How to solve the leakage problem of stainless steel knife gate valve

During the application of stainless steel knife gate valve, if there is a leakage problem, it will affect the usage of the valve. Different leaks require different solutions.

1. Valve body joint leakage

The flange is generally used as the connecting piece between the valve body and the bonnet. If the connection does not have enough tightening force or the connection is uneven, leakage will occur here. Technicians recommend that when flanges are used as joining tools, the method of diagonally fixing the flanges should be used. In addition, the gasket used for the connection must also be of good quality.

2. Packing leakage

The corrosion, temperature, pressure and other factors of the medium in the stainless steel knife gate valve have a certain influence on its sealing performance, which is the main reason for the sealing leakage. Therefore, when choosing the packing material, the characteristics of the pipeline medium should be considered according to the actual situation.

3. Pressure holes leakage

Some stainless steel knife gate valves have pressure holes left by the manufacturer during the pressure test on the bonnet. If the pressure holes are not tight enough, it is likely to cause the valve to leak. Therefore, when using a stainless steel knife gate valve, the pressing hole should be tightened first, or the screws and screw holes should be welded directly.

4. Maximum allowable leakage for metal seal

According to the standard MSS SP-81, for shell test of body, each valve shall we hydro statically pressure tested at 1.5 times the rated working pressure with no visible leakage allowed, leakage through the packing or gate seal shall not be cause for rejection. For the seat test, each valve shall be hydro statically pressure tested at 40 psi (2.8bar) differential pressure in direction of closure. Maximum permissible leakage shall be 40ml/min/NPS (1.6ml/min/DN).

Therefore, when solving the problem of water leakage of stainless steel electric knife gate valve, it is necessary to combine the actual situation to find out the problem and take the correct method to deal with it.