Month: November 2021

Ordinary gate valves, ball valves, and globe valves are strictly prohibited for adjustment due to their structural characteristics. But in process design, it is generally used for mediation. Due to the adjustment and use, the valve seal is in a throttling state for a long time, and the impurities in the oil wash out the seal and damage the sealing surface, resulting in lax closing or the operator has damaged the sealing surface to achieve the seal, cause the valve to be over-closed and over-opened

1.Clarify the purpose of the valve in the equipment or device, and determine the working conditions of the valve: applicable medium, working pressure, working temperature, etc.

2.Determine the nominal diameter and connection method of the pipeline connecting with the valve: flange, thread, welding, etc.

Differential pressure usually refers to the pressure difference between two points of the valve in the pipeline, such as the pressure difference between the front and back of the valve, the pressure difference between the two sides of the double flange, and so on.

Wafer butterfly valve is one of the most common types of valves in industrial pipelines. The wafer butterfly valve itself has a relatively small structure. You only need to put the butterfly valve in the middle of the flanges at both ends of the pipeline, and use stud bolts to pass through the pipeline flange and butterfly valve is locked to control the fluid medium in the pipeline. Wafer butterfly valve is especially suitable for places with narrow space or short distance between pipelines. When the butterfly valve is in the fully open position, the thickness of the butterfly plate is the only resistance when the medium flows through the valve body.

Under the following working conditions, butterfly valves are recommended:
①Require throttling, adjustment and control flow;
②Mud medium and medium containing solid particles;
③Occasions where the valve structure length is required to be short;
④Occasions requiring fast opening and closing speed;
⑤Occasions where the pressure difference is small.

The butterfly disc of the wafer butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0°-90°, which can play a role in flow adjustment. When the butterfly plate rotates to 90°, the valve reaches the maximum Opening. The wafer butterfly valve is simple in structure, small in size and light in weight, and consists of only a few parts. Moreover, it can be opened and closed quickly by rotating 90°, and the operation is simple. At the same time, the valve has good fluid control characteristics.

1.The sealing surface is leaking, and there is debris in the butterfly plate and sealing ring of the butterfly valve.

2. The butterfly plate of the butterfly valve and the closed position of the seal are not correct.

3. The outlet is equipped with flange bolts that are not compressed or stressed.

4. The direction of the pressure test is not as required.

The valve disc of the handle butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the disc-shaped valve plate rotates around the axis, and the rotation angle is between 0°-90°. When the rotation reaches 90°, the valve is in a fully open state. This valve is generally installed horizontally.

Leakage of valve body and bonnet:

Reason:

1. The casting quality of iron castings is not high, and there are defects such as blisters, loose tissues, slag inclusions on the valve body and bonnet body

2. Freeze cracking;

3. Poor welding, there are defects such as slag inclusion, non-welding, stress cracks, etc.;

4. The cast iron valve is damaged after being hit by a heavy object.