Category
Piping & Fittings
Subcategory
Power Piping
Applicable standards
6
Issuing bodies
3
Description
ASME B31.1 piping for power plants, steam, boiler external, district heating.
Applicable Standards (6)
ASME — 3 standards
ASME B31.1
Power Piping
Piping for steam, water, oil, gas and air services in electric power plants and central/district heating plants.
Key requirements (7)
- Power piping — boiler external piping, steam/water for power and district heating.
- Allowable stress: more conservative than B31.3 (additional safety factor for steam service).
- Hydrotest: 1.5 × design pressure (lower limit) — held minimum 10 min.
- Mandatory PWHT thresholds more strict than B31.3.
- Boiler external piping (BEP) under Section 1 of ASME BPVC.
- Non-boiler external piping (NBEP) under B31.1.
- Materials: stricter limits on materials below ductile-brittle transition.
ASME B16.5
Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24
Flange dimensions, ratings, materials and tolerances for NPS 1/2–24, Class 150–2500.
Key requirements (8)
- Pipe flanges & flanged fittings for NPS 1/2 to 24.
- Pressure classes: 150, 300, 400, 600, 900, 1500, 2500.
- Class 150 CS: 285 psig at 100 °F, 200 psig at 400 °F.
- Class 300 CS: 740 psig at 100 °F, 555 psig at 700 °F.
- Flange types: weld neck, slip-on, socket weld, threaded, lap joint, blind.
- Facing types: raised face (RF), ring-type joint (RTJ), flat face (FF).
- Bore matching: weld neck bore selected to match pipe schedule.
- Hydrotest: per pressure class temperature/pressure rating chart.
ASME B16.9
Factory-Made Wrought Buttwelding Fittings
Dimensions, tolerances, ratings, marking of butt-welding fittings (elbows, tees, reducers, caps).
Key requirements (7)
- Factory-made wrought butt-welding fittings — NPS 1/2 to 48.
- Pressure-temperature ratings match adjoining pipe (no separate rating).
- Standard fittings: 90° / 45° elbows, tees, reducers, caps, returns, lap-joint stub ends.
- Long radius elbow: 1.5×D centerline; short radius: 1.0×D.
- Wall thickness: matches pipe schedule of straight pipe of same NPS.
- Materials: carbon, alloy, stainless steel per ASTM A234/A403/A420.
- Hydrotest: at fitting manufacturer per pipe pressure rating.
ASTM — 2 standards
ASTM A106 / A106M
Seamless Carbon Steel Pipe for High-Temperature Service
Seamless carbon steel pipe (Grades A, B, C) for high-temperature service.
Key requirements (7)
- Seamless carbon steel pipe for high-temperature service.
- Grades A, B, C: Grade B most common (yield 35 ksi, UTS 60 ksi).
- Service temperatures up to ~427 °C (800 °F) per ASME B31.3 allowables.
- Composition: low S/P, controlled C, Mn for weldability and impact toughness.
- Used widely in refinery, petrochemical, power steam piping.
- Hydrotest: 1.5× allowable working pressure at mill.
- NPS range: 1/8 to 26.
ASTM A335 / A335M
Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service
Cr-Mo alloy steel pipe (P11, P22, P91, etc.) for elevated-temperature service.
Key requirements (7)
- Seamless ferritic alloy-steel pipe for high-temperature service.
- Grades: P5, P9, P11, P12, P22, P91, P92 (Cr-Mo content varies).
- P22 (2.25Cr-1Mo): widely used in refineries, power plants up to ~600 °C.
- P91 (9Cr-1Mo-V): high-temp creep resistance up to ~625 °C; mandatory PWHT.
- Heat treatment: normalized + tempered (or Q&T for some grades).
- Welding consumables matched to base metal (e.g., E9018-B3 for P22).
- Used for boiler tubes, superheaters, reheaters, hydrogen reformers.
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.