Carbon steel
- ASTM A106 Gr B / API 5L X42-X65 — workhorse for hydrocarbons and utilities
- Low-temp limit typically −29 °C without impact testing
- A333 Gr 6 for impact-tested low-temperature service to ~ −46 °C
Stainless steel
- 304/304L — general corrosion service, not for chlorides at temperature
- 316/316L — chloride and mild acid resistance, default SS in oil & gas
- Watch for sensitisation above ~425 °C and chloride SCC above ~60 °C
Higher alloys
- Duplex 2205 / Super duplex 2507 — chloride SCC resistance, seawater
- Inconel 625 / 825 — sour, high chloride, high temperature
- Hastelloy C-276 — aggressive acids and oxidising/reducing mixes
Sour service
For wet H2S service, materials, hardness, and PWHT must comply with NACE MR0175 / ISO 15156. Confirm with the project sour-service philosophy before specifying.
Key references
- · NACE MR0175 / ISO 15156
- · API RP 571
Use of this content
This page is a decision-support and training reference. It is not a substitute for the governing code, the project specification, or the judgement of a responsible engineer. Always validate against the current edition of the applicable standard before use on live engineering work.