Learn about international weld quality standards including ISO 5817 and AWS D1.1. Discover inspection methods, acceptance criteria, and documentation requirements.
Introduction
Weld quality standards ensure consistency and reliability. At Fulei Metal, we work to international standards for our clients across Europe, North America, Japan, and beyond.
Major Welding Standards
ISO 5817
European standard for weld quality. Three quality levels: B (stringent), C (intermediate), D (moderate). Specifies acceptance criteria for imperfections.
ISO 3834
Quality requirements for fusion welding. Defines comprehensive quality management for welding.
AWS D1.1
American standard for structural steel welding. Defines weld types, inspection, and acceptance. Common for North American clients.
AWS D1.6
American standard for stainless steel welding. Similar structure to D1.1.
EN 1090
European standard for execution of steel structures. Includes welding requirements. CE marking requires compliance.
Quality Levels (ISO 5817)
Level B (Stringent)
For critical applications. Minimal imperfections allowed. Requires high skill and control. Aerospace, pressure vessels, critical structures.
Level C (Intermediate)
Standard quality level. Moderate imperfections allowed. Most industrial applications. General fabrication.
Level D (Moderate)
For non-critical applications. More imperfections allowed. Architectural, non-structural. Cost-effective.
Inspection Methods
Visual Inspection (VT)
100% of welds visually inspected. Checks: bead shape, size, undercut, overlap, surface cracks, spatter, cleanliness. First-line quality check. Requires good lighting and access.
Dye Penetrant Testing (PT)
Detects surface-breaking defects. Apply penetrant, remove excess, apply developer. Defects show as colored indications. Good for non-magnetic materials (stainless, aluminum).
Magnetic Particle Testing (MT)
Detects surface and near-surface cracks. Magnetize the part, apply iron particles. Particles cluster at defects. Ferromagnetic materials only (carbon steel).
Radiographic Testing (RT)
X-rays or gamma rays penetrate the weld. Defects show as dark or light areas on film. Detects internal porosity, lack of fusion, cracks. Expensive but comprehensive.
Ultrasonic Testing (UT)
Sound waves reflect off defects. Detects internal flaws. Good for thick sections. Requires skilled operator.
Acceptance Criteria
Crack Tolerance
No cracks accepted at any quality level. All cracks must be repaired.
Porosity Tolerance
Level B: minimal porosity, small diameter. Level C: moderate porosity. Level D: more porosity allowed. Specific limits depend on thickness and weld type.
Undercut Tolerance
Level B: max 0.5 mm depth. Level C: max 0.5-1.0 mm. Level D: max 1.0-1.5 mm.
Excess Weld Metal
Limits on reinforcement height. Typically 1-3 mm depending on thickness.
Documentation
Welding Procedure Specification (WPS)
Documents: process, base metal, filler metal, parameters, positions, gas. Ensures consistent quality. Required for certified welding.
Procedure Qualification Record (PQR)
Records actual parameters used for test weld. Includes test results. Validates the WPS.
Welder Qualification
Certifies welder skill. Test weld evaluated per standard. Periodic renewal required. At Fulei Metal, our welders are qualified to international standards.
Inspection Reports
Document: inspection method, results, acceptance level, inspector, date. Traceability for quality records. Provided to clients as required.
Conclusion
Weld quality standards ensure consistent, reliable welds. At Fulei Metal, our adherence to international standards and comprehensive inspection ensures welds meet client requirements.
Which Standard Governs What, and What Each One Deliberately Does Not Cover
Buyers frequently ask for a welding standard without specifying what it should govern. There are three separate objects — the company, the procedure and the person — and each has its own document.
| Standard | It governs | It does not |
|---|---|---|
| ISO 3834 | Quality requirements for fusion welding at company level, with parts 2 to 4 covering comprehensive, standard and elementary requirements | It does not qualify a welder or approve a procedure by itself |
| ISO 15614-1 | Qualification of the welding procedure by test, producing a WPQR | It says nothing about the skill of the person running it |
| ISO 9606-1 and -2 | Qualification of the welder, for steel and for aluminium respectively | It does not approve the procedure the welder will use |
| ISO 14732 | Qualification of welding operators for mechanised and automatic welding, and of resistance weld setting operators | It does not cover manual welders |
| ISO 5817 | Quality levels for imperfections in arc-welded steel, levels B, C and D | It does not specify weld size or joint design; those are design decisions |
| ISO 10042 | The equivalent quality levels for arc-welded aluminium | It does not cover steel |
| AWS D1.1 / D1.2 / D1.6 | Structural welding codes for steel, aluminium and stainless respectively | They are not general-purpose quality systems for fabrication shops |
| ISO 17635 | Rules for non-destructive testing of fusion welds, including which method suits which imperfection | It does not set acceptance levels itself |
Two practical points follow from that table. First, ISO 5817 levels are a design choice, not a hierarchy of goodness: specifying level B across an entire assembly usually buys rework rather than performance, and the right approach is to specify B where fatigue or sealing matters and C elsewhere. Second, a welder qualification and a procedure qualification are different documents, and a package that contains one is not evidence of the other.
Frequently Asked Questions
What should a buyer actually ask for?
Three things, matched to risk: a procedure qualification relevant to the joint and material, a welder qualification with a scope that covers the positions and thicknesses involved, and an acceptance level stated per joint on the drawing. Anything more detailed than that usually costs money without reducing risk.
Does ISO 5817 level B mean a better weld?
It means a tighter acceptance limit on imperfections, which is only better where the imperfection actually affects performance. On a non-loaded cosmetic joint, level C with a specified finish is often the more sensible and more economical specification.
How long does a welder qualification last?
Under ISO 9606 the certificate runs for two years, but that validity depends on the employer confirming the welder is still working within the qualified scope every six months. Under the ASME and AWS systems, continuity of practice is the mechanism rather than a fixed expiry.
Questions about a specific part are usually faster to answer against the drawing — send it through the route below.
Practical next steps. Start with sheet metal welding service for the drawing review, read send the drawing for review for process context, and if you are choosing between routes, welder certification standards and welding inspection methods set out the alternatives side by side.