ISO 15156-3:2020

Overview

ISO 15156-3:2020 - Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production - Part 3 - provides requirements and recommendations for selection and qualification of cracking‑resistant CRAs (corrosion‑resistant alloys) and other alloys for use in equipment exposed to wet H2S. The standard focuses on avoiding failures caused by cracking mechanisms (not general corrosion) that can endanger personnel, the public or the environment. It supplements design codes and applies primarily to equipment designed using load‑controlled design methods.

Key Topics and Requirements

• Cracking mechanisms covered: sulfide stress cracking (SSC), stress corrosion cracking (SCC), and galvanically induced hydrogen stress cracking (GHSC).
• Scope limitation: the document addresses cracking only - it does not cover general (mass loss) or localized corrosion. It is not necessarily suitable for refining/downstream equipment.
• Material selection and qualification:
  • Requirements and recommendations for CRAs and other alloys used in H2S-containing environments.
  • Evaluation of material properties including hardness, weldability and cracking-resistance of welds, and effects of fabrication processes.
  • Use of PREN (pitting resistance equivalent number) as a relevant material consideration.
• Environmental guidance and tables: normative Annex A provides environmental material selection tables and guidance on their use; Annex B covers laboratory qualification testing.
• Purchasing and traceability: specifies information to be supplied at purchase, marking, labelling, and documentation requirements to ensure correct material application.
• Design approach: applicable to load‑controlled design methods; strain‑based designs should reference ISO 15156‑1:2020, Clause 5.

Applications and Who Uses It

• Intended for material engineers, corrosion engineers, procurement specialists, and design teams in the oil and gas production and natural gas treatment sectors.
• Typical applications include wellheads, flowlines, gathering systems, and field processing equipment that may encounter H2S-containing production fluids (see standard’s equipment applicability and exclusions).
• Practical value:
  • Helps prevent catastrophic failures from SSC/SCC/GHSC.
  • Guides qualification of CRAs and high‑performance alloys for sour service.
  • Reduces costly rework, downtime, and environmental risk from material cracking.

Related Standards

• ISO 15156‑1:2020 - General principles for selection of cracking‑resistant materials (see strain-based design).
• ISO 15156‑2:2020 - Cracking‑resistant carbon and low alloy steels.
• NACE MR0175 / NACE TM0177 - Historical and test-method references used in sour‑service material guidance.

Keywords: ISO 15156-3:2020, H2S-containing environments, corrosion-resistant alloys, CRAs, sulfide stress cracking, stress corrosion cracking, material selection, oil and gas production.