A Welding Procedure Specification (WPS) is the technical document that defines how a particular weld joint is to be produced. The parameters it contains — process, material group, thickness range, welding position, filler metal, shielding gas, preheat and interpass temperature — form the framework to which the welder must adhere during production.
A WPS is mandatory in every production carried out under EN ISO 3834-2 and EN 1090 EXC2/3/4. Welding with an unapproved WPS can invalidate the structure's certification and CE marking.
Mandatory Basis of a WPS
The WPS requirement originates from multiple standards:
- EN ISO 3834-2 — Under comprehensive quality requirements, an approved WPS is mandatory.
- EN 1090-2 — A WPS is required for every welding process in execution classes EXC2 and above.
- EN 13445 — No welding may be performed on pressure vessels without a WPS + WPQR pair.
- PED 2014/68/EU — Welding procedure approval is mandatory for pressure equipment Category II and above.
A WPS is therefore not merely a rule; it is the technical foundation that proves the reliability of the structure.
What Does a WPS Contain?
| Section | Content |
|---|---|
| General Information | WPS number, revision, WPQR reference, preparing engineer |
| Base Metal | Material standard, steel group (ISO/TR 15608), thickness range |
| Welding Process | Process code (e.g. 135 MAG, 141 TIG), single/multi-pass, welding position |
| Filler Metal | Standard, classification, diameter, diffusible hydrogen class (H5 etc.) |
| Shielding Gas | Composition (Ar/CO₂ %), flow rate (l/min) |
| Electrical Parameters | Current (A), voltage (V), polarity, travel speed (cm/min), heat input (kJ/mm) |
| Thermal Conditions | Preheat temperature (°C), max. interpass temperature (°C), PWHT |
| Joint Preparation | Joint type, groove angle, root gap, root face |
Relationship with WPQR
A WPS must be based on a WPQR (Welding Procedure Qualification Record), an experimentally validated document. The sequence is:
- pWPS (preliminary WPS) is prepared — an engineer's draft based on technical knowledge.
- Qualification weld is made — with destructive test specimens.
- Destructive tests are performed — tensile, bend, hardness, Charpy, macro.
- WPQR is prepared — signed by an independent approving body (NB or accredited lab).
- WPS is approved referencing the WPQR and used in production.
Important: The WPS qualification range is derived from the test conditions in the WPQR. For example, a WPQR made on 12 mm may cover a range of 6–24 mm; however, it does not cover 25 mm.
ArmaWeld WPS Portfolio
ArmaWeld maintains a broad library of approved WPS documents under EN ISO 15614-1 (steel) and EN ISO 15614-2 (aluminium). This library covers the following material groups: structural steels S235–S960QL and Strenx 700/900/960/1100, pressure vessel steels P265GH/P355NH, austenitic stainless steels 304L/316L, HARDOX 400/450/500 wear-resistant steels, and aluminium alloys EN AW-5754/6082. At the start of every new project, the welding engineer verifies WPS applicability; if the scope is exceeded, a new pWPS and WPQR process is initiated.
Review Our WPS Portfolio
Share your project's material and thickness range; we will respond within 48 hours with the applicable approved WPS.
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