This document specifies minimum requirements for materials exposed to sour environments as defined in ISO 15156 (all parts). It does not provide guidelines for material selection. The selection of suitable materials for a specific service including any necessary additional material requirements remains the responsibility of the end user. Requirements related to sulphide stress cracking in corrosive petroleum refining environments included in ISO 17945 are not covered in this document. NOTE For the purposes of this document, NACE MR0175 is equivalent to ISO 15156 (all parts), and NACE MR0103 is equivalent to ISO 17945. The materials covered in this document are intended to be used in piping systems designed according to ASME B31.3 category D, and normal and high pressure fluid service as supplemented by ISO 13703-1. This document is applicable to offshore production facilities and onshore production, processing and gas liquefaction plants. Common requirements related to manufacture of piping and valve parts are included in Annex A and Annex B providing material datasheets and element datasheets, respectively. These material and element datasheets can be applied for applications other than piping systems, e.g. pressure vessels and pumps based upon assessment of the end user and conformance with the selected design code for the relevant equipment. This document does not cover requirements related to: çø non-metallic piping systems according to ASME B31.3 chapter VII or ISO 14692 (all parts); çø marine piping systems, e.g. ballasting piping system, covered by classification rules; çø subsea production systems; çø downhole equipment; çø transportation pipeline systems, including flowlines, designed in accordance with a recognized pipeline design code. Annex C contains guidance on how to comply with the European Directive 2014/68/EU on pressure equipment.