This International Standard is applicable to pressure-vacuum relief valves protecting marine vessel systems, including cargo tanks, which may be subject to gas/vapour pressure or vacuum beyond the design parameters of the system/tank. This International Standard specifies the minimum requirements for performance and testing of pressure-vacuum relief valves, with emphasis on selection of materials, internal finish and surface requirements for pressure-vacuum valves installed on cargo tanks in tankers (see AnnexA). This International Standard specifies design and in-service performance criteria, operational testing and maintenance requirements. Design or manufacturing in accordance with this International Standard does not imply suitability for any given installation, it indicates that certain minimum requirements have been considered and that information necessary for determination of suitability is provided to the buyer of the equipment . This International Standard does not cover all test procedures for devices that prevent the passage of flame, such as flame arresters. Such devices can be used in conjunction with pressure/vacuum valves. NOTE1 Additional information for devices to prevent the passage of flame is found in the International Maritime Organization (IMO) “International Convention for the Safety of Life at Sea, 2009” (SOLAS), Chapter II-2, Regulation 4, and IMO Maritime Safety Committee (MSC) Circular No. 677 (MSC/Circ. 677), “Revised Standards for the Design, Testing and Locating of Devices to Prevent the Passage of Flame into Cargo Tanks in Tankers”, as amended. NOTE2 In addition to providing pressure relief, high velocity vent valves are devices that prevent the passage of flame. Where high velocity vent valves are installed on the pressure relief system and the vacuum relief valve is protected by a flame arrester, the standards of IMO MSC/Circ. 677, as amended, are applicable. ISO16852 is also an acceptable test standard for devices to prevent the passage of flame.