Category
Inspection & Process Safety
Subcategory
Testing
Applicable standards
4
Issuing bodies
2
Description
Pressure test (hydro / pneumatic) of vessels and piping for strength and leak.
Applicable Standards (4)
API — 2 standards
API 510
Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration
In-service inspection, repair, alteration and re-rating of pressure vessels.
Key requirements (8)
- Applies to in-service pressure vessels covered originally by ASME VIII or other recognized code.
- Inspection intervals: external ≤ 5 years, internal ≤ 10 years OR ½ remaining life — whichever is less.
- On-stream UT inspection can replace internal at user's choice if conditions permit.
- Authorized Inspector (AI) certification required for inspection signoff (API ICP).
- Repair/alteration must follow original construction code; reratings allowed via re-calculation + hydrotest waiver if conditions met.
- RBI per API 580/581 may justify extended intervals beyond default limits.
- Damage mechanisms reference: API 571.
- Fitness-For-Service per API 579 when defects exceed acceptance limits.
API 570
Piping Inspection Code
In-service inspection, rating, repair and alteration of process piping.
Key requirements (7)
- Applies to in-service process piping (B31.3 scope typical).
- Piping classified Class 1 (severe), 2 (most), 3 (less severe) by service.
- Thickness inspection intervals: Class 1 ≤ 5 yr, Class 2 ≤ 10 yr, Class 3 ≤ 10 yr (or ½ life).
- External inspection: Class 1/2 ≤ 5 yr, Class 3 ≤ 10 yr.
- CUI inspection mandatory in -12 °C to 175 °C range for insulated CS piping.
- Injection points and dead legs flagged as high-priority TMLs.
- Authorized Piping Inspector (API 570 ICP) certification required.
ASME — 2 standards
ASME BPVC Sec VIII Div 1
Rules for Construction of Pressure Vessels
Mandatory rules for design, fabrication, inspection, testing and certification of pressure vessels operating above 15 psig (~1 barg).
Key requirements (12)
- Applies to vessels with internal pressure > 15 psig (1.03 barg) up to ~3000 psi (Div 1 sweet spot).
- Joint efficiency E: 1.0 (full radiography), 0.85 (spot RT), 0.70 (no RT) for Type 1 butt joints.
- Shell thickness: t = P·R/(S·E – 0.6·P) for circumferential stress (UG-27).
- Head thickness: t = P·D/(2·S·E – 0.2·P) for 2:1 ellipsoidal heads (UG-32).
- Hydrostatic test pressure: 1.3 × MAWP × (S_test/S_design) — UG-99.
- Pneumatic test (when hydro impractical): 1.1 × MAWP — UG-100.
- Corrosion allowance is added to calculated thickness (not included in S formula).
- MDMT and impact testing per UCS-66 / Figure UCS-66; below the curve, Charpy V-notch impacts are required.
- PWHT thresholds per UCS-56 — generally required above 19 mm thickness for P-No. 1 carbon steels.
- Nozzle reinforcement: area replacement method (UG-37) within reinforcement zone.
- Maximum allowable stress S: from ASME II Part D, Table 1A/1B/3 — temperature dependent.
- Flanges per ASME VIII-1 Appendix 2 (or B16.5 for standard sizes).
Note: Most widely used pressure vessel code worldwide.
ASME B31.3
Process Piping
Piping in petroleum refineries; chemical, pharmaceutical, textile, paper, ore-processing plants and related processing facilities. Default process piping code worldwide.
Key requirements (10)
- Process piping — refining, chemical, pharmaceutical, semiconductor.
- Categories: Normal Fluid Service (default), Category D (low pressure < 150 psig & temp 38–186 °C), Category M (lethal), High Pressure, Severe Cyclic, High Purity.
- Allowable stress: lower of UTS/3, Yield/1.5, etc., from Table A-1.
- Wall thickness: t = P·D / (2·(S·E·W + P·Y)) where Y = 0.4 for ductile under 482 °C.
- Joint efficiency E: 1.0 (seamless), 0.85–0.95 (welded depending on RT).
- Hydrotest: 1.5 × design pressure × (S_test/S_design) — ≥ 10 minutes hold.
- Pneumatic test (when hydro impractical): 1.1 × design pressure with safety analysis.
- Examination: 5% RT for Normal service; 100% RT for Category M and Severe Cyclic.
- Flexibility analysis required when temperature differential > 28 °C and complex routing.
- Stress range allowable SA = f·(1.25·Sc + 0.25·Sh) with f = cyclic reduction factor.