BS ISO 20602:2019 pdf free.Ships and marine technology一Check valves for use in low temperature applications一Design and testing requirements.
4.2 Working pressure and designed temperature The valve shall be designed to operate without failure or leakage at the extreme temperatures and pressure ranges expected in service.  Class and maximum working pressure shall meet the requirements of the standard class specified in ASME B16.34. The manufacturers and the purchasers may reach an agreement when Class exceeds 900. The working pressure and design temperature for these valves are shown in Table 2. 5.1 General structure of a check valve The valve shall be designed as a ‘swing’, ‘dual plate’ or ‘lift’ configuration. Function and standardization of the valve shall be satisfied with the following requirements. The manufacturers shall follow agreements with each other if there are minor differences from this document. 5.2 Materials- General Throughout this document, materials are specified for each of the various parts of the valve. In lieu of the materials specified, other materials may be used provided they are manufactured by the same process as the material specified, such as forging, casting, bar, or seamless pipe. In addition, the material shall be suitable for the operating temperatures of the valve and the materials shall have mechanical properties, including low temperature impact resistance, and resistance to corrosion equal to or better than the material specified for the specific valve part. 5.3 Body 5.3.1 Materials Materials shall be equal quality or better than the materials shown in Table 3; welded ends type valve materials may be used for ‘flanged ends’ type.5.3.2.3.1 Welding ends type  a] Socket welding ends 一Class 150, 300: to the requirements of Class 3 000 in ASME B16.11 一Class 600: to the requirements of Class 6 000 in ASME B16.11 Class 800 to 1 500: to the requirements of Class 9 000 in ASME B16.11 b) Butt welding ends Thickness of connected pipes under Sch.40s shall meet the requirements of Sch.40s and be manufactured according to ASME B16.25. 一Thickness of connected pipes over Sch. 40s: shall be at least the thickness of connected pipes and be manufactured according to ASME B16.25. Thickness of connected pipes shall meet the requirements of ‘pipe schedules’ given by the purchasers.BS ISO 20602 pdf download.