API 510 Chapter 14- Welding Qualifications and ASME IX
14.1 Module introduction
The purpose of this chapter is to familiarize you with the principles and requirements of welding qualification documentation. These are the Weld Procedure Specification (WPS), Procedure Qualification Record (PQR) and Welder Performance Qualification (WPQ). The secondary purpose is to define the essential, non-essential and supplementary essential variables used in qualifying WPSs.
ASME section IX is a part of the ASME Boiler Pressure Vessel code that contains the rules for qualifying welding procedures and welders. It is also used to qualify welders and procedures for welding to ASME VIII.
14.1.1 Weld procedure documentation: which code to follow?
API 510 (section 188.8.131.52.1) requires that repair organizations must use welders and welding procedures qualified to ASME IX and maintain records of the welding procedures and welder performance qualifications. ASME IX article II states that each Manufacturer and Contractor shall prepare written Welding Procedure Specifications (WPSs) and a Procedure Qualification Record (PQR), as defined in section QW-200.2.
14.2 Formulating the qualification requirements
The actions to be taken by the manufacturer to qualify a WPS and welder are done in the following order (see Fig. 14.1):
Step 1: qualify the WPS . A preliminary WPS (this is an unsigned and unauthorized document) is prepared specifying the ranges of essential variables, supplementary variables (if required) and nonessential variables required for the welding process to be used. . The required numbers of test coupons are welded and the ranges of essential variables used recorded on the PQR. . Any required non-destructive testing and/or mechanical testing is carried out and the results recorded in the PQR. . If all the above are satisfactory then the WPS is qualified using the documented information on the PQR as proof that the WPS works. The WPS (see Fig. 14.2) is signed and authorized by the manufacturer for use in production. Step 2: qualify the welder. The next step is to qualify the welder by having him weld a test coupon to a qualified WPS. The essential variables used, tests and results are noted and the ranges qualified on a Welder Performance Qualification (WPQ) (see Fig. 14.3). Note that ASME IX does not require the use of preheat or PWHT on the welder test coupon. This is because it is the skill of the welder and his ability to follow a procedure that is being tested. The pre- and PWHT are not required because the mechanical properties of the joint have already been determined during qualification of the WPS.
14.2.1 WPSs and PQRs: ASME IX section QW-250
We will now look at the ASME IX code rules covering WPSs and PQRs. The code section splits the variables into three groups:
- Essential variables
- Non-essential variables
- Supplementary variables
These are listed on the WPS for each welding process. ASME IX section QW-250 lists the variables that must be specified on the WPS and PQR for each process. Note how this is a very long section of the code, consisting mainly of tables covering the different welding processes. There are subtle differences between the approaches to each process, but the guiding principles as to what is an essential, non-essential and supplementary variable are much the same.
14.2.2 ASME IX welding documentation formats
The main welding documents specified in ASME IX have examples in non-mandatory appendix B section QW-482. Strangely, these are not included in the API 510 exam code document package but fortunately two of them, the WPS and PQR, are repeated in API 577 (have a look at them in API 577 appendix C). Remember that the actual format of the procedure sheets is not mandatory, as long as the necessary information is included.
The other two that are in ASME IX non-mandatory appendix B (the WPQ and Standard Weld Procedure Specification (SWPS)) are not given in API 577 and are therefore a bit peripheral to the API 510 exam syllabus.
14.3 Welding documentation reviews: the exam questions
The main thrust of the API 510 ASME IX questions is based on the requirement to review a WPS and its qualifying PQR, so these are the documents that you must become familiar with. The review will be subject to the following limitations (to make it simpler for you):
- The WPS and its supporting PQR will contain only one welding process.
- The welding process will be SMAW, GTAW, GMAW or SAW and will have only one filler metal.
- The base material P group number will be either P1, P3, P4, P5 or P8.
Base materials are assigned P-numbers in ASME IX to reduce the amount of procedure qualifications required. The P-number is based on material characteristics like weldability and mechanical properties. S-numbers are the same idea as Pnumbers but deal with piping materials from ASME B31.3.
14.3.1 WPS/PQR review questions in the exam
The API 510 certification exam requires candidates to review a WPS and its supporting PQR. The format of these will be based on the sample documents contained in annex B of ASME IX. Remember that this annex B is not contained in your code document package; instead, you have to look at the formats in API 577 appendix B, where they are shown (they are exactly the same).
The WPS/PQR documents are designed to cover the parameters/variables requirements of the SMAW, GTAW, GMAW and SAW welding processes. The open-book questions on these documents in the API exam, however, only contain one of those welding processes. This means that there will be areas on the WPS and PQR documents that will be left unaddressed, depending on what process is used. For example, if GTAW welding is not specified then the details of tungsten electrode size and type will not be required on the WPS/PQR.
In the exam questions, you will need to understand the variables to enable you to determine if they have been correctly addressed in the WPS and PQR for any given process
14.3.2 Code cross-references
One area of ASME IX that some people find confusing is the numbering and cross-referencing of paragraphs that takes place throughout the code. Figure 14.4 explains how the ASME IX numbering system works.
14.4 ASME IX article I
Article 1 contains less technical ‘meat’ than some of the following articles (particularly articles II and IV). It is more a collection of general statements than a schedule of firm technical requirements. What it does do, however, is cross reference a lot of other clauses (particularly in article IV), which is where the more detailed technical requirements are contained.
From the API exam viewpoint, most of the questions that can be asked about article I are:
- More suitable to closed-book questions than open-book ones .
- Fairly general and ‘commonsense’ in nature
Don’t ignore the content of article I. Read the following summaries through carefully but treat article I more as a lead-in to the other articles, rather than an end in itself.
This section tells you five things, all of which you have met before. There should be nothing new to you here. They are:
- A Weld Procedure Specification (WPS) has to be qualified (by a PQR) by the manufacturer or contractor to determine that a weldment meets its required mechanical properties.
- The WPS specifies the conditions under which welding is performed and these are called welding ‘variables’.
- The WPS must address the essential and non-essential variables for each welding process used in production.
- The WPS must address the supplementary essential variables if notch toughness testing is required by other code sections.
- A Procedure Qualification Record (PQR) will document the welding history of the WPS test coupon and record the results of any testing required.
A welder qualification (i.e. the WPQ) is to determine a welder’s ability to deposit sound weld metal or a welding operator’s mechanical ability to operate machine welding equipment.
14.5 Section QW-140 types and purposes of tests and examinations
Section QW-141: mechanical tests
Mechanical tests used in procedure or performance qualification are as follows:
QW-141.1: tension tests (see Fig. 14.5). Tension tests are used to determine the strength of groove weld joints.
QW-141.2: guided-bend tests (see Fig. 14.6). Guided-bend tests are used to determine the degree of soundness and ductility of groove-weld joints.
QW-141.3: fillet-weld tests. Fillet weld tests are used to
determine the size, contour and degree of soundness of fillet welds.
QW-141.4: notch-toughness tests. Tests are used to determine the notch toughness of the weldment.
14.6 ASME IX article II Article II
contains hard information about the content of the WPS and PQRs and how they fit together. In common with article I, it cross-references other clauses (particularly in article IV). From the API examination viewpoint there is much more information in here that can form the basis of open-book questions, i.e. about the reviewing of WPS and PQR. ASME IX article II is therefore at the core of the API examination requirements.
Section QW-200: general This gives lists of (fairly straightforward) requirements for the WPS and PQR:
QW-200.1 covers the WPS. It makes fairly general ‘principle’ points that you need to understand (but not remember word-for-word).
QW-200.2 covers the PQR again. It makes fairly general ‘principle’ points that you need to understand (but not remember word-for-word).
QW-200.3: P-numbers. P-numbers are assigned to base metals to reduce the number of welding procedure qualifications required. For steel and steel alloys, group numbers are assigned additionally to P-numbers for the purpose of procedure qualification where notch-toughness requirements are specified.
Now try these familiarization questions, using ASME IX articles I and II to find the answers.
14.7 ASME IX articles I and II familiarization questions
14.8 ASME IX article III
Remember that WPQs are specific to the welder. While the content of this article is in the API 510 syllabus it is fair to say that it commands less importance than articles II (WPSs and PQRs and their relevant QW-482 and QW-483 format forms) and article IV (welding data).
Section QW-300.1 This article lists the welding processes separately, with the essential variables that apply to welder and welding operator performance qualifications. The welder qualification is limited by the essential variables listed in QW-350, and defined in article IV Welding data, for each welding process. A welder or welding operator may be qualified by radiography of a test coupon or his initial production welding, or by bend tests taken from a test coupon. Look at these tables below and mark them with post-it notes:
- Table QW-353 gives SMAW essential variables for welder qualification.
- Table QW-354 gives SAW essential variables for welder qualification.
- Table QW-355 gives GMAW essential variables for welder qualification.
- Table QW-356 gives GTAW essential variables for welder qualification.
Section QW-351: variable for welders (general) A welder needs to be requalified whenever a change is made in one or more of the essential variables listed for each welding process. The limits of deposited weld metal thickness for which a welder will be qualified are dependent upon the thickness of the weld deposited with each welding process, exclusive of any weld reinforcement.
In production welds, welders may not deposit a thickness greater than that for which they are qualified.
14.9 ASME IX article IV
Article IV contains core data about the welding variables themselves. Whereas article II summarizes which variables are essential/non-essential/supplementary for the main welding processes, the content of article IV explains what the variables actually are. Note how variables are subdivided into procedure and performance aspects.
Section QW-401: general Each welding variable described in this article is applicable as an essential, supplemental essential or non-essential variable for procedure qualification when referenced in QW-250 for each specific welding process. Note that a change from one welding process to another welding process is an essential variable and requires requalification.
Section QW-401.1: essential variable (procedure) This is defined as a change in a welding condition that will affect the mechanical properties (other than notch toughness) of the weldment (for example, change in P-number, welding process, filler metal, electrode, preheat or post-weld heat treatment, etc.).
Section QW-401.2: essential variable (performance) A change in a welding condition that will affect the ability of a welder to deposit sound weld metal (such as a change in welding process, electrode F-number, deletion of backing, technique, etc.).
Section QW-401.3: supplemental essential variable (procedure) A change in a welding condition that will affect the notchtoughness properties of a weldment (e.g. change in welding process, uphill or downhill vertical welding, heat input, preheat or PWHT, etc.).
Section QW-401.4: non-essential variable (procedure) A change in a welding condition that will not affect the mechanical properties of a weldment (such as joint design, method of back-gouging or cleaning, etc.)
Section QW-401.5 The welding data include the welding variables grouped as follows:
- QW-402 joints
- QW-403 base metals
- QW-404 filler metal
- QW-405 position
- QW-406 preheat
- QW-407 post-weld heat treatment
- QW-408 gas
- QW-409 electrical characteristics
- QW-410 technique
Section QW-420.1: P-numbers P-numbers are groupings of base materials of similar properties and usability. This grouping of materials allows a reduction in the number of PQRs required. Ferrous Pnumber metals are assigned a group number if notch toughness is a consideration.
Section QW-420.2: S-numbers (non-mandatory) S-numbers are similar to P-numbers but are used on materials not included within ASME BPV code material specifications (section II). There is no mandatory requirement that S-numbers have to be used, but they often are. Note these two key points:
- For WPS a P-number qualifies the same S-number but not vice versa.
- For WPQ a P-number qualifies the same S-number and vice versa.
Section QW-430: F-numbers The F-number grouping of electrodes and welding rods is based essentially on their usability characteristics. This grouping is made to reduce the number of welding procedure and performance qualifications, where this can logically be done.
Section QW-432.1 Steel and steel alloys utilize F-1 to F-6 and are the most commonly used ones.
Section QW-492: definitions QW-492 contains a list of definitions of the common terms relating to welding and brazing that are used in ASME IX.
Try these ASME IX articles III and IV familiarization questions. You will need to refer to your code to find the answers.
14.10 ASME IX articles III and IV familiarization questions
14.11 The ASME IX review methodology
One of the major parts of all the API in-service inspection examinations is the topic of weld procedure documentation review. In addition to various ‘closed-book’ questions about welding processes and techniques, the exams always include a group of ‘open-book’ questions centred around the activity of checking a Weld Procedure Specification (WPS) and Procedure Qualification Record (PQR).
Note the two governing principles of API examination questions on this subject: .
- The PQR and WPS used in exam examples will only contain one welding process and filler material.
- You need only consider essential and non-essential variables (you can ignore supplementary variables).
The basic review methodology is divided into five steps (see Fig. 14.7). Note the following points to remember as you go through the checklist steps of Fig. 14.7:
- The welding process is an essential variable and is likely to be SMAW, GTAW, GMAW or SAW.
- Non-essential variables do not have to be recorded in the PQR (but may be at the manufacturer’s discretion) and must be addressed in the WPS.
- Information on the PQR will be actual values used whereas the WPS may contain a range (e.g. the base metal actual thickness shown in a PQR may be 1 /2 in, while the base metal thickness range in the WPS may be 3/16 in–1 in). .
- The process variables listed in tables QW-252 to QW-265
are referred to as the ‘brief of variables’ and must not be used on their own. You must refer to the full variable requirements referenced in ASME IX article 4 otherwise you will soon find yourself in trouble.
The base material will be either P-1, P-3, P-4, P-5 or P-8 (base materials are assigned P-numbers in ASME IX to reduce the amount of procedure qualifications required).
14.12 ASME IX WPS/PQR review: worked example
The following WPS/PQR is for an SMAW process and contains typical information that would be included in an exam question. Work through the example and then try the questions at the end to see if you have understood the method.
Figures 14.8 and 14.9 show the WPS and PQR for an SMAW process. Typical questions are given, followed by their answer and explanation.