTAW, SMAW, etc.) is an essential variable. That is, a welder can weld only with the process with which he made the test coupon. Therefore, the entries on the space marked 7A and 7B must be identical.

A test coupon can be made with more than one welding process. In such case, the thickness deposited with each process must be measured and recorded. Then, each process should be treated as a separate qualification.

The welder can then weld on production joints using any of the processes individually or in any combination. Each process has to be treated as a separate qualification.

When more than one process is used in the test coupon, it can be recorded as GTAW/SMAW/… etc.

The experience tells that in such cases – it is better to create two different welder qualification records. It is easier to write and read the records thus created. Although, a suitable remark can be added on the WPQ record that the multiple processes were qualified on a single coupon.

8 –Type of Process Used

In this space, the type of welding process – that is, manual, semi-automatic, etc. has to be mentioned.

Note that only the person using manual and semi-automatic welding processes can be called as a welder. A person using machine welding or automatic welding is called a welding operator, according to ASME Section IX.

For a welding operator, the format shown in figure 1 above cannot be used. Instead, the suggested format given at QW-484B has to be used.

A person qualified as a welder cannot weld as a welding operator, even if it is in the same process. A GTAW welder for example is not allowed to operate an automatic GTAW equipment, unless he takes a qualification test for it. The variables defined for welding operator under QW-360 would apply.

However, a welder qualified with a manual welding process is qualified to weld semi-automatic too, in that process.

So, keeping in mind the above – the entries under 8A and 8B should be identical.

9 – Backing (With/Without)

Deletion of backing is an essential variable for performance qualifications. That is, a welder qualified with backing is qualified to weld with backing only. However, a welder qualified without backing is qualified to weld both with and without backing.

Note that a weld made from both sides of a groove is also considered a weld with backing.

9A – In this space, the type of backing (for example: backing ring, backing plate, non-fusing ceramic strip, or weld metal deposited with a different process) used while making the test coupon should be mentioned. If no backing was used, ‘not used’ or ‘none’ can be mentioned.

9B –If backing was used in making the test coupon, this field should show ‘required’, or ‘necessary’, or ‘with backing only’. If no backing was used in making the test coupon, this field can show ‘optional’, or ‘both with and without’, etc.

Note that in case of OFW, it is the opposite. In oxy-fuel welding, addition of backing is an essential variable. So, all discussion above is opposite.

10, 11 – Plate/ Pipe

Tick the appropriate box depending upon what type of base metal was used for preparing the test coupon. See discussion under 5 above.

12 – Thickness/ OD

Determine whether the test coupon was made on a plate or a pipe.

If the Test Was Done on a Plate

Enter thickness of base metal here in 12A, if the base metal used in making the test coupon was a plate. Base metal thickness is not an essential variable for performance qualification. So this thickness does not have any consequence, and serves only for reference.

[However, note that it is not so for OFW. For OFW, base metal thickness is an essential variable (given under QW-403.2). The maximum qualified BM thickness is the thickness of the test coupon. Thus the entries under 12A and 12B would be identical for OFW.]

A welder qualified on aplate weld on apipe too, however, only with some restrictions. These restrictions can be found under QW-461.9. Basically, a welder qualified on a plate can weld on all pipes of OD 24 inches (600 mm) and above.

Also, he can weld on pipes of OD down to 2-7/8 inches (73 mm) but only in restricted positions (as given in QW-461.9).

For example, a welder has been qualified on a plate in 3G position. He can weld on plates and pipes of OD 24 inches. He can also weld on pipes of OD 2-7/8 inch (73 mm) and above, but only in flat position. So, for this welder, in space marked 12B – it may be mentioned as ‘1. Plates & pipes over 24’’ OD; 2. Pipes of OD > 2-7/8’’ (73 mm) in flat position only’.

If the test coupon is a groove weld, besides the above, additionally – ‘fillets of all diameters’ may be added in 12B. This is in accordance with QW-452.6.

There may be several ways to depict this information.

If the Test Was Done on a Pipe

If the base metal used in making the test coupon was a pipe, enter the outer diameter of the pipe in 12A. The pipe outer diameteris an essential variable. So the entry in 12A determines what can be entered in 12B.

When a welder has been qualified on a pipe of a certain OD, he is only qualified to weld on pipes of certain OD. The rules for this have been defined in QW-403.16/ QW-452.3. Refer QW-452.3, and write the qualified OD. If the coupon was a fillet weld, refer QW-452.4 instead of QW-452.3.

For example, the test coupon was made on a pipe of OD 2 inches (50 mm). Per QW-452.3, this welder can weld on pipes of OD 1 inch (25 mm) and above. For this welder, under 12B – ‘Plates; pipes of OD 1’’ and over’ may be written.

13 – P-Number of Base Metal

In 13A, enter P-numbers of the metals used in preparation of the performance qualification test coupon. The P-numbers of various metals can be found in Table QW-422 of Section IX.

Quite Liberal with Regard to Base Metal

There are several notable aspects about base metal in regard to performance qualifications.

One, Section IX’s rules regarding choice of base metal for performance qualification test coupon are quite liberal. Say, the WPS used for making the test coupon specifies a certain P-number. Go to the table given under QW-423.1 (reproduced below), and locate the row in which this P-number is mentioned.

Section IX then allows to use any other P-number mentioned within that row, for making the test coupon. Isn’t this fantastic?

Two, once a welder is qualified, he is eligible to weld on all other base metals listed in column 2 of this table, against that row, including unassigned metals having similar chemical composition to these metals.

So, in 13B – the entry is determined by the second column of the above table.

In a nutshell, in accordance with this table – a welder qualified on any steel is qualified to weld on every other steel. And similar liberty applies for aluminum alloys and titanium alloys. This, it must be said, is quite liberal too.

Three, when a welder has been qualified on an unassigned metal – ordinarily, he would only be qualified to weld on that unassigned metal, in accordance with the above table.

However, QW-423.2 permits to assign a P-number to an unassigned metal too, provided it has matching chemical composition and mechanical properties to an assigned metal. This P-number should be written on the space 13A.

Doing this frees him up to weld on a wide variety of P-numbers in accordance with the above table. The entry in 13B would then be based on the above table.

Note that this is permitted only for the purpose of welder qualifications. This, it has to be said – is a pretty good liberty as well.

In case, no P-number can be assigned to a metal by applying the above provision, then the specification should be written. The welder is then qualified to weld only on that unassigned metal in production – as indicated in the above table. In other words, the entries in 13A and 13B would be identical.

14, 15 – Filler Metal Specification and Classification

Beginners often confuse between the terms specification and classification. Which one is which one?

Here is the answer. Take for example the ubiquitous E7018-1 electrode that is classified under SFA 5.1 of Section II Part C of ASME BPVC. Here, the SFA 5.1 is the specification, and E7018-1 is the classification of the electrode. Under one specification, there are many number of classifications.

Enter the classification and specification of the filler in the spaces 14 and 15. If no filler was used, enter ‘none’, or ‘no filler’ in both these spaces. See 16 below.

16 – F-Number of the Filler

Enter F-number of the filler metal in 16A. F-numbers of various filler metals are given in table QW-432 in Section IX.

In 16B, enter the qualified F-numbers in accordance with QW-404.15, which points us to QW-433.

For example, a welder welded on the test coupon with a F-No. 4 electrode. Per QW-433, he is qualified to weld with F-No. 4 fillers with backing and without backing. He is also qualified to weld with F-No 1, F-No 2, and F-No 3 fillers – but only with backing.

So, for this welder – write ‘1. F-No. 4 – with & without backing; 2. F-No. 1, 2, 3 – with backing only’, in 16B.

The entry in 16B is of course, also influenced by entry in 9B. If 9B reflects ‘with backing only’, the entry in 16B can simply be F-No. 1 through F-No. 4. Else, it can be as described in above paragraph.

If no filler was used, write ‘none’, or ‘no filler’ in 16A.

Remember that deletion or addition of the filler metal is an essential variable (for OFW, GTAW and PAW). So, if the test coupon was made without a filler, the welder is only qualified to weld without a filler metal. Vice-versa, if the welder welded on his test coupon with a filler, he cannot weld in production without a filler.

If ‘none’ or ‘no filler’ is entered in 16A, enter the same in 16B too.

17 – Consumable Inserts

Consumable inserts are generally used with only GTAW and PAW processes.

If a consumable insert was used in making the qualification test coupon, enter ‘Used’ in 17A. If no insert is used, enter ‘not used’.

Addition or deletion of inserts is an essential variable for GTAW and PAW processes. It has been addressed in QW-404.22. A welder qualified with an insert is only qualified to weld with an insert. He is also qualified to weld joints with ordinary backing and also joints that are welded from both sides.

Conversely, a welder needing to weld with an insert in a production joint must have been qualified with an insert in his performance qualification test.

If ‘used’ has been entered in 17A, enter ‘required’, or ‘with insert’ in 17B. Additionally, ‘welds with backing, double-welded joints’ may also be entered in 17B.

If ‘not used’ has been entered in 17A, enter ‘inserts not permitted’ in 17B.

If the welding process is other than GTAW or PAW, enter ‘NA’ in both 17A and 17B.

18 – Filler Metal Product Form (for GTAW or PAW)

Change of filler metal product form (for e.g. bare or flux cored or flux coated or powder, etc.) from one form to another is an essential variable for welder performance qualifications with GTAW and PAW processes.

In 18A, write the product form of the filler metal used in making the performance qualification test coupon. In 18B, write the same thing.

If the welding process is other than GTAW or PAW, enter ‘NA’ in both 18A and 18B.

19 – Deposit Thickness

Deposited weld metal thickness is an essential variable. It has been addressed in QW-404.30, which points us to QW-452. Per QW-452, the qualified weld metal thickness is generally 2t (where ‘t’ is deposited thickness in test coupon).

However, if at least ½ inch (13 mm) of weld metal with a minimum of three layers have been deposited in the test coupon, the qualified weld metal thickness is unlimited.

For oxy-fuel welding process, the maximum qualified weld metal thickness is equal to the thickness of the test coupon.

For GMAW-short circuiting process, and when deposited weld thickness is less than ½ inch (13 mm), the maximum qualified weld metal thickness is equal to 1.1 times the deposited thickness in test coupon.

[Note (1): This restriction does not apply for fillet welds [IX-95-28]. If the test coupon is a fillet weld, it qualifies fillet welds on all base metal thicknesses (QW-452.5). If a groove weld is used to support fillet welds, it qualifies fillet welds on all base metal thicknesses (QW-452.6).
Note (2): Generally, whenever there are two clauses in code addressing the same thing, the stringent of the two takes precedence over the other. This is one of the rare instances when the stringent one (QW-404.32) does not dominate the lenient one (QW-452.5/QW-452.6)].

When deposited thickness is more than ½ inch (13 mm), the unlimited rule discussed in above paragraph applies.

In 19A, write the actual deposited weld metal thickness in the test coupon. Tick the appropriate box depending upon whether a minimum of three layers were deposited in making the test coupon or not.

In 19B, write the qualified weld metal thickness in accordance with above paragraphs.

Keep in mind that if multiple qualifications are done in the same coupon (that is, multiple welders, or a single welder with multiple processes, or a single welder with different sets of variables), the deposited thickness of each qualification should be measured and recorded individually in 19A.

The corresponding qualified deposit thicknessesshould be written in 19B then.

20 – Position Qualified

Welding Position is an essential variable for welding performance qualifications.

In 20A, enter the position (that is, 1G, 2G, …etc.) in which the test coupon was made. Remember that 1G position is not the same thing as the flat position. So in 20A, indicate the position by way of 1G, 2G, etc. only, and not as flat, horizontal, etc.

I have covered this subject in some detail in another article, that may be found here.

In 20B, enter the positions for which the welder is qualified to weld in production. This judgment has to be made in accordance with QW-461.9.

Note that, in 20B – the positions have to be depicted as flat/ horizontal/ overhead/ vertical etc. (and not as 1G, 2G, etc.).

21 – Vertical Progression

QW-405.3 is an essential variable for welder performance qualifications (except OFW and semi-automatic SAW). Per QW-405.3, a change from upward to downward or downward to upward in any pass of a vertical weld is an essential variable (that is, it requires requalification), except that cover or wash pass may be deposited up or down.

This restriction is not applicable on root passes too if the root passes are going to be removed to sound metal in preparation for welding from the second side.

In 21A, indicate whether the test coupon involved welding in vertical progression. The positions that involve vertical progression are 3G, 3F, 5G, 5F, 6G, 6F. Indicate the progression of welding, i.e. uphill or downhill. If different passes of the coupon involved different progressions, indicate accordingly.

In 21B, enter the same data as entered in 21A.

If the test coupon did not involve vertical welding, indicate NA in both 21A and 21B. Although, the restriction of QW-405.3 is not applicable to cover pass or wash pass or root pass (if removed to sound metal on back side), this exemption is not generally mentioned on the WPQR. Although, it would be quite fine if was mentioned too.

22 – Type of Fuel Gas (for OFW)

This filed is only required to be filled when the welding process involved is oxy-fuel welding. Type of fuel gas used in OFW is an essential variable for welder qualification. That is, a change of gas from, say acetylene to propane etc., will require a requalification of the welder.

In 22A – enter the fuel gas used when making the test coupon. Make an identical entry in 22B.

23 – Backing Gas for GTAW, PAW and GMAW

Deletion of backing gas is an essential variable for welder qualifications with GTAW, GMAW, and PAW processes. However, requalification is not necessary if the production weld is made with a backing, or welded from both sides. This exemption does not apply when welding titanium and its’ alloys and zirconium and its’ alloys.

Note that only deletion of backing gas is essential variable (addition is not). That is, if the test coupon was made without use of a backing gas, the welder is qualified to make welds in production both with and without backing gas.

In 23A, enter ‘used’ if gas was used for shielding the weld from the back side, during test coupon welding. If gas was not used, write ‘not used’.

In 23B, write ‘with backing gas only’, or ‘required’ – if the entry in 23A is ‘used’.

If 23A shows ‘not used’, write ‘optional’ in 23B.

If the welding process is other than GTAW, GMAW or PAW, write ‘Not applicable’ in both 23A and 23B.

24 – Metal Transfer Mode in GMAW

In GMAW, a change from globular, spray or pulsed spray transfer mode to short-circuiting transfer mode or vice versa is an essential variable.

That is, if the test coupon was made using short-circuit transfer mode, the welder is only qualified to deposit with short circuit transfer mode. He is not qualified to deposit with other above-mentioned transfer mode.

And, if the test coupon was made with any of globular, spray or pulsed spray transfer modes, the welder is qualified to deposit with any mode among these three modes. He is not qualified to deposit with short-circuit mode of metal transfer.

In 24A, enter the type of transfer mode done in the test coupon. If ‘short-circuiting’ is written in 24A, enter the same in 24B as well. If any among globular, spray or pulsed spray is entered in 24A, write ‘globular, spray, and pulsed spray’ in 24B.

Note that all variables of GMAW process are also ditto applicable to FCAW process too.

If the welding process involved is any other than GMAW or FCAW, enter ‘Not applicable’ in both 24A and 24B.

25 – Current Type in GTAW Process

In GTAW process, a change from alternating current to direct current is an essential variable. Also, if direct current is used, a change from straight polarity to reverse polarity and vice versa is an essential variable as well.

In 25A, enter the type of current used. If DC is used, enter polarity too, i.e. SP or RP. Enter the same in 25B too.

If the process is any other than GTAW, enter ‘Not applicable’.

26 – Visual Examination of the Completed Weld

QW-304 permits to qualify the welder through either the mechanical test and visual testing option, or through the volumetric NDE option. The completed weld should show no cracks and should show complete penetration of the weld, and complete fusion of the weld metal with the base metal.

Note that for a plate coupon all surfaces are required to be examined, except the portion marked ‘discard’. For pipe coupons, entire circumference is required to be examined, both from inside and outside.

If the welded coupon meets these criteria, write ‘acceptable’ in 26.

Note that although the Section IX does not require visual testing when the qualification is done through volumetric NDE option, it is still advisable to do it. It is a quick inspection, and yields useful information. Record the results in the format.

27 –Type of Bend Specimen

Tick the type of specimen chosen for qualification.

The QW-452.1(a) requires one transverse face bend and one transverse root bend for weld metal thicknesses less than 3/8 inch (10 mm). Two side bends are required for any thickness between 3/8 inch (10 mm) to ¾ inch (19 mm).

Instead of two side bends, one root bend and one face bend can also be used. Above ¾ inch (19 mm) weld metal thickness, two side bends are required.

Note that the side bend specimens are required to be prepared in accordance to QW-462.2, while root bend and face specimens are required to be prepared in accordance to QW-462.3(a).

It is also to be noted that if the two base metals to be joined are quite different in ductility, or if the weld metal being is used has a different ductility than the base metal(s), then Section IX permits use of longitudinal bend tests too (QW-161.5).

Only root bend and face bends are allowed (no side bends). These longitudinal bend specimens must be prepared in accordance to QW-462.3(b).

The downside of using longitudinal bend specimens is that a longer length of the test coupon is required.

28 – Bend Tests for Corrosion Resistance Overlay

If the bend specimens are carved from a test coupon welded with a corrosion resistance overlay, the bend specimens are required to conform to QW-462.5(c) (for pipes) or QW-462.5(d) (for plates).

Tick the appropriate box, based on whether the test coupon was a plate or a pipe.

29 – Test specimens for Hard Facing Overlay

When the performance qualification is for a hard facing overlay, Section IX requires evaluation of the suitably etched cross section, and requires freedom from cracks, lack of fusion. Chemical analysis and hardness are also required to be checked at locations specified in WPS.

Tick the appropriate box, based on whether the test coupon was a plate or a pipe.

30, 31 – Bend Test Results

Enter the type of bend specimen used and the test results.

Discontinuities of size lower than 1/8 inch (3 mm) are permitted on the convex surface of the specimen (for cladding specimens the size permitted is 1/16 inch (1.5 mm)). The acceptance criteria is defined in detail in QW-163.

In 31, enter the size and number of discontinuities observed, if any. Write also the disposition of the test, that is – ‘acceptable’ or ‘not acceptable’.

32, 33, 34 – Volumetric NDE Results

Instead of visual and mechanical testing, the welder qualification can also be done through volumetric NDE. Any among radiography or ultrasonic testing is acceptable. Note that a weld length of at least 6 inches (150 mm) is required to qualify a welder.

The acceptance criteria for volumetric NDE is as per QW-191.

The findings of the NDE examination, and disposition (that is, acceptable or not acceptable) should be mentioned in 32. Among 33 or 34, tick the appropriate box to indicate the NDE method adopted to evaluate he test coupon.

Alongside the disposition, the test report number also may be written. Also, although it is not mandatory, it is advisable to annex the test report along with this WPQ record itself. In my organization, the test report is annexed to the WPQR.

The RT film is generally not annexed to the WPQR, because the film suffers a deterioration in quality over a period of time.

If the testing of test coupon was done through mechanical + visual testing, write NA in all three – 32, 33, 34.

35, 36, 37, 38–Fillet Weld Fracture Test

When the performance qualification is done through a fillet weld test coupon, fracture test and macro-graph are the two tests required. The specimen preparation for both these tests must be done in accordance with QW-462.4(b) (when the base material is a plate to plate) or QW-462.4(c) (when the base material is a plate-to-pipe or pipe-to-pipe). The description is also given in QW-181.2.

The acceptance criteria for fracture test is given in QW-182.

In 35, write the disposition of the fracture test – that is, acceptable or not acceptable. In 36, write the defect type, length and percentage of the defect lengths observed. For example, three inclusions and two porosities of collective length 3/16 inch (5 mm), etc.

In 37, 38 – tick the appropriate box indicating the type of fillet weld done. Tick 37 if the test coupon was a plate-to-plate coupon. Tick 38 if the test coupon was plate-to-pipe or pipe-to-pipe.

39, 40, 41 – Macro examination for Fillet Weld Coupons

Macro Examination is the second test besides fracture test, when the performance qualification of a welder is done through a fillet weld test coupon. The specimen preparation is required to be done in accordance to QW-181.2, QW-462.4(b) & (c). The acceptance criteria for the test is defined under QW-184.

The weld metal & HAZ should show complete fusion and freedom from cracks. The concavity or convexity should not exceed 1/16 inch (1.5 mm). And difference in leg lengths of the fillet should not exceed 1/8 inch (3 mm).

In 39, enter disposition of the test, that is – acceptable or not acceptable. In 40 and 41, enter fillet leg lengths and convexity or concavity.

42 – Other Tests

The welding engineer should always bear in mind that the tests asked by Section IX are only the minimum requirements. Based on the needs of an application, other tests may be included for qualifying a welder.

For example, in my work place – longitudinal face bend is also a required test for performance qualification of a welder for corrosion-resistance overlay welding. This test is not required by Section IX.

43, 44 –Person Who Evaluated the RT Film/ Mechanical Test Specimens

Here in 43, enter the name of the person who evaluated the RT film. Note that the personnel who do this evaluation are required to be appropriately qualified in accordance with QW-191.

If the qualification is done through the mechanical testing option, the person who evaluates the bent specimen must ensure that the specimen preparation was done in accordance to QW-161.

Section IX permits to sub-contract thepreparation of the test specimens from the completed test joint, and performance of mechanical testing or NDE, provided the organization accepts full responsibility for this work.

In 44, enter the lab/company in which the person who evaluates the film/specimens is employed.

45, 46 – Mechanical Testing

In 45, enter the name of the person who carries out the mechanical testing. Note that the agency/person that does the mechanical testing must ensure that the testing was done in accordance with QW-162 (which leads us to jigs illustrated in QW-466.1), and the acceptance is based on QW-163.

In 46, enter the test report number. As with test report for NDE exam, the mechanical testing report may be annexed with the WPQR itself.

47 – Supervision of Welding

The Section IX requires that the welder who makes the test coupon must be under the supervision and control of the qualifying organization. Who must do this supervisory role?

While Section IX does not address this, it does say (in 2019 edition onwards) that the person performing supervision and control must be designated, and must have knowledge on Section IX, and must have knowledge on the scope and complexity of the qualification being done.

In my opinion, this role can only be filled by the responsible welding engineer. Therefore, in 47, enter the name of the welding engineer.

Note that the welding engineer must be an employee of the qualifying organization. Section IX expressly prohibits production of test coupons under the supervision and control of another organization.

Note that the welding engineer is not required to witness all of the welding. However, he is a responsible person. He must ensure that the data that would be eventually recorded on the WPQR is a true reflection of the events that occurred during production of the test coupon.

48, 49, 50 – Certification

Certification of the WPQR is an important aspect of the qualification exercise. In 48, enter the name of the qualifying organization. This is the organization that is going to manufacture/ fabricate the code compliant equipment. The organization is the owner of the qualification.

In 49, enter the name and signature of the certifying individual. This person need not be the same as the one that supervised the welding of the test coupon. In my organization, these two people are the same person, that is – the welding engineer.

In 50, enter the date of declaration of test results. Commonly, this date is a few days after the date of completion of welding. Sometimes however, the mechanical testing can take up to several weeks, in which case this date would be substantially later to the date of welding.

What should be the starting date of the welder’s six-month validity before it expires (per QW-322)? Should it be date of test results? Or, should it be date of welding? There was controversy around this earlier. However, in 2019 edition onwards, Section IX has made it clear in QW-301.1, that the date of validity begins from the date of completion of welding.

So, this was all I had to offer on the subject of writing a welder performance qualification record, or WPQR. Please share your thoughts, observations, questions in the comments section below. Thanks for reading.

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