MEDIA GUIDE
Sour Service Valves (H₂S-Bearing)
A certification requirement, not an alloy upgrade.
Sour (H2S-bearing) hydrocarbons are a metallurgy-controlled duty: every wetted and bolting component must comply with NACE MR0175 / ISO 15156 (hardness control, H2S partial-pressure limits) — that is a certification requirement, not an alloy upgrade. State the H2S content and whether the service is wet in your inquiry.
Service flags: NACE / ISO 15156 service, flammable, toxic.
Materials at a glance
| Material | Rating | Up to |
|---|---|---|
| Carbon steel (ASTM A216 WCB) | Excellent | 300 °C |
| Stainless steel 304 (ASTM A351 CF8) | Excellent | 300 °C |
| Stainless steel 316 (ASTM A351 CF8M) | Excellent | 300 °C |
| Duplex 2205 (ASTM A995 Gr.4A) | Good | 300 °C |
Ratings: Excellent / Good / Conditional / Not recommended, from this site's boundary-and-medium data set. The manufacturer's data sheet for the specific product governs.
What drives the choice
- Every wetted and bolting component must comply with NACE MR0175 / ISO 15156 — hardness control, H₂S partial-pressure limits
- State the H₂S content and whether the service is wet in the enquiry
- Bolting moves to B7M/2HM rather than B7; solution-annealed and hardness-capped stainless
Where the boundaries sit
- The qualification follows the environment description — without H₂S partial pressure, pH, chloride and temperature there is nothing to qualify against
Related reading
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