What material should a ball valve for Carbon Monoxide (CO) be?

Carbon Steel (Excellent): Standard for most CO service. PWHT required for weld-end valves. SS 316L (Good): Acceptable for CO service; avoid where nickel content is a concern for Ni(CO)₄ formation.

Carbon Monoxide (CO) service

Service Selection

Ball Valves for Carbon Monoxide (CO) Service

Which ball valves configuration suits Carbon Monoxide (CO) (CO), in which material, to which standard — from real service data, with the pitfalls flagged.

Which ball valves for Carbon Monoxide (CO)?

Ball Valve (WCB, PTFE seat) - Isolation and block service for CO lines in methanol and Oxo plants Typical service window: 0.1–350 barg, Ambient to +900°C (blast furnace/reformer).

Recommended Configurations

Ball Valve (WCB, PTFE seat)

Isolation and block service for CO lines in methanol and Oxo plants

Body Material for Carbon Monoxide (CO)

Rated from real compatibility data - click any material for the full decision page.

Carbon SteelStandard for most CO service. PWHT required for weld-end valves.Excellent SS 316LAcceptable for CO service; avoid where nickel content is a concern for Ni(CO)₄ formation.Good Hastelloy C-276High nickel content - same Ni(CO)₄ risk as above. Verify with process chemist.Fair Nickel alloys (Inconel, Monel)Nickel carbonyl formation above 150°C - avoid in high-CO partial pressure service.Poor

Governing Standards for Carbon Monoxide (CO) Service

ASME B16.34 API 600API 941 (HTHA - for co-present H₂)ASME B31.3

What to Avoid in Carbon Monoxide (CO) Service

Nickel-base alloy valves in high CO partial pressure above 150°C
Non-PWHT welded valves in CO service

Service Considerations

CO gas detection system with 25 ppm alarm in all CO-containing areas - odourless, immediately lethal
Avoid nickel-base trim above 150°C in high-CO partial pressure - nickel carbonyl risk
All CO vents and drains must terminate at flare - CO must never be vented to atmosphere
PWHT mandatory for welded carbon steel valves in CO service