EN ISO 15156-3:2020 PDF

Overview - EN ISO 15156-3:2020 (H2S, CRAs, SSC, SCC, GHSC)

EN ISO 15156-3:2020 (ISO 15156-3:2020) is the CEN-endorsed part of the ISO 15156 series that provides requirements and recommendations for the selection and qualification of cracking‑resistant CRAs (corrosion‑resistant alloys) and other alloys for use in H2S‑containing environments in oil and natural gas production and gas treatment plants. It addresses material cracking mechanisms (not mass loss corrosion) and is intended for equipment whose failure could affect health, safety or the environment.

Key topics and technical requirements

• Cracking mechanisms covered: sulfide stress cracking (SSC), stress corrosion cracking (SCC) and galvanically induced hydrogen stress cracking (GHSC).
• Scope limits: focuses only on cracking resistance; general or localized corrosion (mass loss) is excluded. Not necessarily suitable for refining or downstream equipment.
• Material qualification and selection: guidance on parent‑metal hardness, weldability and welding/post‑weld properties, and other fabrication effects on cracking resistance.
• Use of PREN: the document discusses PREN (pitting resistance equivalent number) as one factor in material evaluation.
• Design approach: applies to equipment designed with load‑controlled design methods; for strain‑based design see ISO 15156‑1:2020.
• Purchasing and traceability: specifies information to supply at purchase, marking, labelling and documentation requirements to ensure the selected CRA/alloy meets the intended service qualification.
• Normative annexes: include environmental materials selection tables and laboratory qualification procedures (e.g., Annex A and B), plus informative guidance on purchasing information and nominated test conditions.

Practical applications and users

• Who uses it: corrosion engineers, materials engineers, mechanical designers, procurement specialists, inspection and QA/QC teams, and regulatory/compliance personnel in upstream oil & gas and natural gas treatment sectors.
• Where it applies: selection and qualification of CRAs and high‑alloy materials for wellheads, tubing, piping, pressure vessels, seals and other components exposed to sour (H2S‑containing) production fluids where cracking risk is critical.
• Why it matters: helps avoid catastrophic cracking failures and costly asset loss by prescribing qualification routes, test methods and purchasing documentation to ensure materials will resist SSC, SCC and GHSC in defined sour environments.

Related standards

• ISO 15156 series (parts 1–3) - for broader guidance on materials in H2S environments.
• ISO 15156‑1:2020 - referenced for strain‑based design considerations.
• NACE test methods (e.g., TM0177, TM0284) - commonly used laboratory tests referenced for qualification.

Keywords: EN ISO 15156-3:2020, H2S, corrosion‑resistant alloys, CRAs, sulfide stress cracking, SSC, stress corrosion cracking, GHSC, oil and gas materials selection.