Criteria for selecting valves
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Dear teachers: On-site, there often arises the problem where the outer diameters of pipe flanges and valve flanges do not match. This issue occurs when different standards are used. In the standard SH/T3406 for general steel valves in the petrochemical industry, the JB79.1 raised-face integrally cast steel flanges are referenced. The flanges used in the SH series standards should be American standard flanges. The flanges used in JB79.1 are European-standard flanges; the dimensions of flanges under different standards vary. Why are incompatible standards being referenced?
When developing or referencing standards, incompatibilities between different standards may arise due to historical practices, delays in standard updates, or oversights during the standard’s drafting. Although SH/T3406 is primarily based on American standards, for certain components such as flanges, European standards like JB79.1 may be adopted for practicality or supply chain reasons; this mixing of standards can lead to size mismatches during installation on site. To address this issue, it is recommended to thoroughly examine and confirm the compatibility of all applicable standards at the early stages of project planning and design, and to carry out technical coordination or select products that adhere to unified standards if necessary. At the same time, such issues encountered in practical applications should be reported to the standard-setting bodies, in order to facilitate the revision and improvement of standards and reduce the occurrence of similar problems in the future. .