Category
Pressure Vessels & Reactors
Subcategory
Specialty
Applicable standards
5
Issuing bodies
4
Description
Boiler that recovers heat from gas turbine exhaust or process flue gas to generate steam.
Applicable Standards (5)
ASME — 2 standards
ASME BPVC Sec I
Rules for Construction of Power Boilers
Power boilers, electric boilers, miniature boilers and HRSGs.
Key requirements (8)
- Power boiler construction (steam generator) — section governs design, materials, fabrication.
- Maximum allowable working pressure (MAWP) calculated per Section I formulas (PG-27 for tubes, PG-29 for shells).
- Joint efficiency E: 1.0 (full RT), 0.85 (spot), 0.70 (no RT) for longitudinal seams.
- Hydrostatic test: 1.5 × MAWP held minimum 30 minutes.
- Mandatory PWHT and impact testing thresholds — stricter than VIII.
- Watertube boiler MAWP often 100–200+ barg for utility; firetube to ~30 barg.
- Material: SA-516, SA-285, SA-106, SA-335 (P11/P22/P91), etc.
- Quality system / authorized inspection mandatory.
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.
NFPA — 1 standard
NFPA 85
Boiler and Combustion Systems Hazards Code
Combustion safeguards (BMS) for fuel-fired boilers and HRSGs.
EN/CEN — 1 standard
EN 12952 (series)
Water-tube boilers and auxiliary installations
Multi-part standard for water-tube boilers in Europe.
Central Boilers Board (Govt. of India) — 1 standard
IBR 1950
Indian Boiler Regulations
Mandatory statutory regulation in India for boilers and steam piping >1.0 m³ volume or as defined by the IBR. Covers design, materials, fabrication, inspection, certification.
Key requirements (7)
- Indian Boiler Regulations — statutory in India for any boiler > 25 L water capacity & > 1 kg/cm² g.
- Approval/inspection by State Boiler Inspectorate (Chief Inspector of Boilers).
- Materials: IBR-approved certified by IBR-approved test house only.
- Hydrotest: 1.5 × design pressure after manufacture and at every annual inspection.
- Annual inspection mandatory; certificate (Form VI) renewed yearly.
- Welder qualification under IBR; approval valid for 2 years.
- Boiler Manufacturer's Code (BMC) registration required.
Note: Statutory — applicable in addition to design codes for boilers and IBR-regulated steam piping in India.