Reference
Welding and coatings QA guides
Direct answers on welding and coatings quality documentation: WPS, PQR and WQR, AS/NZS 1554 weld categories, qualification ranges, NDT extents, heat input and preheat, coating inspection records, and MDR handover packs.
Each guide opens with a direct answer, lists the numbers that matter, and cites the standards it relies on. They are written by the team building ForgeQM, which digitises the AS/NZS 1554 series as hard checks on welding and coatings QA records.
WPS, PQR and WQR: what each record proves and the order they are written
A PQR (Procedure Qualification Record) is the evidence: it records the parameters actually used on a test weld and the mechanical test results. A WPS (Welding Procedure Specification) is the instruction: it converts that evidence into ranges a welder may work within on production. A WQR (Welder Qualification Record, also called WPQ) is about the person: it proves a named welder produced an acceptable weld to a qualified procedure. The order is always preliminary WPS, then test weld, then PQR, then WPS, then WQR.
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How welding qualification ranges are worked out from a test weld
A qualification test weld qualifies a range, not just the tested value. Under AS/NZS 1554.1 a butt weld procedure test qualifies material from 0.5 to 2.0 times the thickness of the thinner test plate (Table 4.11(A) item (o)), and above 36 mm no upper limit applies at all (Clause 4.1.2(k)). Welder qualification is a separate calculation with its own position ranges from Table 4.12.2(A), and the standard states explicitly that the positional limits of the procedure do not apply to the welder. Changing an essential variable outside its band invalidates the qualification and requires a new test.
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AS/NZS 1554 weld categories: what SP, GP and FP actually change
SP (structural purpose) and GP (general purpose) are the two weld categories in AS/NZS 1554.1 Clause 1.6. The choice is structural before it is procedural: AS 4100 assigns a capacity reduction factor of 0.8 to an SP weld and 0.6 to a GP weld, so specifying GP gives up 25 per cent of the weld capacity for the same weld size. SP is selected where a weld is stressed above 50 per cent of the relevant maximum permissible stress or is subject to dynamic loading; GP covers welds below that threshold and non-structural applications. SP also carries tighter acceptance limits and heavier inspection. FP (fatigue purpose) is a separate category in AS/NZS 1554.5. The designer selects the category and nominates it on the drawings.
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How much NDT a weld actually needs, and where the extent comes from
Under AS/NZS 1554.1 only visual scanning is applied to 100 per cent of welds. Everything else is a sample: Table 7.4 suggests visual examination of 5 to 25 per cent for GP welds and 10 to 50 per cent for SP, with radiography or ultrasonics at nil for GP and 0 to 10 per cent for SP, and volumetric examination of SP butt welds only applies where the principal requires it and specifies it on the drawings. For pressure equipment the extent is tabulated directly against construction class in AS 4037, running from no volumetric requirement for Class 2b and Class 3 up to 100 per cent for Class 1, 1h and 2ha. The actual contracted extent is a matter to be resolved between principal and fabricator before work starts.
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Heat input, carbon equivalent and preheat: the formulas and how they connect
Arc energy is volts times amps divided by travel speed. Heat input is arc energy multiplied by a process thermal efficiency factor k, which is 0.8 for MMAW, GMAW and FCAW, 0.6 for GTAW and PAW, and 1.0 for SAW and electroslag. In kJ/mm with travel speed in mm/min the formula is Q = (V x A x 60) / (1000 x S) x k. Carbon equivalent measures how hard the steel is to weld, with the IIW formula CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15. AS/NZS 1554.1 Clause 5.3.4 combines the carbon equivalent band, the combined thickness of the joint and the arc energy to read a preheat temperature off a chart.
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What a coating inspection report has to record, and why dew point decides the day
A coating inspection report has to record four things to be defensible: the environmental conditions at the time of application (ambient temperature, surface temperature, relative humidity and dew point), the surface preparation grade achieved, dry film thickness readings against the specified minimum, and any holiday or pinhole testing. Dew point is the one that most often invalidates the work, because applying coating to a surface at or near the dew point traps moisture under the film. The common specification rule is that surface temperature must sit at least 3 degrees C above dew point.
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MDR and ITP: what goes in a handover pack and how to build it as you go
An Inspection and Test Plan (ITP) is the forward looking document: it lists every inspection and test activity for a job, who does it, what standard it is judged against, and where the hold and witness points sit. A Manufacturing Data Record (MDR), also called a data book or turnover pack, is the backward looking evidence: it compiles the completed records proving each ITP activity was carried out and accepted. The MDR should map one to one onto the ITP, and the reason handover is painful on most jobs is that the MDR is assembled at the end from records that were never linked to the plan.
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