Selection of pipe specifications, flanges, etc
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This post was last edited by t Xiong Doudou on 2017-1-22 at 16:18. Since the existing Class A, highly toxic gas materials produce acids when in contact with water, pipes and fittings are made of S31608 (GB/T14976) material. The current maximum operating pressure is 15 MPa (gauge pressure), the operating temperature is at room temperature, and the pipe diameter is DN20. Question: 1. We plan to use integral flanges now. However, since this material is used for flanges that comply with national standards, the maximum allowable operating pressure of such flanges at 20°C is 14.7 MPa (as stated on pages 19 and 32 of HG/T20592-2009), which does not meet the process requirements. Can this situation only be handled using US standards? 2. If American-standard flanges are used, can pipes with Chinese-standard flanges be fitted with American-standard flanges? Can Petrochemical standard (Class B) flanges be used with American standard flanges? 3. Can flanges that meet American standards only be used with valves that also meet American standards? Which specification should be referred to? 4. Which standards should be applied during the construction and acceptance phases?
1. It is now planned to use a integral flange. However, since this material is used for flanges that comply with national standards, the maximum allowable operating pressure of such flanges at 20°C is 14.7 MPa (as stated on pages 19 and 32 of HG/T20592-2009), which does not meet the process requirements. Can this situation only be handled using US standards? In HG 20592, the maximum rating is PN160; if the temperature and pressure conditions exceed this value, flanges from the American series must be used (it’s not necessary to use standards specific to the United States), or flanges specified in HG/T20615 can be chosen. 2. If American-standard flanges are used, can pipes with Chinese-standard flanges be fitted with American-standard flanges? Can Petrochemical standard (Class B) flanges be used with American standard flanges? Using flanges in accordance with HG/T20615 works fine when paired with pipes that meet national standards; when used with pipes of SH/T3405 or HG/T20553(1a) series, American standard flanges can also be used in combination with national standard pipes, as long as the standards are those specified in HG/T20615. Flanges compliant with SH/T3406 standards can be used in conjunction with flanges that meet ASME B16.5 standards without any issues. 3. Can flanges that meet American standards only be used with valves that also meet American standards? Which specification should be referred to? Valves that comply with national standards are generally of the European type, while flanges that meet American standards are usually paired with valves of American standard. Gate valves: API 602, API 600; Globe valves: API 608; Butterfly valves: API 609; Check valves: API 594. 4. Which specifications should be applied during construction and acceptance? Domestic standards can be used for construction acceptance, such as GB 50517-2010 and GB/T 20801-2006.
Double-grade steel forgings, such as F316/316L, can be considered; in this case, the pressure rating can be chosen based on the 316 grade, which will certainly be sufficient
Are you saying that HG/T20592-2009 includes American standard flanges? Or should we use the American standard flanges per HG/T20615-2009?
S31608 is the same as 316; there is no need to use a different grade of steel.