Sour service
Exposure to hydrogen sulphide in oil and gas production at levels where cracking of susceptible materials becomes possible. ISO 15156-1 sets the conditions that define it and the requirements for materials selected to operate in it.
Sour service is a materials problem before it is a coating problem. The mechanism is environmental cracking of the metal itself — a coating does not qualify a material that the environment can crack.
The boundary is defined by partial pressure and pH rather than by a single concentration, which is why a service that is sour by one operator convention may not be by the standard’s.
Sources and references
- StandardISO 15156-1:2020 — Materials for use in H2S-containing environments in oil and gas production — Part 1International Organization for Standardization · accessed August 29, 2026
Where this is covered in depth
- NACE MR0175 vs MR0103: Material RequirementsUnderstand the critical differences between NACE MR0175 (ISO 15156) and NACE MR0103 for specifying materials in sour gas (H2S) environments.
- Galvanic corrosion in mixed-metal assembliesWhy the small part usually fails first, how the area ratio decides the severity, and why coating the wrong component makes the problem worse.