Valve pressure testing standard
Thread Content
Recently, during valve pressure testing, a problem that posed some confusion was that the internal leakage occurring during the testing of the sealing surfaces was closely related to the strength of the valve’s screw. I would like to ask the experts: what exact force is required to close a handwheel? If a F-ratchet is used for closing it, what is the maximum appropriate force, and beyond which level does it mean that the valve is defective? I’ve checked many standards but couldn’t find it; please give some advice. Thank you
Generally, according to standard specifications, it should not exceed 360 N.M; some standards prohibit the use of extended rods for operation! However, at present, the capabilities of domestic manufacturers and their manufacturing precision have a significant impact on the torque of valves. However, for valves with forced sealing such as gate valves, as long as the medium contains no impurities or particles. The sealing surface is not scratched, so generally there will be no problems with the seal! As long as you close it tightly, there will be no leakage due to poor sealing. As for the required force, the operating torque varies for different valves. It can be calculated (using torque formulas), or measured directly (using a torque wrench) ； But the difference is quite large. It makes no sense!
There seems to be no mandatory requirement for this; generally, it’s sufficient to close the small valve manually. If the valve stem cannot be turned, then custom-made tools may be needed. As long as it becomes obvious that the valve stem cannot be turned, one should avoid forcing it – especially when using custom-made tools and applying excessive force, as this could very well cause the valve stem to break. . . .