Welding to AS/NZS 5131 and AS/NZS 1554

The framework: AS/NZS 5131 sits on top of AS/NZS 1554 and ISO 3834

AS/NZS 5131 does not replace the welding standards; it calls them up and adds controls linked to construction category. Clause 7.1.2 requires welding to comply with the relevant Part of AS/NZS 1554: Part 1 for general structures, Part 2 for stud welding, Part 4 for quenched and tempered steels, Part 5 for structures under high fatigue loading, and Part 7 for sheet steel. Clause 7.1.1 links the welding quality system to AS/NZS ISO 3834, recommending Part 4 for CC1, Part 3 for CC2, and Part 2 (comprehensive requirements) for CC3 and CC4. That is why an ISO 3834-2 certificate is one of the first documents an assessor asks a CC3 fabricator for.

Before welding starts, Clause 7.1.3 expects the construction specification and shop drawings to state, for every weld, its category, size, type, extent, required NDE and, if it differs, its construction category. Missing information should be raised as a request for information, not assumed – see specification and documentation.

Weld categories GP, SP and FP

AS/NZS 1554.1 defines two weld categories: GP (general purpose), for statically loaded welds with lower stress, and SP (structural purpose), for welds carrying higher design stress or dynamic loading where tighter imperfection limits apply. Where fatigue loading is severe, the designer can specify category FP under AS/NZS 1554.5 (or AS/NZS 1554.4 for quenched and tempered steels), which brings additional workmanship and inspection requirements (Clause 7.6.3). Under Table 7.4, CC1 is limited to GP, CC2 uses GP and SP, and CC3 and CC4 may involve GP, SP and FP. The designer – not the fabricator – nominates the category, and Clause 7.6.3 also expects the specification to state any extra execution measures assumed in the fatigue design.

Welding plan, procedures and personnel

Clause 7.2 recommends a welding plan as part of production planning, especially where later welds or parts will hide earlier welds, where lamellar tearing is a risk, for modifications to existing structures and for large complex fabrications. When the specification requires it, the plan covers WPS references, preheat and interpass, distortion control, sequence and stop–start locations, restraints, consumable handling, weld categories, weld identification and the cross reference to the ITP.

All production welding uses qualified procedures with a WPS complying with the relevant AS/NZS 1554 Part (Clause 7.4.1). Impact-tested procedures are tested at the lowest of the design service temperature, the specified test temperature or the steel standard's impact temperature, and weld-through primers are qualified at maximum film thickness.

Clause 7.4.3 requires welding coordination in all categories, by people with real knowledge of the processes, equipment and materials they supervise. Unless the specification says otherwise, the welding coordinator acts as examiner for welder qualification, and all welder test records must be available to the welding inspector.

Preparation and execution: what is checked on the shop floor

• Joint preparation (7.5.1): matches the qualified procedure test, within AS/NZS 1554 fit-up limits, clean and dry; shop primer stays on fusion faces only if the procedure was qualified with it.
• Consumables (7.5.2): stored and conditioned per AS/NZS 1554; hydrogen-controlled electrodes and fluxes go into an oven or quiver at 105 °C or more once unpacked; damaged consumables are discarded.
• Environment (7.5.3): gas-shielded welding needs wind below 10 km/h unless shielded or qualified; below 0 °C metal temperature, preheat and qualification rules apply.
• Preheat (7.5.5): determined from AS/NZS 1554, measured to AS ISO 13916, and applied to tack welds and temporary attachments too.
• Temporary attachments (7.5.6): made to a WPS, never on beam tension flanges, removed and the area ground and checked by magnetic particle examination.
• Tack welds (7.5.7): from CC2 upwards, made to a qualified procedure; cracked tacks removed.
• Butt welds (7.5.9): full throat at ends, run-on/run-off tabs where specified; at CC3 and CC4 permanent backing must be made continuous by full penetration welds; back gouging to a U-groove of at least 5 mm root radius.
• Finishing (7.5.15): arc strikes ground and checked by MT, spatter removed from CC2 upwards, slag removed; welds to be coated also meet Clause 9.8.

Changing weld locations or adding welds not shown on the drawings needs prior approval (Clause 7.5.4). Post-weld heat treatment, where specified, follows AS 4458; studs follow AS/NZS 1554.2. New Zealand adds seismic rules for continuity stiffeners, heat input and backing (Clauses 7.5.16–7.5.17).

Acceptance criteria and repairs

Clause 7.6.1 sets AS/NZS 1554 acceptance levels as the default, for the weld category nominated. An imperfection beyond those limits is a defect (Clause 13.6.2.5). It may be left only if a fracture mechanics or similar assessment, such as BS 7910, shows it is harmless and both principal and fabricator accept the method. Repairs use a qualified procedure, and repaired welds are re-examined to the original extent and method.

Inspection of welding under Clause 13.6

At CC3 and CC4 an inspection and test plan must address the full welding chain – from welding plan, WPS and welder qualifications through material and consumable identity, fit-up, parameters, preheat, tacking and back gouging to visual examination, NDE and acceptance (Clause 13.6.1.2). The ITP names who inspects, at which stage, which welds and by what method and extent. Every inspection is recorded with inspector, item, weld, date, criteria and result (Clause 13.6.1.4).

Visual examination is done before other NDE, to AS/NZS ISO 17637, and includes checking that every specified weld is present (Clause 13.6.2.3). Other NDE follows its method standard – AS 2062 (PT), AS 1171 (MT), AS 2207 (UT), AS 2177 (RT) – and waits for the minimum hold time of Table 13.6.2.1, which increases with weld size, heat input and steel type. Clause 13.6.2.2 recommends heavier sampling at the start of each new WPS, a minimum of about 1 m of weld per WPS, and stepping up inspection whenever defects appear.

Percentages are of weld length, and UT is generally unsuitable below about 10 mm thickness. Visual inspectors must be qualified as the AS/NZS 1554 Part requires; other NDE is carried out by AS ISO 9712 Level 2 personnel, or Level 1 under Level 2 supervision (Clause 13.6.1.3). See inspection and testing for the wider ITP.

For an offshore fabricator, the practical test is whether the records exist in English and link each weld to its WPS, welder, inspector and NDE report. Refer to the current edition of AS/NZS 5131 and AS/NZS 1554 for the full requirements.