Overview
ISO 4987:2020 - Steel and iron castings - Liquid penetrant testing - specifies a penetrant testing method tailored to the steel and iron foundry industry. It complements the general principles in ISO 3452-1 and provides foundry-specific requirements for performing, interpreting and reporting liquid penetrant (LP) inspections on castings. The standard defines acceptance criteria, severity levels, operator qualifications, surface preparation and test conditions to ensure consistent non-destructive testing (NDT) of cast components.
Key topics and technical requirements
- Scope: Method for liquid penetrant testing of steel and iron castings (third edition, 2020).
- Normative references: ISO 3452-1 (general penetrant testing), ISO 3059 (viewing conditions), ISO 9712 (NDT personnel qualification), ISO 4990 (steel castings delivery requirements).
- Ordering information: Purchaser/manufacturer agreements should specify test area, operator qualification, sampling frequency, manufacturing stage for testing, required surface finish, discontinuity type and severity level.
- Testing procedure: Conduct testing in accordance with ISO 3452-1; viewing unaided or up to 3× magnification under ISO 3059 lighting conditions.
- Operator qualification: Personnel shall be qualified per ISO 9712 (or equivalent) for both testing and interpretation.
- Surface preparation: Surfaces must be clean and free of oil, grease, moulding or coating residues. Cleaning methods that can seal or close discontinuities are prohibited. Annex A provides recommended surface finishes.
- Indication classification:
- Non-linear indications (SP): length L < 3 × width W. Alignments (<2 mm apart and ≥3 indications) treated as a single SP.
- Linear indications (LP): length L ≥ 3 × width W. Individual and total lengths are assessed within a 105 × 148 mm frame.
- Severity levels and acceptance: Tables 1 and 2 define severity levels for SP and LP indications, including smallest considered indication, maximum individual length and total length allowances. LP criteria vary by section thickness type (t ≤16 mm, 16 < t ≤50 mm, t >50 mm).
- Supporting material: Annexes B–D provide reference figures and a model test report; retesting, classification and post-examination cleaning procedures are covered.
Practical applications and users
- Who uses it: Foundry quality managers, NDT technicians and supervisors, purchasing/specification engineers, inspectors, and end‑users of steel and iron castings.
- Applications:
- Incoming inspection of cast parts
- Production process control and final acceptance testing
- Supply‑chain specification and contract acceptance criteria
- Fracture-relevant screening using section-thickness based LP criteria
- Value: Ensures reproducible, industry‑specific acceptance criteria and reporting for reliable detection of surface-breaking defects in castings.
Related standards
- ISO 3452-1 - Penetrant testing: general principles
- ISO 3059 - Viewing conditions for penetrant/magnetic particle testing
- ISO 9712 - Qualification and certification of NDT personnel
- ISO 4990 - General technical delivery requirements for steel castings
Keywords: ISO 4987:2020, liquid penetrant testing, steel and iron castings, NDT, penetrant indications, severity levels, surface preparation, ISO 3452-1, ISO 9712.