CWI WPS, PQR and Welder Qualification Study Guide

What this domain covers

Welding Performance is about the documents and tests that show a weld can be made correctly and that a welder can make it. Expect questions on what a welding procedure specification (WPS) and a procedure qualification record (PQR) are. Other questions ask what essential variables mean, how welders are qualified and what the inspector checks. Examples come mainly from ASME Section IX and AWS D1.1, two widely used qualification documents.

The documents to know

• Welding procedure specification (WPS): the instructions. It gives welders the variables for a specific application so results are repeatable.
• Procedure qualification record (PQR): the evidence. It records the actual values used to weld a test coupon and the results of testing it.
• Welder performance qualification record (WPQ): proof that a particular welder passed a test.

A PQR is a factual record. You cannot change its welding data after the test, even if production used different values. Only editorial corrections are allowed. To cover new values, the WPS must stay within what the PQR supports, or a new PQR must be made.

Under Section IX, one WPS can be supported by more than one PQR, and one PQR can support several WPSs.

Procedure versus performance qualification

The two tests answer different questions:

• Procedure qualification shows that a weldment made with the procedure can have the required mechanical properties. It usually uses tension and bend tests.
• Performance qualification shows that a welder can deposit sound weld metal following a qualified (or prequalified) WPS. It usually uses bend tests or radiography.

A qualified welder does not replace a qualified procedure, and a qualified procedure does not replace a qualified welder.

Essential, nonessential and supplementary variables

• An essential variable affects the weldment's mechanical properties. Changing it beyond the code's limits requires requalification.
• A nonessential variable can be changed by revising the WPS, with no new test. Groove design and interpass cleaning method are usually nonessential for procedures in Section IX.
• A supplementary essential variable in Section IX matters only when the construction code requires notch toughness (impact) testing. An increase in heat input is the usual example, because higher heat input coarsens grains and can lower toughness.

Grouping to reduce testing

Section IX groups materials so one test can cover many:

• P-numbers group base metals with similar composition, weldability and mechanical properties.
• F-numbers group filler metals by usability, meaning how hard they are to weld with. For shielded metal arc welding (SMAW), low-hydrogen electrodes such as E7018 are F4 and cellulosic electrodes such as E6010 are F3.
• A-numbers group ferrous weld metal by chemical composition.

Welder qualification rules

Rules to know:

• Continuity: under Section IX, a welder's qualification for a process expires after 6 months without using it. D1.1 has a similar 6-month rule. Qualification can also be revoked when there is a specific reason to question the welder's ability.
• Backing: deleting backing is an essential variable for welders. A welder qualified without backing may weld with backing, but not the reverse.
• Positions (defined in the terminology guide): a 6G pipe test qualifies groove welding in all positions within the code's limits. Under D1.1, a 3G plate test qualifies flat, horizontal and vertical, and adding 4G covers overhead.
• Radiography in place of bends: many codes allow radiographic testing (RT) of the test coupon instead of bend tests. Section IX and D1.1 are two of them. The exception is short-circuiting gas metal arc welding (GMAW). Its typical flaw, incomplete fusion, is hard to see on a radiograph.

D1.1 welder test plates

Memorize these two D1.1 test plates:

Side bends are used on thicker plate because they expose the whole weld thickness in a specimen thin enough to bend. Face, root and side bends are explained in the destructive testing guide.

Prequalified and standard procedures

AWS D1.1 prequalified WPSs are exempt from qualification testing when every prequalification condition is met. The conditions cover listed processes, base metals, filler metals, joint details, preheat and other variables. The WPS still has to be written. Short-circuiting GMAW cannot be prequalified. Welders using a prequalified WPS still need to be qualified. Finding these rules in the code book is covered in the Part C qualification guide.

AWS Standard Welding Procedure Specifications (SWPSs), published in the AWS B2.1 series, are WPSs backed by PQRs. Some codes accept them, including Section IX under conditions in its Article V. A user can then adopt them within their limits without making their own PQRs.

Who is responsible

Under Section IX, each manufacturer or contractor is responsible for the welding its organization does. It must qualify its own procedures and welders and certify the records. The employer keeps welder qualification records and makes them available to the inspector. Under D1.1, documented qualifications from a previous employer may be accepted with the Engineer's approval.

The inspector's role

During a procedure qualification test, the inspector:

• Witnesses the welding.
• Records the actual variables used.
• Observes specimen removal and testing.

The inspector does not weld the coupon, choose the variables or decide which specimens count.

Before production, the inspector compares each welder's record with the job. The check covers process, position, thickness and diameter range, filler metal group, backing and other essential variables. Work by an unqualified welder does not comply with the code, however good it looks.

How to study this domain

Practice with a sample WPS, PQR and welder record side by side. Pick a production situation, such as a new position or thickness, and work out whether the existing papers cover it. Exam questions ask you to reason the same way.

Mark J. Curry's tip: when a question mentions a change, first ask whether it affects the procedure, the welder or both. Then find the rule for that one.

Work through the free welding performance practice questions. To see which Part A topic to study first, take the free CWI diagnostic test.

Sources

The Welding Performance questions cite these documents, by document and, where we can confirm it, chapter or section. We never reproduce them.

1. ASME BPVC Section IX (17 questions)
2. AWS D1.1 (9 questions)
3. AWS A3.0 (1 question)
4. AWS B2.1 (1 question)

Found a mistake? Use "Report a problem" under any question, and Mark J. Curry checks it.

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