The short answer: A coded welder is certified to BS EN ISO 9606 standards. Learn what coded welding means, how welders qualify, and why clients require coded welders for structural work
A coded welder is a welder who has passed a formal welding qualification test to a recognised standard, demonstrating that they can consistently produce welds that meet the required quality criteria for safety-critical applications.
The term “coded” refers to holding a weld procedure qualification — typically to BS EN ISO 9606 (the primary standard in the UK and Europe) or equivalent standards such as ASME Section IX. The qualification tests a welder's ability to produce an acceptable weld under defined conditions: specific process, material, thickness, position, and joint type.
A coded weld qualification certificate from a UKAS-accredited test centre confirms the welder has met the standard. Certificates are valid for a defined period (typically 2–3 years) and require periodic renewal.
Coded welding is required where weld failure could have serious consequences: pressure vessels, pipework operating under pressure, structural steelwork for buildings and bridges, lifting equipment, and similar safety-critical applications.
EngineeringUK’s annual report highlights that the UK faces a significant and growing shortfall in engineering and technical professionals — with welding and fabrication trades among those most affected as the existing workforce ages. The Welding Institute (TWI) has noted that demand for formally qualified coded welders continues to outpace supply in key sectors including energy, petrochemical, and infrastructure.
BS EN ISO 9606 is the European and British standard for qualification testing of welders. Part 1 covers fusion welding of steels; Part 2 covers aluminium and aluminium alloys. A welder qualified to BS EN ISO 9606 has been independently tested and their qualification is documented — meaning it can be verified by the client, inspector, or insurer.
A coded welder's qualification covers specific welding positions and material/thickness ranges. For pipe welding, the 6G position (pipe at 45°) is the most comprehensive qualification. Read more: Welding Types | What Is Welding?
Varlowe's welders hold Class 1 coded welding qualifications and are available for site work across the UK. We also offer mobile welding services.
For more information, visit our Coded Welding page or email us. Contact us
A coded welder is a welder who has passed a formal practical test to demonstrate they can produce welds that meet the requirements of a recognised standard — typically BS EN ISO 9606 in the UK and Europe. The test is independently assessed and produces a certificate specifying the exact range of materials, thicknesses, positions, and processes the welder is qualified to weld.
BS EN ISO 9606 is the internationally recognised standard for the qualification testing of welders. Part 1 covers fusion welding of steels; Part 2 covers aluminium and aluminium alloys. A qualification certificate details the exact scope covered — process, material group, filler type, joint type, dimensions, and welding positions.
For structural, pressure, or safety-critical welds, coded welders provide independently verified assurance that the person performing the weld has been tested to a defined standard. Major clients — including main contractors, utilities, and process industry operators — specify coded welding as a contractual requirement for pipework, structural steelwork, and pressure vessels.
Under BS EN ISO 9606, an initial qualification is valid for two years, provided the welder remains in continuous production welding on the relevant process and material. After two years, the employer must confirm the welder has been engaged in relevant work; after three years, a new qualification test is required.
Yes. Varlowe Industrial Services employs BS EN ISO 9606 coded welders qualified across multiple processes (MIG, TIG, MMA), materials, positions, and thickness ranges including the 6G pipe position. Their coded welding capability supports structural, pipework, and pressure applications for industrial clients across the Midlands and nationally.