Overview
ISO 17638:2016 - "Non‑destructive testing of welds - Magnetic particle testing" specifies accepted techniques for detecting surface imperfections in welds of ferromagnetic materials using magnetic particle testing (MPT). The standard covers inspection of welds and heat affected zones for most welding processes and joint configurations, describes variations that affect sensitivity (Annex A), and sets out procedural, safety and equipment considerations. ISO 17638:2016 does not set acceptance criteria for indications; those are found in ISO 23278 or product/application standards.
Key topics and technical requirements
- Scope and purpose: Detection of surface-breaking and near‑surface discontinuities in ferromagnetic welds using magnetic particles.
- Personnel: Inspection shall be performed by qualified NDT personnel (recommendation: ISO 9712 or equivalent).
- Safety: Precautions for toxic/volatile materials, electrical hazards, unfiltered UV and strong magnetic fields.
- Surface preparation: Surfaces should be dry and suitably cleaned without damaging the material or finish; wet-surface media permitted when specified.
- Magnetizing methods: Use of electromagnetic yokes, current-flow with prods, adjacent/threading conductors, coils; DC or permanent magnets only by agreement. Typical guidance on field direction, pole separation and overlap is provided to ensure full coverage.
- Field verification: Recommended tangential field for structural steels is about 2 kA/m to 6 kA/m (r.m.s.); verification methods include test pieces, Hall‑effect probes, current calculations or other established techniques.
- Detection media: Dry powders or magnetic inks/suspensions conforming to ISO 9934‑2; media performance must be verified against reference indications.
- Application techniques: Magnetize in two approximately perpendicular directions (±30°) for full orientation coverage; allow time for indications to form before removing the field.
- Quality assurance: Overall performance tests, avoidance and identification of false indications, recording of indications, demagnetization and test reporting requirements.
Practical applications & users
ISO 17638:2016 is used to develop and control magnetic particle weld inspection procedures across industries that fabricate, assemble or maintain ferromagnetic welded components. Typical users include:
- NDT inspectors and technicians
- Welding engineers and quality managers
- Fabrication shops, maintenance and inspection organizations
- Procurement and compliance teams specifying weld inspection requirements
The standard helps organizations implement repeatable, safe and verifiable magnetic particle testing for weld integrity, root‑cause investigation and in‑service inspection.
Related standards
Keywords: ISO 17638:2016, magnetic particle testing, MPT, non‑destructive testing of welds, ferromagnetic weld inspection, NDT weld inspection.