This part of ISO15156 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 H 2S-containing environments, whose failure can pose a risk to the health and safety of the public and personnel or to the environment. It 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. This part of ISO15156 addresses the resistance of these steels to damage that can be caused by sulfide stress-cracking (SSC) and the related phenomena of stress-oriented hydrogen-induced cracking (SOHIC) and soft-zone cracking (SZC). This part of ISO15156 also addresses the resistance of these steels to hydrogen-induced cracking (HIC) and its possible development into stepwise cracking (SWC). This part of ISO15156 is concerned only with cracking. Loss of material by general (mass loss) or localized corrosion is not addressed. Table1 provides a non-exhaustive list of equipment to which this part of ISO15156 is applicable, including permitted exclusions. This part of ISO15156 applies to the qualification and selection of materials for equipment designed and constructed using load controlled design methods. For design utilizing strain-based design methods, see ISO15156‑1:2015 , Clause5. AnnexA lists SSC-resistant carbon and low alloy steels, and A.2.4 includes requirements for the use of cast irons. This part of ISO15156 is not necessarily suitable for application to equipment used in refining or downstream processes and equipment. Table1 List of equipment ISO15156 is applicable to materials used for the following equipment Permitted exclusions Drilling, well construction and well-servicing equipment Equipment exposed only to drilling fluids of controlled composition a Drill bits Blowout preventer (BOP) shear blades b Drilling riser systems Work strings Wireline and wireline equipment c Surface and intermediate casing Wells, including subsurface equipment, gas lift equipment, wellheads and christmas trees Sucker rod pumps and sucker rods d Electric submersible pumps Other artificial lift equipment Slips Flow-lines, gathering lines, field facilities and field processing plants Crude oil storage and handling facilities operating at a total absolute pressure below 0,45MPa (65psi) Water-handling equipment Water-handling facilities operating at a total absolute pressure below 0,45MPa (65psi) Water injection and water disposal equipment Natural gas treatment plants — Transportation pipelines for liquids, gases and multiphase fluids Lines handling gas prepared for general commercial and domestic use For all equipment above Components loaded only in compression a See A.2.3.2.3 for more information. b See A.2.3.2.1 for more information. c Wireline lubricators and lubricator connecting devices are not permitted exclusions. d For sucker rod pumps and sucker rods reference can be made to NACEMR0176 .