What material should a safety & relief 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

Safety & Relief Valves for Carbon Monoxide (CO) Service

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

Which safety & relief valves for Carbon Monoxide (CO)?

Safety Relief Valve - Mandatory overpressure protection - CO must vent to safe location (flare) Typical service window: 0.1–350 barg, Ambient to +900°C (blast furnace/reformer).

Recommended Configurations

Safety Relief Valve

Mandatory overpressure protection - CO must vent to safe location (flare)

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

Other valve types for Carbon Monoxide (CO)

Gate Valves for Carbon Monoxide (CO)Ball Valves for Carbon Monoxide (CO)Globe Valves for Carbon Monoxide (CO)Check Valves for Carbon Monoxide (CO)

Safety & Relief Valves for other services

Safety & Relief Valves for Ammonia (NH₃)Safety & Relief Valves for LNG / Cryogenic Natural Gas Safety & Relief Valves for High-Pressure Steam Safety & Relief Valves for LPG - Liquefied Petroleum Gas Safety & Relief Valves for Nitrogen (N₂)Safety & Relief Valves for Liquid Nitrogen (LN₂)Safety & Relief Valves for Argon (Ar)Safety & Relief Valves for Propylene / Propene (C₃H₆)

Reviewed by Process Engineering, Vajra Industrial SolutionsDiscipline: Process & Fluid Service EngineeringLast reviewed: 20 June 2026

Connected Engineering

Standards

ASME B16.34

Products

Safety / Relief Valves

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Relevant Products

Vajra Safety & Relief Valves

Engineering references

Carbon Monoxide (CO) service guideFull compatibility, standards & considerations Vajra Safety & Relief ValvesFull range, specs & standards Spec Check engineValidate this spec before the RFQ