Sour service is a certification duty before it is a sizing duty. Once H2S is in the gas, NACE MR0175 / ISO 15156 governs what materials and hardness levels are acceptable — and that belongs on the face of the RFQ, not in a late technical review.
The selector carries sour service as an explicit flag: tick it and the report tells the manufacturer what to certify. The reference duty below is a wellhead-gathering isolation point.
Typical duties
| Wellhead and gathering isolation | Sour gas · 40–100 bar · ambient to 80 °C · DN50–300 |
|---|---|
| Process-plant sour lines | Sour gas/crude · 16–60 bar · ambient · DN50–200 |
| Metering and station piping | Sour gas · 40–70 bar · ambient · DN25–150 |
70 bar · 60 °C · DN200 on Sour Gas / Sour Crude (H2S-bearing, NACE service) (gas): Ball Valve (floating / trunnion-mounted) · body Carbon steel (ASTM A216 WCB) · Class 600.
bubble-tight quarter-turn isolation is the modern default for this duty
/* r11 P3-6 (user-approved): the duty-specific caution (e.g. class utilisation) belongs ON the page, not only in the unlocked report — the last boilerplate line stays report-only */Watch: Your duty uses 75% of the Class 600 rating at this temperature (70 bar of 93.2 bar) — inside the published rating, but with little room for pressure surges. Ask the manufacturer to confirm, or consider the next class up.
What to watch
- The NACE flag changes the report's certification requirements — it is the clearest example on this site of a checkbox that alters the specification, not the valve type.
- Body and trim are screened for the medium; the sour flag then constrains what the manufacturer must prove.
- If the duty is both sour and high-pressure, expect the class lookup to matter as much as the material.
Where this connects on this site
- Sour service as a medium — the compatibility picture
- Sour Service Valve Materials: What ISO 15156 / NACE MR0175 Actually Constrain
- API 6D Enters US Pipeline Law: What Federal Adoption of the 25th Edition Changes
- Ball valves — the gas-isolation default
Boundary rule: this page states single-point conclusions from the site's knowledge base — no supplier names, no matrices. The full 40-medium library lives in the selector.