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Key takeaways
- The WPS is the welding recipe; the PQR is the test record proving that recipe gives sound welds with the right properties.
- Welder qualification (WPQ) proves that an individual welder can make a sound weld with a process and position.
- Essential variables decide when a new procedure qualification is needed; P-numbers group base metals to reduce the number of tests.
The three documents
Welding procedure specification (WPS). The instructions for making a weld: process (SMAW, GTAW, GMAW, FCAW, SAW), base metal, filler metal, preheat, interpass temperature, heat input, positions, gas, and PWHT.
Procedure qualification record (PQR). The record of a test weld made following the WPS, and of the test results: tensile tests, bend tests, and where required impact tests and hardness surveys. A WPS must be supported by one or more PQRs.
Welder performance qualification (WPQ). The record that a specific welder made an acceptable test weld, checked by bend tests or radiography. It lists the processes, positions, thickness and diameter ranges the welder is qualified for.
How Section IX organises the variables
- P-numbers group base metals with similar weldability. Carbon steel is P-No. 1, so a procedure qualified on one P-No. 1 material covers others in that group.
- F-numbers group filler metals by usability, and A-numbers by weld metal chemistry.
- Essential variables are changes that affect mechanical properties and require requalification (for example a change of P-number or of PWHT condition).
- Supplementary essential variables apply when impact toughness is required (for example a significant increase in heat input).
- Non-essential variables can change by revising the WPS without a new test.
Keeping welders qualified
A welder’s qualification for a process stays valid as long as the welder uses that process at least once every six months, which is recorded in a continuity log. Production weld radiography results are also used to monitor welder performance, and many projects track a repair rate per welder.
Onshore
Onshore projects in North America and Asia mostly qualify procedures and welders to ASME Section IX.
Offshore
Offshore projects following NORSOK often use ISO 15614 for procedure qualification and ISO 9606 for welders, with NORSOK M-601 adding extra testing such as hardness and, for duplex, ferrite and corrosion tests.
Code reference
ASME BPVC Section IX Welding, brazing and fusing qualifications.
ISO 15614-1 Specification and qualification of welding procedures for metallic materials.
ISO 9606-1 Qualification testing of welders: steels.
What to take back to your desk
When you review a weld map, check that every weld has a WPS that covers its material, thickness and position, and that the welder’s qualification covers the same. Mismatches are common audit findings.
Educational content. Always design to your project specification.
