WPQR vs WPS: What's the Difference?

The short answer

A WPS (welding procedure specification) is the instruction: how to make the weld. A WPQR (welding procedure qualification record, called a PQR in AS/NZS and AWS usage) is the evidence: the record of the test that proved the instruction produces sound welds.

The WPS is what the welder follows. The WPQR is what you show the inspector when they ask how you know it works.

What goes in a WPS

The WPS is written per joint type and material group, and covers the variables a welder must follow:

• process or combination of processes
• base material specification and thickness range
• joint design and preparation, including root gap and land
• filler metal classification and size
• current, voltage, polarity and travel speed ranges
• preheat and interpass temperature
• number of passes and whether back gouging is required
• cleaning between passes and post-weld treatment

A WPS that does not state ranges is not much use — a welder needs to know what they are allowed to vary and what they are not.

What goes in a WPQR

The WPQR records the test that qualified that WPS:

• the WPS being qualified, and the test piece it was welded to
• welder and witness details, date and location
• the essential variables as tested — process, material, thickness, position, filler
• the test piece preparation and welding conditions actually used
• results of the destructive tests: tensile, bend, macro, impact or hardness as applicable
• the range of qualification the test supports: thickness range, positions, material groups

That last item is the part people overlook. The WPQR is what tells you how far the procedure can be stretched — a test on 10 mm plate qualifies a thickness range around it, not any thickness you like.

How they fit together

The sequence is always the same:

1. Draft the WPS with the variables you intend to use in production.
2. Weld a test piece strictly to that draft.
3. Destructively test the test piece to the standard.
4. Record the results on a WPQR.
5. If the tests pass, the WPS becomes a qualified procedure and can be issued for production.

If production then needs a thicker section, a different position or a different filler, that is a change to an essential variable — it needs either a new qualification test or a check against the range of qualification already recorded.

PQR, WPQR, WPS — why the confusion

PQR is the term used in AS/NZS 1554.1 and AWS D1.1. WPQR is the ISO/EN term (welding procedure qualification record). They describe the same thing: the documented proof behind a procedure. Australian projects commonly say PQR; European-linked clients and some QA systems say WPQR. Nobody is wrong.

Note also that AS/NZS 1554.1 allows prequalified WPS for common joint and material combinations — a standard procedure that does not need its own qualification test. If a project is using prequalified procedures, the documentation set looks different and the WPQR may not exist at all.

What an auditor asks for

• WPS for each joint type on the job, matching what is actually being welded
• the WPQR (or prequalified procedure reference) supporting each WPS
• welder qualification certificates current for the process and positions in use
• a drawing or weld map tying each weld to the procedure that covers it
• records showing preheat, consumables and inspection were carried out as specified

Missing WPQRs are the most common reason a fabrication package fails a client audit — the welds pass, the paperwork does not.