Piping Class Reference

Piping Class C1A Valve Specification

Piping Class C1A uses chrome-moly alloy steel (WC6/WC9) for high-temperature steam service above 425°C where carbon steel is no longer adequate for creep resistance. Found in main steam lines, superheat headers, and HRSGs (Heat Recovery Steam Generators) in power plants.

ASME Class

ASME Class 150

Design Pressure

19.6 bar (285 psi) at ambient; derated per P-T tables above 400°C

Design Temperature

Up to 565°C (1050°F)

Body Material

1¼Cr-½Mo (ASTM A217

Design Parameters — C1A

Fluid Service

Alloy Steel — High Temperature Steam and HP Service

Design Pressure

19.6 bar (285 psi) at ambient; derated per P-T tables above 400°C

Design Temperature

Up to 565°C (1050°F)

Corrosion Allowance

3mm

Body Material

1¼Cr-½Mo (ASTM A217 WC6) or 2¼Cr-1Mo (A217 WC9)

Industries

Power generation (main steam), Boiler superheater headers

Reference Only — Project-Specific Verification RequiredThis piping class specification is a general industry reference. Actual piping class definitions vary by project and company standard (owner specifications). Always verify material, rating, and end-connection requirements against your project's official piping class datasheet or PMS (Piping Material Specification). Vajra Industrial Solutions accepts no liability for specification decisions based on this reference.

Valve Schedule — Piping Class C1A

Valve Type	Rating	End Connection	Body Material	Trim	Seat/Sealing	Notes
Gate Valve	Class 150–600 (P-T derated)	RF or BW (ASME B16.25)	A217 WC6 / WC9	13Cr / Stellite-6	Stellite-6 HF	OS&Y, pressure-seal bonnet for Class 600+
Globe Valve	Class 300–600	RF or BW	A217 WC6 / WC9	Stellite-6	Stellite-6 HF	Y-pattern for HP steam throttling
Check Valve	Class 300–600	RF or BW	A217 WC6 / WC9	Stellite-6 HF	Stellite-6 HF	Tilting disc for HP steam — low pressure drop

Typical Industries — C1A

Power generation (main steam)Boiler superheater headersHRSGRefinery HP steam

Standard Certifications for C1A Valves

ASME B16.34API 6DAPI 607 (Fire Safe)API 608EN 10204 3.1ISO 9001:2015IBR (Indian Boiler)API 598 Testing

Shop Valves for Piping Class C1A

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Related Piping Classes

A2A

ASME Class 300

Medium Pressure — Process, Steam, Hydrocarbons to 50 bar

A3A

ASME Class 600

High Pressure — Refinery, HP Steam, Oil & Gas to 100 bar

All Piping Classes

A1A — ASME Class 150 A2A — ASME Class 300 A3A — ASME Class 600 B1A — ASME Class 150 B2A — ASME Class 300 D1A — ASME Class 150 E1A — ASME Class 150 (Cryogenic)

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