1. Scope
This procedure covers radiographic examination of carbon-steel and low-alloy-steel castings used in ASME pressure-bearing service — pump and valve bodies, ASME BPVC Section VIII Division 1 and Division 2 fittings, and ASME B16.34 valve bodies. Wall thickness range: 6 mm to 200 mm. Material classes: per ASTM A216, A217, A352, A487 typical for pressure-bearing applications.
2. References
- ASME BPVC Section V, Article 2 — Radiographic Examination
- ASME BPVC Section VIII Division 1, UG-77, UCS-57; Division 2, 7.5
- ASTM E446 — Reference Radiographs for Steel Castings up to 50 mm
- ASTM E186 — Reference Radiographs for Steel Castings 50–115 mm
- ASTM E280 — Reference Radiographs for Steel Castings 115–305 mm
- ASTM E1742 — Standard Practice for Radiographic Examination
- ASNT SNT-TC-1A / CP-189
3. Personnel Qualification
Radiographic examination by ASNT NDT Level II in RT; interpretation against reference radiographs by Level II with documented experience in casting interpretation; Level III sign-off for non-routine indications and on the procedure itself.
4. Equipment
- Source: Ir-192 for steel thickness 12 – 65 mm; Co-60 for 50 – 200 mm; X-ray (450 kVp – 1 MV) for surface-sensitive thin or moderate-thickness castings where focal-spot geometry favours sensitivity. Source activity per a calibrated exposure chart.
- Industrial radiographic film: Class I (ISO 11699 fine-grain) for primary examinations; lead intensifying screens 0.13/0.25 mm.
- Source-to-film distance per the geometric-unsharpness limit:
Ug = (F × t) / D ≤ 0.5 mm for t ≤ 50 mm
- ASTM E747 wire-type IQI in the production material — essential wire per ASME V Article 2 Table T-233.1 / T-233.2.
- Lead identification markers and shot identifiers.
- Variable-intensity film viewer; calibrated densitometer.
5. Surface Preparation
Casting surface free of moulding sand, loose oxide, and machining chips. Surface irregularities (riser stumps, parting-line flash) that would obscure a radiographic indication shall be ground or machined per the casting drawing's NDT note.
6. Technique
6.1 Single-Wall Single-Image (SWSI) — Preferred
Used for all castings where source-and-film access permits. Multiple shots arranged to cover the casting per a written shot map; minimum coverage: every wall thickness change and every prescribed inspection zone of the casting drawing.
6.2 IQI Placement
Source-side preferred per ASME V Article 2 §T-277. Film-side acceptable only where source-side is mechanically impossible; in that case, the radiograph must demonstrate that the additional film-side wire of the IQI table is visible.
7. Film Density and Sensitivity
7.1 Film Density
Through the area of interest: 1.8 to 4.0 (single-film viewing); 2.6 to 4.0 (composite viewing with two films). Maximum density variation across the area of interest: 30%.
7.2 IQI Sensitivity
Smallest essential wire visible per ASME V Article 2 Table T-276 — typical for castings:
- 6 – 19 mm thickness: 2T sensitivity equivalent to wire size #6
- 19 – 38 mm: wire #8
- 38 – 65 mm: wire #10
- 65 – 100 mm: wire #11
8. Interpretation
Castings interpreted against the appropriate ASTM Reference Radiograph (E446 / E186 / E280) for discontinuity type and severity level.
Discontinuity types per ASTM:
- A — Gas porosity (Severity 1 to 5)
- B — Sand and slag inclusions
- C — Shrinkage (sub-types CA / CB / CC / CD)
- D — Cracks (hot tears and cold cracks)
- E — Insufficient penetration / cold shut
- F — Inclusion-type defects
Each indication classified by type and severity level by comparison to the matching reference radiograph at the same thickness range.
9. Acceptance Criteria
Per the casting drawing / specification — typical ASME pressure-bearing service per Section VIII Division 1 UG-77 and UCS-57:
- Cracks (Type D, all sub-types): rejectable, regardless of severity.
- Hot tears (Type D-HT): rejectable.
- Type A porosity, Type B inclusions, Type C shrinkage: maximum severity level per the casting drawing — typical limits Severity 1 for Class A castings, Severity 2 for Class B, Severity 3 for Class C (where the casting class is called out in the design specification).
The casting drawing or material specification governs final acceptance; in the absence of a more specific limit, ASTM E446 Severity Level 3 applies for ASME Class B pressure-bearing service.
10. Repair and Re-Examination
Defects shall be removed by grinding or excavation per the casting Repair Welding Procedure (RWP). Repair-welded areas shall be re-examined by the same RT procedure plus MT or PT of the repair-weld surface per the controlling welding specification (typically ASME Section IX qualified).
11. Reporting
Per ASME V Article 2 §T-291 — examination report including: casting identifier, drawing and revision, material, equipment used, source identity and activity, SFD, exposure time, film type, IQI sensitivity confirmation, density readings, ASTM reference-radiograph match (type and severity) for every recordable indication, examiner name and certification, Level III sign-off, and disposition.
12. Safety
Compliance with 10 CFR Part 34. Restricted-area boundary at 2.0 mSv/hr; controlled-area boundary at 0.05 mSv/hr. Personnel dosimetry with audible alarm. Source-retraction verification by survey-meter reading after every shot.
This procedure is a published reference. Production use requires customer / AI approval against the current code edition and the casting class. Generate a casting-specific RT plan with the exact ASTM severity limit and shot map at the free AI Procedure Generator.