Welder qualification, WPS and welding procedures in 3 seconds.

ISO 3834 has three levels of quality requirements for fusion welding of metallic materials. ISO 3834-2 defines comprehensive requirements and is mandatory for EXC3 and EXC4 structures under EN 1090-2. ISO 3834-3 defines standard requirements, applicable to EXC2. ISO 3834-4 defines elementary requirements for EXC1 structures. The choice of level depends on the execution class required by the client or project, the applicable standard (EN 1090, EN 13480, etc.) and the criticality of the welded assemblies. Certification bodies (TUV, Bureau Veritas, Lloyd's) audit compliance with the level agreed with the client.

Welder qualification under EN ISO 9606-1 (steels) is obtained by passing a welding test under the conditions defined by the essential variables: welding process (111 shielded metal arc, 131 MIG, 141 TIG, etc.), joint type (butt, fillet), welding position (PA flat, PB horizontal, PF vertical upward, PE overhead, etc.), material type (group according to CR ISO 15608), product type (plate or pipe), filler metal and thickness. The qualification obtained has a range of validity covering conditions similar to those of the test. Validity is 3 years if the company certifies semi-annual maintenance. The welding coordinator must record and monitor the validity of all qualifications.

The WPS (Welding Procedure Specification) is the document describing how to perform a weld: process, base and filler materials, edge preparation, position, electrical parameters (current, voltage, travel speed) and heat treatments. The WPQR (Welding Procedure Qualification Record) is the document recording the results of the test that validated that WPS: welded test piece, mechanical tests performed (tensile, bend, Charpy impact, macro, hardness) and the evaluation by the testing body. A WPS is only valid if a WPQR exists to support it. Both documents are systematically reviewed in ISO 3834 audits.

ISO 3834 requires NDT to be performed according to the inspection level defined in the applicable product standard and execution class. For steel structures under EN 1090-2, the main methods are: visual testing (VT — EN ISO 17637, always mandatory), liquid penetrant testing (PT — EN ISO 3452-1), magnetic particle testing (MT — EN ISO 17638), ultrasonic testing (UT — EN ISO 17640) and radiographic testing (RT — EN ISO 17636). The inspection percentage and acceptance criteria depend on the execution class (EXC1 to EXC4) and the joint category. NDT personnel issuing reports must hold Level 2 qualification under EN ISO 9712.

EXC (Execution Class) is the EN 1090-2 classification system for steel structures. It defines the manufacturing requirement level in four classes: EXC1 (simple structures, low consequence of failure), EXC2 (standard residential and industrial buildings), EXC3 (structures with high consequence of failure) and EXC4 (singular structures with life safety risk). The relationship with ISO 3834 is direct: EXC1 requires ISO 3834-4, EXC2 requires ISO 3834-3, EXC3 and EXC4 require ISO 3834-2. To obtain the CE marking for steel structures under EN 1090-1 it is necessary to demonstrate ISO 3834 conformity at the corresponding level, generally through third-party certification.

ISO 3834-2 (comprehensive requirements) demands exhaustive traceability throughout the welding process. Mandatory records include: identification of base materials used (material certificates 3.1 or 3.2 per EN 10204), WPS code applied to each joint, identification of the welder who performed each run and their valid qualification at that time, actual welding parameters (current, voltage, travel speed), preheat and interpass temperatures, results of NDT performed and their evaluation, and any repair made with its repair WPS. This level of documentation is examined in detail by certification bodies and is one of the areas where the most non-conformities are found in first-time certification audits.