Welding is fundamental to the construction and repair of mining equipment, from primary structural joints in excavator booms to repair welds on haul truck frames and structural columns in processing facilities. When welding is done incorrectly or left uninspected, the consequences can be catastrophic — weld failures account for a significant proportion of structural incidents in mining. This guide explains the key Australian standards governing welding quality, what a compliant welding program looks like, and how inspection and certification protect your operation.
Key Australian Welding Standards
AS/NZS 2980 (Qualification of welding procedures for the welding of steel) is the primary standard for welding procedure qualification in Australia. It requires that any welding procedure used on structural or pressure-containing components be formally qualified through a welding procedure specification (WPS) supported by a procedure qualification record (PQR).
AS/NZS 1554 is the series of standards covering structural steel welding in Australia. Part 1 covers welding of steel structures; Part 2 covers stud welding; Part 5 covers welding of steel structures subject to dynamic loading — the most relevant for mining equipment, which is subject to cyclic loading from working loads, travel, and ground-induced vibration.
For pressure equipment, AS/NZS 3992 (Pressure equipment — Welding and brazing qualification) applies. Where mining equipment includes pressure-containing components — hydraulic cylinders, pressure vessels, compressed-air systems — welds in these systems must comply with AS/NZS 3992.
Welding Procedure Specifications (WPS)
A Welding Procedure Specification is a documented set of welding parameters that, when followed by a qualified welder, will produce a weld of acceptable quality. A WPS defines the essential variables of the welding process: material specification, joint design, filler metal type, preheat and interpass temperature requirements, welding process and technique, and post-weld heat treatment if applicable.
The WPS must be qualified through testing. A test weld is made to the WPS parameters, and the resulting weld joint is tested mechanically (tensile, bend, impact) and by NDT. If the test results meet the specified acceptance criteria, the procedure is qualified and a PQR is issued. Only WPS-supported welding should be used for structural repairs on mining plant.
One of the most common welding compliance failures in mining repair operations is the absence of a formal WPS. A welder producing a repair weld "as they see fit" without a qualified procedure has no documented basis to claim that the weld quality is adequate for the application.
Welder Qualification
In addition to a qualified welding procedure, the welders performing structural work must themselves be qualified. Welder qualification under AS/NZS 2980 involves the welder completing a test weld within the WPS parameters, which is then tested by NDT and mechanical testing. A welder qualification is specific to the welding position, process, material group, and thickness range tested.
A welder who is qualified to weld flat (1G/1F) is not automatically qualified to weld overhead (4G/4F). Qualification test results should be documented in a Welder Performance Qualification Record (WPQR), and welders should hold a current qualification certificate for the work they are performing.
In field repair conditions — which are common in mining — qualification maintenance can lapse if welders move between projects or companies. A responsible operator verifies that welders hold current qualifications before allowing them to perform structural welds on safety-critical plant.
Inspection Hold Points for Welding Work
Welding inspection is most effective when it is built into the repair process as a series of hold points — defined stages at which the inspector must examine and approve the work before it progresses. A typical hold-point structure for a structural weld repair includes: pre-weld inspection (joint preparation, fit-up, and preheat compliance); in-process inspection (interpass temperature, technique, and run progression); and post-weld inspection (dimensional, visual, and NDT).
Visual inspection is always the first NDT method and should not be overlooked. Most weld discontinuities have a visual manifestation — undercut, overlap, surface cracks, craters, incomplete coverage — and catching these visually before deploying more sophisticated methods saves time and cost.
Post-Weld Inspection Methods and Acceptance Criteria
Post-weld inspection typically combines visual examination with at least one NDT method appropriate to the weld type and application. For fillet welds on structural connections, magnetic particle inspection (MT) is standard. For full-penetration welds in primary structure, UT or PAUT should be added. Acceptance criteria must be defined before inspection begins — typically referencing the relevant AS/NZS 1554 part or a project-specific acceptance standard.
Post-weld heat treatment (PWHT) may be required for certain material grades, joint thicknesses, or service conditions. If PWHT is required, it must be carried out before final NDT, and the temperature cycle must be recorded and verified against the WPS requirements. NDT performed after PWHT is the final check on weld quality before the component is returned to service.
Evidence base for procurement
Public sources · reviewed 19 Sep 2026These regulator and standards sources provide the public basis for the inspection context on this page. They describe requirements and application context; they do not claim that Mining Inspection Australia holds a qualification, accreditation or project history.
Standards Australia Store
Requirements for welding steel structures; confirm the applicable part, edition and project specification before relying on it.
Standards Australia Store
Qualification testing for welding operators and weld setters for mechanised and automatic welding of metallic materials.
Frequently asked questions
Do all weld repairs on mining equipment require a qualified WPS?
Any weld repair on a structural or safety-critical component should be backed by a qualified WPS. Minor non-structural welds (e.g., attaching a cable tray bracket) may not require the same formality, but for any weld in primary structure, a qualified procedure is both a regulatory expectation and good engineering practice.
What NDT is required after welding repairs on an excavator boom?
Post-weld NDT on an excavator boom weld repair should include 100% visual inspection followed by MT of all accessible weld surfaces to detect surface cracks. Full-penetration welds should also receive UT or PAUT examination. Acceptance criteria should be specified before inspection.
Can repairs be made in the field without a welding inspector present?
Field welds on safety-critical plant should not be accepted without some form of inspection. Where an independent welding inspector is not present, the repair organisation should at minimum document the WPS used, the welder's qualification, preheat compliance, and provide post-weld NDT results. The mine operator carries the duty to ensure repairs are fit for service.
What is the difference between a welding inspector and a welding engineer?
A welding inspector — typically a Certified Welding Inspector (CWI) or International Welding Inspector (IWI) — is qualified to examine, assess, and document weld quality against defined acceptance criteria. A welding engineer holds tertiary qualifications and can design weld joints, qualify procedures, and provide engineering judgement on fitness for service. Complex structural repairs often benefit from both.