ISO 15156-2:2009 gives requirements and recommendations for the selection and qualification of carbon and low-alloy steels for service in equipment used in oil and natural gas production and natural gas treatment plants in H₂Scontaining environments, whose failure can pose a risk to the health and safety of the public and personnel or to the environment. ISO 15156-2:2009 can be applied to help to avoid costly corrosion damage to the equipment itself. It supplements, but does not replace, the materials requirements of the appropriate design codes, standards or regulations.

ISO 15156-2:2009 addresses the resistance of these steels to damage that can be caused by sulfide stresscracking (SSC) and the related phenomena of stressoriented hydrogeninduced cracking (SOHIC) and softzone cracking (SZC).

ISO 15156-2:2009 also addresses the resistance of these steels to hydrogeninduced cracking (HIC) and its possible development into stepwise cracking (SWC).

ISO 15156-2:2009 is concerned only with cracking. Loss of material by general (mass loss) or localized corrosion is not addressed.

Tables are included that give a non-exhaustive list of equipment to which ISO 15156-2:2009 is applicable, including permitted exclusions, lists of SSCresistant carbon and low alloy steels, and requirements for the use of cast irons.

ISO 15156-2:2009 applies to the qualification and selection of materials for equipment designed and constructed using conventional elastic design criteria, including designs utilizing plastic criteria (e.g. strainbased and limitstate designs).

ISO 15156-2:2009 is not necessarily suitable for application to equipment used in refining or downstream processes and equipment.