Category
Pressure Vessels & Reactors
Subcategory
Pressure Vessel
Applicable standards
12
Issuing bodies
5
Description
General process pressure vessel (≥15 psig) per ASME VIII Div 1 — most common worldwide.
Applicable Standards (12)
API — 4 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 572
Inspection Practices for Pressure Vessels
Companion to API 510 — practical inspection methods.
Key requirements (8)
- Inspection practices for pressure vessels (companion to API 510).
- External inspection minimum: every 5 years.
- Internal inspection minimum: every 10 years (or one-half remaining corrosion allowance life).
- On-stream UT inspection acceptable in lieu of internal in many cases.
- Damage mechanisms reference: API 571 (HIC, SOHIC, polythionic SCC, CUI, HTHA).
- TML (Thickness Measurement Location) selection on injection points, dead legs, mixing zones.
- RBI (API 580/581) may extend interval based on risk assessment.
- WFMT, PAUT, AUBT for high-priority weld inspection.
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.
API 582
Welding Guidelines for the Chemical, Oil, and Gas Industries
Supplementary welding requirements (PWHT, hardness, impact, NDE) beyond ASME IX.
Key requirements (7)
- Supplementary welding requirements for chemical/oil/gas industries — beyond ASME IX.
- Mandatory PWHT thresholds tighter than ASME VIII.
- Hardness limits: 200 HB (CS), 235 HB (1.25Cr-0.5Mo / 2.25Cr-1Mo) for sour service typical.
- Charpy impact requirements at MDMT for all weldments where production weld is impact-tested.
- PMI (positive material identification) required on alloy components.
- Hydrogen-induced cracking (HIC) prevention: low-hydrogen consumables, preheat, controlled diffusible H ≤ 8 mL/100g.
- Heat input control for impact-toughness-controlled materials.
ASME — 4 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 BPVC Sec II
Materials (Parts A, B, C, D)
Material specifications (mostly identical to ASTM with SA prefix), filler metals, properties and allowable stresses.
ASME BPVC Sec IX
Welding, Brazing and Fusing Qualifications
Welding/brazing procedure and welder/operator qualification.
Key requirements (8)
- Welding and brazing qualifications.
- WPS (Welding Procedure Spec) supported by PQR (Procedure Qualification Record).
- PQR essential variables include: P-number, F-number, A-number, thickness range, position, preheat, PWHT, impact.
- Welder/operator qualification: bend tests OR radiography per QW-302.
- Coupon thickness qualifies a range: Table QW-451 (e.g., 25 mm coupon qualifies 5–50 mm).
- Position qualification: 6G qualifies all positions for pipe.
- Performance qualification expires if 6 months without welding (re-qualify).
- Notch toughness essentials when impact required by construction code.
ASME BPVC Sec V
Nondestructive Examination
NDE methods (RT, UT, MT, PT, ET, VT) referenced by Section VIII, B31.3, etc.
Key requirements (7)
- NDE methods: RT (radiography), UT (ultrasonic), MT (magnetic particle), PT (liquid penetrant), VT (visual), ET (eddy current), AE (acoustic emission), LT (leak).
- RT: density 1.8–4.0 (film), pixel density for digital.
- UT thickness: pulse-echo, accuracy typically ±0.1 mm.
- PAUT (phased array UT): increasing replacement of RT for thick welds.
- MT: residual or continuous magnetization, prods or yokes.
- PT: dwell time 5–60 minutes, developer dwell 7–30 min.
- Personnel certification: Level I/II/III per ASNT SNT-TC-1A or ISO 9712.
ASTM — 2 standards
ASTM A516 / A516M
Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature Service
Most-used carbon steel plate for pressure vessel shells (Gr 60, 65, 70).
ASTM A240 / A240M
Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels
304/304L/316/316L/321/duplex stainless plate for pressure vessels.
WRC — 1 standard
WRC Bulletin 107 / 537
Local Stresses in Spherical and Cylindrical Shells Due to External Loadings
Pressure vessel nozzle local stress analysis.
BIS — 1 standard
IS 2825 (legacy)
Code for Unfired Pressure Vessels
Legacy Indian pressure vessel code; many existing plants still reference it.
Key requirements (7)
- Indian Code for Unfired Pressure Vessels — generally aligned with ASME VIII Div 1.
- Three classes (1, 2, 3) corresponding to severity of service.
- Joint efficiency 1.0 (full RT), 0.85 (spot), 0.7 (no RT).
- Hydrotest: 1.3 × design pressure × (allowable at test/allowable at design).
- Material allowables drawn from Indian + ASME-equivalent grades.
- Used in conjunction with SMPV(U) Rules for statutory approval in India.
- Increasingly being superseded in industry by ASME VIII direct adoption.