Most API 653 candidates lose welding marks on swapped words, not on weld technique. The wrong answer is often a true statement about the wrong document.
What does each welding term mean on the exam?
Domain II asks you to review three records: the Welding Procedure Specification (WPS), the Procedure Qualification Record (PQR) and the Welder Performance Qualification (WPQ). Each one answers a different question.
| Term | Question it answers | Where it shows up |
|---|---|---|
| PQR | What was actually done on the test coupon, and did it pass? | Values used, mechanical test results, signed and dated |
| WPS | How may production welding be done? | Ranges and variables, cites its PQR |
| WPQ | Can this welder make this weld? | One named welder, coupon welded to a qualified WPS |
| Essential variable | Which change forces new qualification testing? | Addressed on the WPS and PQR |
| Non-essential variable | Which change only needs the WPS revised? | Addressed on the WPS |
Two more words belong to the exam’s own fence. Supplementary essential variables are out, and so are Charpy impact requirements. If a question seems to need either, you have misread the question.
API 653 — Settlement, thickness, interval — one calculation, one number. Watch on YouTube · CertCrafter The channel’s short on one calculation from settlement to thickness to interval is a useful change of pace from the paperwork side of the exam.
Is a range a PQR thing or a WPS thing?
A WPS thing. This is the swap that costs the most points.
The PQR is evidence. A coupon was welded under one set of conditions and tested, and the record states those conditions as they were. The WPS then tells the welder the limits for production. If a PQR shows a preheat or a thickness as a range, it no longer proves that one specific set of conditions produced a passing coupon.
The free question on a PQR for SMAW on A283 Grade C plate tests this exactly. It shows ranges on the qualification record and asks what the inspector should conclude. The answer is that the record must carry the values actually used, since ranges belong on the specification.
Essential or non-essential: which change needs new testing?
An essential variable is one whose change affects the properties of the weld, so a change there calls for a new qualification record and new testing. A non-essential variable can change without that. The WPS is revised and no new coupon is welded.
The body of knowledge asks you to determine whether all required essential and non-essential variables have been properly addressed. Notice the verb. You are not recomputing anything, you are checking that each variable has been dealt with in the right document.
Candidates also read “address” as “match”. A WPS can allow a wider range than one PQR value, as long as the variable is handled the way Section IX allows. Your job is to know which kind of variable you are looking at before you decide what a change does.
How do inspectors use these words on a repair job?
Before work starts on a shell repair, the contractor sends a package. An experienced inspector reads it as three separate questions and refuses to let one document answer for another.
A signed PQR does not qualify a welder. A WPQ does not approve a procedure. A WPS with a nice list of ranges proves nothing if the PQR it cites is missing from the package.
The common field finding is a broken link, not a bad weld: a WPS that cites a PQR number nobody can produce, a welder qualified on a different process, or a record with no signature. Each of those stops the job on paper, whatever the weld might look like later.
Worked example: sort the statements into the right record
These items are invented for practice. A package arrives for a shell insert repair. You sort six statements from it, one by one.
- “Preheat shown as a range, thickness shown as a range.” That is WPS language. If it sits on the PQR, flag it.
- “Coupon tensile and bend results listed.” That is PQR content. Check the tests are the right ones and the results acceptable.
- “Welder J. Moreno passed a coupon welded to WPS-14.” That is a WPQ. Check WPS-14 was itself qualified.
- “WPS-14 cites PQR-07.” Good, now confirm PQR-07 is in the package and is signed and dated.
- “The WPS covers SMAW and GMAW.” Only one process may appear on a single WPS in the exam’s review scope. Stop and re-read.
- “Base metal is A283 Grade C.” That is a P-No. 1 plate, the group the review is limited to.
Notice how little arithmetic is involved. The whole exercise is deciding which document each statement belongs to.
The API 653 Complete Exam Kit works more of these under timed conditions, with every answer explained.
Which consumable terms get confused?
Exposed electrodes are the classic. A low hydrogen electrode such as E7018 is chosen because its coating carries very little moisture. Leave it open overnight in rain and that property is gone, so the electrodes go back for rebaking within the manufacturer’s limits, or into the bin.
Candidates sometimes treat this as cosmetic, or try to fix it with a torch at the joint. Neither works. The free question on electrodes left open beside a tank shows how the scenario hides its answer in one line. Moisture becomes hydrogen in the arc, and the result is porosity or delayed cracking that can appear after the examination is finished. API RP 577 is the reference for welding processes, inspection and metallurgy on the effectivity sheet.
Where do candidates lose marks on these terms?
First, putting a fact on the wrong record. Second, reading the welder’s qualification as permission for any weld. A WPQ coupon was welded to one qualified WPS, and the production weld has to fall within what it covers.
Third, spending study time on excluded material. Dissimilar metal joints, overlay and hard-facing, consumable inserts and heat treatment requirements are all outside the review. The March 2027 effectivity sheet lists ASME BPVC Section IX in its 2025 Edition, welding only, plus API 650 in its 14th Edition and API 653 with Addenda 1 through 4.
Fourth, forgetting that the exam splits closed-book and open-book items. If a welding term question is closed-book, you cannot look anything up, so the definitions above need to be cold.
What should you do next?
Take any weld package you can find, a real one from work or a sample, and label every line WPS, PQR or WPQ before you read it for sense. Say out loud which link would fail.
The API 653 product page holds the exam facts, the full bundle marks items closed-book or open-book as the exam does, and the free quiz is a quick sample. The guides hub lists the rest. For the scope of this domain, read what the welding domain tests, then the common mistakes.
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