Valve Body Materials: Carbon Steel, Stainless Steel, and Alloy Steels

ted wang
Jun 4
2 min read

How to Select Valve Body Material

Valve body material selection is determined by the process fluid chemistry, operating temperature, operating pressure, and regulatory requirements. The material must resist corrosion, maintain mechanical strength at service temperature, and be weldable or machinable for manufacture and repair. ASME B16.34 and ASTM material standards govern acceptable body materials for pressure-retaining components.

Carbon Steel Valve Bodies

ASTM A216 WCB: most common carbon steel casting for moderate temperature service (up to 425°C)
ASTM A105: carbon steel forgings for flanges and fittings up to 425°C
Low-temperature carbon steel LCB (A352): impact tested for service down to -46°C
Subject to corrosion in wet CO2, H2S, and acid service: not suitable for aggressive chemical environments
Economical choice for hydrocarbon, steam, and water services without corrosive chemistry

Stainless Steel Valve Bodies

Austenitic stainless steels (304, 316, 316L) are widely used for corrosive service including acids, chlorides, and food-grade applications. ASTM A351 CF8M (316 equivalent casting) and A182 F316 (forging) are standard grades for chemical and process service. For severe chloride service, super duplex (A890 Grade 6A) or super austenitic alloys are required to resist pitting corrosion.

Alloy Steel and Chrome-Moly Bodies

C0.5Mo (F1): low-alloy for moderate hydrogen service
1.25Cr-0.5Mo (F11): good creep resistance for high-temperature steam service
2.25Cr-1Mo (F22): widely used in hydrogen and high-temperature hydrocarbon service
5Cr-0.5Mo (F5): improved oxidation resistance for hot oil and high-sulfur service
9Cr-1Mo (F91): advanced creep strength for ultra-supercritical steam power plants

Material Identification and Traceability

All valve body materials must be traceable to certified material test reports (CMTRs) meeting EN 10204 Type 3.1 or 3.2. Positive material identification (PMI) using X-ray fluorescence (XRF) or optical emission spectrometry (OES) verifies alloy composition in the field. Material traceability is required for process safety management and integrity management programs, particularly for pressure equipment in critical service.