ISO 17636-1

Applies to: Film-based radiographic testing (X-ray and gamma-ray) of fusion-welded joints in carbon steel, stainless steel, and non-ferrous metals; Techniques A (basic sensitivity) and B (improved sensitivity); standard for piping fabrication inspections under ISO- or EN-referenced codes.

Does NOT cover: Digital radiographic methods (CR, DDA) — use ISO 17636-2; in-service radiography for fitness-for-service (refer to API 579-1/ASME FFS-1); radiation protection and safety.

• Image Quality Indicators (IQI) per ISO 19232 (wire or step/hole type)
• Source-to-film distance (SFD) to limit geometric unsharpness (Ug)
• Film optical density range: 2.0–4.0 for Technique B
• Film system class C4 minimum for Technique B
• Sensitivity verification: IQI wire or hole visibility confirmed
• Test records: radiograph identification, geometry diagram, exposure conditions

ISO 17636-1 standardizes film radiographic technique for weld inspection, defining the parameters that determine detection capability: source-to-film distance, film class, density range, and IQI type. Technique B (improved sensitivity with tighter Ug limits and higher-class film) is typically specified for ASME B31.3 high-pressure process piping and Category I pressure vessels.

Engineering note: Film RT (ISO 17636-1) is increasingly being supplemented or replaced by digital RT (ISO 17636-2) due to digital's advantages in workflow, archiving, and post-processing. However, film RT remains the contractual baseline in many legacy project specifications and regulatory frameworks. When transitioning to digital RT, confirm the client's ITP explicitly accepts ISO 17636-2 as an alternative.