Common leakage problems and remedies of soft-sealed flange gate valves

The soft-sealed flange gate valve belongs to the replacement product of the gate valve, because the gate plate is wrapped by elastic materials such as rubber or tetrafluoroethylene, and the valve seat can also be made of elastic material. seal. The combination of soft and hard sealing form can well achieve zero leakage. And because the connection form is flange connection, it is named. It is widely used in fluid pipelines such as tap water, sewage, construction, petroleum, chemical industry, food, medicine, textile, electric power, shipbuilding, metallurgy, energy system and so on. The characteristics of the soft sealing flange gate valve are that the fluid resistance is small, the applicable pressure and temperature range are large, the flow direction of the medium is not restricted, and the sealing performance is good.
In procurement, the leakage inspection of soft-sealed flanged gate valves is always the first concern. To understand the tightness of the product, we must first understand which components of the gate valve are prone to leakage, so that we can achieve good prevention and remediation. details as follows:
1 Leakage occurs at the connection between the one gate valve and the other gate valve
If this happens, first check whether the connecting bolts between the gate valves are tightened. This is done to ensure that the gasket ring in it is fully engaged with the flange sealing groove surface. If a leak has occurred here, you can check the bolts and nuts in sequence and tighten them to the compression seal ring. Finally, check the size and accuracy of the gasket ring and the flange sealing groove surface, whether there is pitting, sand holes, blisters or impurities, and perform corresponding repair welding, repair or cleaning according to the situation.
2 The valve cover leaks
Bonnet leaks are usually caused by leaking packing seals. If there is such a problem with the seal, you can check the selection first. If the selection of the seal does not match the sealing groove, it is easy to leak. This problem can be solved by replacing the sealing ring or repairing the sealing groove. The occurrence of burrs, fracturing, and twisting of the seals may also lead to leakage and need to be replaced in time. Finally, check whether the sealing surface of each sealing groove is rough or have other defects. If there are defects, remove the defects or replace the damaged parts. Special attention should also be paid to the installation of the packing and the coordination of the joint surface of the packing seal. To check the installation of these packings, if it is found that the upper and lower packings are installed upside down, they should be removed and reinstalled according to the correct method.
3 valve body cavity surface leakage
In this case, the valve body may have casting defects such as sand holes and sand holes during the casting process, which are difficult to find before the pressure test. But leaks can occur in these places when pressure is applied. When this problem occurs, it needs to be repaired or updated.
4 Leakage at the valve seat gate
This is also a relatively common leakage phenomenon. There are two cases of leakage at the sealing surface and leakage at the root of the sealing ring. We can start by checking the accuracy of the sealing surface. Too rough and needs to be removed and reground. Next, check the sealing surface for pitting, indentation, blisters, cracks and other defects, and pay attention to the replacement of the gate or valve seat. Sometimes some valve seats with compression springs will leak due to the weakening of the elasticity of the compression springs. In addition, attention should also be paid to whether the T-shaped connection between the valve disc and the valve stem is too loose. If there is a slope, adjust it to its optimal size immediately.
5 Leaks caused by the entry of sundries
If foreign objects such as welding slag, iron filings, and impurities enter the valve body, it will also cause the valve disc to close less than the expected depth and cause leakage. In this case, the valve body should be removed and cleaned again.
6 Leakage caused by improper installation of valve seat
When installing the valve seat, it should be installed with special tools. If the valve seat is not installed in place, leakage will occur.