Category
Inspection & Process Safety
Subcategory
In-Service Inspection
Applicable standards
6
Issuing bodies
2
Description
In-service inspection, repair, alteration and rerating of process piping.
Applicable Standards (6)
API — 5 standards
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.
API 574
Inspection Practices for Piping System Components
Inspection practices for piping components — companion to API 570.
API 578
Guidelines for a Material Verification Program (MVP) for New and Existing Assets
Positive Material Identification (PMI) program requirements.
API 571
Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Catalog of ~70 damage mechanisms (corrosion, cracking, metallurgical, mechanical, environmental).
Key requirements (5)
- Catalog of >70 damage mechanisms in refining and petrochemical service.
- For each mechanism: description, materials affected, factors, appearance, prevention/mitigation.
- Examples: high-temp H2S corrosion, naphthenic acid corrosion, polythionic acid SCC, CUI, MIC.
- Hydrogen damage: HTHA per Nelson curves (now revised post-Tesoro 2010 incident).
- Used as input to RBI (API 580/581) and inspection planning.
API 579-1 / ASME FFS-1
Fitness-for-Service
Quantitative engineering assessment of equipment with flaws (corrosion, cracks, dents, blisters, fire damage, creep, etc.) for continued service.
Key requirements (7)
- Fitness-For-Service standard, jointly with ASME (FFS-1).
- Three assessment levels: 1 (screening), 2 (detailed analytical), 3 (advanced FEA / fracture mechanics).
- Part 4: General metal loss; Part 5: Local metal loss; Part 6: Pitting.
- Part 7: HIC and SOHIC; Part 8: Weld misalignment; Part 9: Crack-like flaws.
- Part 10: Creep; Part 11: Fire damage; Part 12: Dents and gouges; Part 13: Laminations.
- RSF (Remaining Strength Factor) method for general metal loss; RSF ≥ 0.90 typical screening.
- Companion to API 510, 570, 653 for repair-vs-replace decisions.
ASME — 1 standard
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.