A welding procedure specification defines every parameter of a weld including the process, materials, joint preparation, preheat temperature, interpass limits, and welding consumables. Following the WPS ensures that every weld meets the design strength and quality requirements. Deviating from the WPS can produce welds that look acceptable but fail under load. This talk explains what a WPS contains and why every welder must follow it exactly.
Key Hazards
Weld failure under load from deviating from the specified welding parameters
Cracking or porosity from incorrect preheat temperature or interpass limits
Wrong consumable type used producing a weld with inadequate mechanical properties
Non-compliance rejected during inspection causing costly rework and programme delays
Control Measures
Obtain and read the approved WPS for every joint type before starting any welding on the project.
Confirm the welding process, consumable type, and wire diameter match the WPS specification exactly.
Measure and record preheat temperature using a calibrated contact thermometer before striking the arc.
Monitor interpass temperature and do not exceed the maximum stated in the WPS between passes.
Ensure the joint preparation matches the bevel angle, root gap, and root face specified in the WPS.
Use only the shielding gas type and flow rate specified in the WPS for the process in use.
Record all welding parameters on the weld log for every joint including heat input and travel speed.
Report any deviation from the WPS to the welding engineer immediately — do not continue without approval.
Ensure each WPS has been qualified by a procedure qualification record (PQR) before use on the project.
Remember
Obtain and read the approved WPS for every joint type before starting any welding work
Confirm consumable type, wire diameter, and shielding gas match the WPS specification exactly
Measure and record preheat temperature with a calibrated thermometer before striking the arc
Do not exceed the maximum interpass temperature stated in the WPS between weld passes
Report any deviation from the WPS to the welding engineer immediately without continuing
Record all welding parameters on the weld log for every joint for full quality traceability
Applicable Legislation: CDM Regulations 2015 · BS EN ISO 15614 (Welding Procedure Qualification) · BS EN 1090-2 (Execution of Steel Structures) · Health and Safety at Work etc. Act 1974