Standards for determining the structural length of valves
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When checking the structural length of valves, discrepancies from the actual on-site dimensions were found on multiple occasions (especially for valves with large diameters and high pressures). Apart from GB/T12221-2005, what other standards exist regarding the structural length of valves? I would appreciate guidance from those who are more knowledgeable on this matter. Thank you!
The requirements of the previous Three Modernizations standards for valves are not being implemented at present. Valve manufacturers act independently, taking into account factors such as their own patents and the future market for spare parts. So don’t rely on the valve manual. 1. Measure before purchasing; 2. Purchase from the manufacturer. Even so, there are no dimensions specified at the time of purchase; even from the same manufacturer, different batches may have varying dimensions.
Thank you! I understand a lot now. According to standard GB-12221, the length of a stop valve (DN450 PN4.0) is 1200 mm; however, on-site measurements show that it is 1050 mm. The length specified in GB-12221 for gate valves is indeed 1050 mm. I once encountered a manufacturer whose behavior was even more absurd: they used American standards for the valve flanges, but Chinese standards for the valve length. As a result, the valves they supplied were unusable. It’s really unbelievable.
Which manufacturer is this? Is it a private owner from Wenzhou? Total nonsense. . .