**Part 1 — General (scope and definitions).
**Part 2 — Quality specifications and manufacturer certification.**
EN 15085-1 requires that welding manufacturers hold a certification audited by a notified body. Unlike ISO 3834, where self-declaration is possible for lower tiers, railway welding requires third-party surveillance. The manufacturer is classified as CL1 (highest), CL2, or CL3 depending on the weld categories they produce. CL1 requires a full quality system with an independent welding coordinator.
**Part 3 — Design specifications for welded joints.**
This is where EN 15085 differs most from general fabrication standards. The standard classifies welds into four categories (CP A to CP D) based on the consequences of failure. A CP A weld (safety-critical, e.g., bogie frame, wheel, axle connection) requires full volumetric NDT on every weld. No sampling. No percentage. 100% RT or UT. Design reviews must consider fatigue, weld geometry, and access for inspection at the design stage, not after fabrication.
From TRAC's analysis: "The classification system specifies requirements for different weld categories. The complexity of the weld, the size, and the materials used are taken into account."
**Part 4 — Manufacturing requirements.**
EN 15085-4 introduces specific production requirements that go beyond ISO 3834-2. These include:
- Mandatory pre-production weld tests for new joint geometries
- Weld sequencing plans for distortion control
- Welding at low temperatures (below 5°C) requires preheat even for non-alloy steels
- Limits on repair welding — repeated repairs on the same joint are restricted
**Part 5 — Inspection, testing, and documentation.**
The documentation requirement is explicit: welding procedures, welder qualifications, inspection records, and test results must be kept up to date and traceable for the service life of the vehicle. For CP A and CP B welds, this means records follow the vehicle through multiple overhaul cycles, potentially 30+ years.
**Field perspective.**
If you work in railway welding, the CL classification determines everything: weld category allowed, NDT scope, welder qualifications, and documentation depth. Moving from CL2 to CL1 is not just a paperwork upgrade. It requires a change in how joints are designed, how welders are assigned, and how inspection hold points are planned.
Source: TRAC Industrie, EN 15085 and Welding in the Railway Industry, February 2026.