Category
Piping & Fittings
Subcategory
Process Piping
Applicable standards
13
Issuing bodies
5
Description
ASME B31.3 process piping for refineries, chemical plants, pharma, semiconductor.
Applicable Standards (13)
API — 2 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 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 — 6 standards
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.
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.
ASME B16.11
Forged Fittings, Socket-Welding and Threaded
Socket-weld and threaded forged fittings (Class 2000/3000/6000/9000).
Key requirements (6)
- Forged steel socket-welding and threaded fittings — NPS 1/8 to 4.
- Pressure classes: 2000, 3000, 6000, 9000 (threaded); 3000, 6000, 9000 (socket weld).
- Used in small-bore process piping (instrumentation, drains, vents).
- Materials: A105 (carbon), A182 (alloy/stainless).
- Threading per ASME B1.20.1 (NPT).
- Hydrotest: per fitting class rating.
ASME B36.10M
Welded and Seamless Wrought Steel Pipe
Standardized dimensions for carbon and low-alloy steel pipe (Sch 5 through XXS).
Key requirements (6)
- Welded and seamless wrought steel pipe — dimensions and weights.
- Pipe schedules: 5, 5S, 10, 10S, 20, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160, XS, XXS.
- Schedule 40 CS most common for general service.
- Outside diameter constant per NPS; wall thickness varies by schedule.
- NPS 14 and above: NPS = OD in inches; below NPS 14: NPS ≠ OD.
- Pipe length: random (16–22 ft) or double random (35+ ft) typical.
ASME B36.19M
Stainless Steel Pipe
Stainless steel pipe dimensions (5S, 10S, 40S, 80S).
Key requirements (6)
- Stainless steel pipe — dimensions and weights.
- Schedules: 5S, 10S, 40S, 80S (lighter wall than B36.10 carbon).
- Schedule 10S: typical for low-pressure stainless service.
- Schedule 40S: dimensions match Schedule 40 of B36.10 for some sizes.
- OD identical to B36.10 — flanges and fittings interchangeable.
- Materials: ASTM A312, A358, A409 typical.
ASTM — 3 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 A312 / A312M
Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes
Seamless and welded austenitic stainless steel pipe (TP304/304L, TP316/316L, etc.).
Key requirements (7)
- Seamless, welded, and heavily cold-worked austenitic stainless steel pipe.
- Grades: TP304, TP304L, TP316, TP316L, TP321, TP347, TP310 most common.
- Yield strength: TP304 = 30 ksi; TP304L = 25 ksi; TP316/TP316L similar.
- Service temperatures: cryogenic to ~815 °C depending on grade.
- Manufacturing: seamless (SMLS), welded (EFW/EFSW), heavily cold-worked (HCW).
- Pickled and passivated finish required.
- Hydrotest: 1.5× working pressure at mill.
ASTM A234 / A234M
Pipe Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
Carbon and alloy butt-welding fittings (WPB, WP11, WP22, WP91).
Key requirements (7)
- Pipe fittings of wrought carbon steel and alloy steel for moderate and high-temperature service.
- Grade WPB: most common — equivalent to A106 Grade B pipe.
- Grade WPC: heavier wall version.
- Alloy grades: WP1, WP11, WP22, WP91 (Cr-Mo for high temp).
- Heat treatment: normalized (or normalized + tempered).
- Charpy impact: required for some grades at low temp.
- Used for elbows, tees, reducers, caps in B31.3 / B31.1 piping.
ISO — 1 standard
ISO 15649
Petroleum and natural gas industries — Piping
ISO process piping design referencing ASME B31.3.
BIS — 1 standard
IS 1239 (Parts 1, 2)
Steel Tubes, Tubulars and Other Wrought Steel Fittings
Mild steel tubes (Light/Medium/Heavy class) and fittings — common in Indian utility piping.
Key requirements (7)
- Steel tubes, tubulars and other wrought steel fittings.
- Part 1: Tubes (Class A, B, C) — light, medium, heavy.
- Part 2: Fittings.
- Galvanized for water service common (Class B medium).
- Pressure ratings matched to Class and NPS.
- Used for water, gas, and general low-pressure service in India.
- Hydrotest: per class rating at mill.