Overview
EN ISO 23277:2015 - Non-destructive testing of welds - Penetrant testing - Acceptance levels - specifies acceptance criteria for indications from surface‑breaking imperfections in metallic welds detected by penetrant testing (PT). Primarily intended for use during manufacture inspection, the standard can also be applied to appropriate in‑service inspections. Acceptance levels are defined based on detection capabilities achievable when using techniques in the ISO 3452 series and the recommended parameters in Annex A.
Key topics and requirements
- Scope of inspection area: The test width includes the weld metal plus 10 mm of adjacent parent metal on each side.
- Acceptance levels (numeric limits):
- Linear indications (length l): Level 1: l ≤ 2 mm; Level 2: l ≤ 4 mm; Level 3: l ≤ 8 mm.
- Non-linear indications (major axis d): Level 1: d ≤ 4 mm; Level 2: d ≤ 6 mm; Level 3: d ≤ 8 mm.
- Levels 2 and 3 may be suffixed “X” to require linear indications to be evaluated to Level 1.
- Evaluation rules:
- Assess the size of the penetrant indication (not presumed defect size).
- Indications aligned and separated by less than the smaller indication length are treated as a single continuous indication.
- Initial and final evaluations follow ISO 3452‑1, with final sizing after a designated minimum development time and before degeneration of the indication.
- Testing parameters affecting detection:
- Sensitivity of penetrant materials (per ISO 3452‑2) - higher sensitivity for small imperfections.
- Surface condition - smooth/clean surfaces give better detectability; roughness increases background.
- Process and technique - selection of penetrant system and removal method (e.g., avoid swab cleaning on rough surfaces when detecting small flaws).
- Remediation: Where permitted, local grinding may remove unacceptable imperfections; re‑testing with the same PT system is required.
- Limitations: Acceptance levels for grouped indications are not covered.
Practical applications and users
- Used by NDT technicians, welding inspectors, quality engineers, fabricators and manufacturers for weld quality acceptance during production.
- Applicable to inspections in industries such as pressure vessels, piping, structural steel, and offshore fabrication where surface‑breaking weld defects are a concern.
- Useful for establishing acceptance criteria, linking PT results to welding quality requirements, and for compliance with contractual specifications and codes.
Related standards
Keywords: EN ISO 23277:2015, penetrant testing, NDT, weld inspection, acceptance levels, ISO 3452, surface condition, penetrant sensitivity, welding quality.
