🔍 Key Concepts

• Sulfide stress cracking (SSC) and how hydrogen sulfide (H₂S) weakens certain metals • The difference in behavior between high strength steel and low strength steel in corrosive, sour gas environments • Which materials are most commonly limited or specially treated for use in H₂S (sour service) according to industry practice

💭 Think About

• Think about which material’s strength level makes it more brittle and therefore more likely to crack when hydrogen embrittlement occurs. • Consider which of these materials (rubber, high strength steel, aluminum, low strength steel) is most often subject to strict controls or special selection for use in sour (H₂S) service pipelines and pressure vessels. • Ask yourself: when H₂S causes hydrogen to enter a metal, does a higher or lower steel strength usually mean a higher risk of stress cracking?

✅ Before You Answer

• Verify which type of steel (high strength vs low strength) is more susceptible to sulfide stress cracking and hydrogen embrittlement in standard materials engineering references. • Confirm that non‑metallic materials like rubber and certain metals like aluminum do not usually top the list for SSC risk in H₂S compared with susceptible steels. • Check industry guidance (e.g., NACE MR0175/ISO 15156) on which strength levels of steel require the most caution in H₂S environments.