What are Weld Production Tests?

A Weld Production Test

Weld Production Tests are weld tests performed at the manufacturing / fabrication site by the manufacturing contractor. All aspects of the product weldment are represented and the welding system is identically that applied for the production welding.

The production weld test samples are inspected to identify if the weld is readily performed in the practical welding sense, by visual examination and additionally by Non-Destructive Examination where necessary). Then the weld test piece(s) are sampled and tested (usually by Destructive Testing). Both readiness of performing a sound weld and the engineering performance of that weld are usually both determined in a production weld test.

What are the main differences between the Production Weld Test approach and the currently dominant ISO15614 weld qualification approach?

The ISO15614-family of Weld metallurgical qualification Standards grant a "range of qualification" of weld variables in relation to the conditions tested over which it is believed that the weld qualification will be valid (which is a problematic concept)

Production tests must always exactly relicate or so closely replicate the production weld that there is no difference between the production test weld and the production weld.

Therefore, there is no concept of a "range of qualification" associated with weld production tests and therefore no problems arising from the problematic assumptions underpinning the "range of qualification" concept.

Standards like Norsok M-601, "Welding and inspection of piping" introduce a primary reliance on weld production tests to qualify welds. Norsok M-601 has the interesting structure that it overlays ASME B31.3, a pragmatic North-American Standard (Code) for process pipe. ASME B31.3 has the "range of qualification" for weld variables but Norsok M-601 requires that these "Welding Procedure Specifications" are proven applicable for the exact welding conditions to be used in production, by a weld production test. Any ASME B31.3 weld qualification "inherited" into the work is in-effect a "secondary" weld qualification which suggests welding conditions which might be applicable - but requires the primary proof of a weld production test that the desired weld outcome is actually achieved.

(R. Smith, 06Oct2015)