Valve Material Selection Guide Matching Body and Trim to Your Service Conditions

A valve is only as reliable as the materials it is made from. Two valves with identical dimensions and pressure classes can perform very differently once temperature, corrosion and fluid chemistry enter the picture. Selecting body and trim materials is therefore one of the most consequential decisions in any valve specification.

Body Materials: The Common Choices

Carbon steel (cast WCB, forged A105) is the industry default for oil, gas, steam and non-corrosive process services from −29°C to roughly 425°C. It offers excellent strength at low cost and is the standard body material for pipeline ball valves, gate valves and check valves. For low ambient temperatures, common in upstream and cryogenic-adjacent services, low-temperature carbon steels such as LCB/LCC or forged LF2 maintain impact toughness where A105/WCB would become brittle.

Stainless steels (cast CF8/CF8M, forged F304/F316) add chromium-nickel corrosion resistance for chemical, food-grade, marine and water treatment services, and handle both cryogenic and elevated temperatures. CF8M/316 is the usual pick where chlorides are present. For more aggressive media, seawater, sour gas, acids, duplex stainless, Monel and other nickel alloys come into play, though at significantly higher cost.

For waterworks and low-pressure services, ductile iron and cast iron bodies with resilient (EPDM) seats offer economical, long-lived performance in gate, butterfly and check valves, a different world from high-pressure steel valves, governed by AWWA rather than API standards.

Cast vs Forged Construction

Below about DN50 (2″), forged bodies (A105, F304, F316, LF2) are generally preferred: forging produces a denser, more uniform grain structure with no risk of casting porosity, which is why compact Class 800-1500 forged steel ball, gate and globe valves are standard in high-pressure small-bore piping. At larger sizes, casting becomes the practical and economical route, with quality assured through radiography and pressure testing.

Trim: Where the Real Work Happens

Trim, the ball or disc, stem, and seats, sees the highest velocities and wear. Stainless trim (316) in a carbon steel body is the classic economical combination. Seat material sets the temperature and tightness envelope: PTFE and RPTFE give bubble-tight shutoff to about 200°C; PEEK and Devlon extend pressure and temperature range; metal-seated valves handle abrasive slurries, high temperatures and fire-safe requirements where soft seats fail. Stem material must resist both corrosion and galling, 17-4PH and 316 are common choices.

Don’t Forget the Standards

Sour service (H2S) triggers NACE MR0175 / ISO 15156 material controls on hardness and composition. Fire-safe applications call for API 607 or API 6FA certified designs. Oxygen service requires special cleaning and copper-free alloys. When in doubt, state the full service conditions, fluid, concentration, pressure, temperature range and any trace contaminants, and let the material specification follow from them.

Get It Right First Time

Purple Valves supplies valves in carbon steel, low-temperature carbon steel, stainless and exotic alloys, in both cast and forged construction, with trim and seat options matched to your service. Send us your conditions and we will recommend the right combination, contact our team or explore the full product range.