Piping Class Quick Reference
Every piping class side by side — ASME class, body material, design pressure and temperature, corrosion allowance and fluid service. The one-page comparison for picking the right class and reading a piping material specification.
What is a piping class and how do you read one?
A piping class (or piping material specification) fixes the body material, pressure rating, corrosion allowance and acceptable service for every component in a line — so a valve, flange and fitting all match. Classes step up from general carbon-steel service (A-series, Class 150-600) to stainless (B-series), chrome-moly for high-temperature steam (C-series), NACE-compliant sour service (D-series) and cryogenic (E-series). The table below compares every class at a glance; open any class for its full valve specification list.
| Class | ASME Class | Body Material | Design P | Design T | Corr. All. | Fluid Service |
|---|---|---|---|---|---|---|
| A1A | ASME Class 150 | Carbon Steel ASTM A216 WCB | 16 bar (232 psi) | Up to 200°C (392°F) | 3mm | General Service - Water, Air, Steam up to 16 bar |
| A2A | ASME Class 300 | Carbon Steel ASTM A216 WCB | 50 bar (725 psi) | Up to 350°C (662°F) | 3mm | Medium Pressure - Process, Steam, Hydrocarbons to 50 bar |
| A3A | ASME Class 600 | Carbon Steel ASTM A216 WCB | 100 bar (1450 psi) | Up to 400°C (752°F) | 3mm | High Pressure - Refinery, HP Steam, Oil & Gas to 100 bar |
| B1A | ASME Class 150 | Stainless Steel ASTM A351 CF8M (SS 316) | 19.6 bar (285 psi) | Up to 300°C (572°F) | Nil (SS service) | Stainless Steel - Chemical, Corrosive, Pharmaceutical Service |
| B2A | ASME Class 300 | Stainless Steel CF8M / A182 F316L | 51.1 bar (740 psi) | Up to 400°C (752°F) | Nil | Stainless Steel Medium Pressure - Corrosive Process to 51 bar |
| C1A | ASME Class 150 | 1¼Cr-½Mo (ASTM A217 WC6) or 2¼Cr-1Mo (A217 WC9) | 19.6 bar (285 psi) at ambient; derated per P-T tables above 400°C | Up to 565°C (1050°F) | 3mm | Alloy Steel - High Temperature Steam and HP Service |
| D1A | ASME Class 150 | Carbon Steel WCB / ASTM A216 with NACE MR0175 hardness control | 16 bar (232 psi) | Up to 200°C (392°F) | 3mm + NACE hardness limit | Sour Service - H₂S Containing Hydrocarbons, NACE MR0175 |
| E1A | ASME Class 150 (Cryogenic) | Austenitic SS ASTM A351 CF8M / A182 F316L | Up to 40 bar | -196°C to +65°C | Nil | Cryogenic - LNG, Liquid Nitrogen, LOX Service to -196°C |
| A4A | ASME Class 900 | Carbon Steel ASTM A216 WCB / A105N Forged | 148 bar (2149 psi) | Up to 400°C (752°F) | 3mm | Very High Pressure - HP Gas Injection, HP Wellhead, Sour Gas to 148 bar |
| A5A | ASME Class 1500 | Carbon Steel ASTM A216 WCB / A105N Forged | 247 bar (3584 psi) | Up to 400°C (752°F) | 3mm | Ultra-High Pressure - HP Wellhead, Gas Transmission, Subsea to 247 bar |
| A6A | ASME Class 2500 | Carbon Steel ASTM A216 WCB / A182 F22 Forged (2¼Cr-1Mo) | 412 bar (5975 psi) | Up to 400°C (752°F) | 3mm | Extreme High Pressure - Ultra-HP Wellhead, HP Instrument & Test Systems to 412 bar |
| B3A | ASME Class 600 | Stainless Steel ASTM A351 CF8M (Cast SS316) / A182 F316 Forged | 99.3 bar (1440 psi) at 38°C (100°F) | -29°C to +540°C (-20°F to +1004°F) | 0mm (stainless, no corrosion allowance) | High-Pressure Stainless - Corrosive Process, Sour Hydrocarbons with SS316 Body |
| D2A | ASME Class 600 | Carbon Steel ASTM A352 LCC (Low Temperature CS) with NACE MR0175/ISO 15156 Compliance | 99.3 bar (1440 psi) at 38°C (100°F) | -46°C to +425°C (-51°F to +797°F) | 3mm | Sour / H₂S Service - NACE MR0175 Compliant Carbon Steel, Class 600 |
| E2A | ASME Class 300 | Carbon Steel ASTM A352 LCC (Extended Bonnet, Cryogenic Tested) / A351 CF8M SS316 | 51.1 bar (741 psi) at 38°C (100°F) | -101°C to +120°C (-150°F to +248°F) | 0mm (cryogenic, non-corrosive - dry service) | Cryogenic Service - LNG / LOX / LIN, -46°C to -101°C, Class 300 |
| F1A | ASME Class 150 | Duplex Stainless Steel ASTM A890 Grade 4A / A182 F51 (Duplex 2205, UNS S31803/S32205) | 19.6 bar (284 psi) at 38°C (100°F) | -29°C to +315°C (-20°F to +599°F) | 0mm (duplex stainless, no corrosion allowance) | Seawater / Brine Service - Duplex 2205 Body, Class 150, PREN ≥35 |
Open any class for its full valve specification — gate, globe, check, ball, butterfly and strainer with end connection, body, trim and seat materials.
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Open the full specification for each class in the piping class library.