Working principle and maintenance methods of hard sealed butterfly valves

Introduction:

The hard sealed butterfly valve is an eccentric metal sealing structure, with a sealing form of metal to metal sealing, interchangeable metal sealing ring to metal sealing, stainless steel plate and graphite composite plate sealing ring to metal sealing. In addition to electric, the driving forms of hard sealed butterfly valves include manual, worm gear transmission, pneumatic, etc. This type of valve should generally be installed horizontally in pipelines.

The butterfly plate of the hard sealed butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, with a rotation angle between 0 ° and 90 °. When rotated to 90 °, the valve is in a fully open state.

Working principle:

Hard sealed butterfly valve is a valve that uses a circular butterfly plate (sealing element) to rotate with the valve shaft to open or close the pipeline. It is mainly used as a shut-off valve and can also be designed to have functions of cut-off and throttling adjustment. Hard sealed butterfly valves are increasingly being used in low-pressure large and medium diameter pipelines. The butterfly plate of the hard sealed butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, with a rotation angle between 0 ° and 90 °. When rotated to 90 °, the valve is in a fully open state.

The hard sealed butterfly valve has a simple structure, small volume, and light weight, and is only composed of a few parts. And it can be quickly opened and closed by rotating 90 °, with simple operation. At the same time, this electric valve has good fluid control characteristics. 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, so the pressure drop generated through the valve is very small, so it has good flow control characteristics. Butterfly valves have two sealing types: elastic seal and metal seal. Elastic sealing valve, the sealing ring can be embedded on the valve body or attached to the periphery of the butterfly plate.

If a butterfly valve is required for flow control, the main thing is to choose the correct size and type of valve. The structural principle of hard sealed butterfly valves is particularly suitable for making large-diameter valves. Hard sealed butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, and water treatment, but also in cooling water systems of thermal power plants.

Maintenance method:

1. Hard sealed butterfly valves should be kept clean regularly during use, and the transmission threads must be lubricated regularly. If any faults are found, they should be stopped immediately to identify the cause and eliminate the fault.

2. The bolts of the packing gland should be tightened evenly and should not be pressed into a crooked state to avoid damage, obstruction of valve stem movement, or leakage.

3. During installation, the valve can be directly installed on the pipeline according to the connection method. In general, it can be installed at any position in the pipeline, but it needs to be easy to operate and maintain. Note that the flow direction of the shut-off valve medium should be from the bottom of the longitudinal valve disc upwards, and the lifting check valve can only be installed horizontally.

4. When using a hard sealed butterfly valve, it should only be fully open or fully closed, and flow adjustment is not allowed to avoid erosion of the sealing surface and accelerated wear. There is a reverse sealing device inside the gate valve and upper threaded globe valve. The handwheel can be turned to the top position and tightened to prevent medium leakage from the packing.

5. When opening and closing a hard sealed butterfly valve, a handwheel should be used. Do not use leverage or other tools to avoid damaging the valve components. Turning the handwheel clockwise means it is closed, and vice versa means it is open.

6. Before installation, it is necessary to carefully check whether the pressure and diameter marked on this valve meet the usage requirements, eliminate defects caused by transportation, and eliminate dirt on the valve components.

7. Valves stored for a long time should be regularly inspected, and exposed machining surfaces should be kept clean and cleaned of dirt. When storing, ball valves should be blocked at both ends and in an open state. Pneumatic butterfly valves and channels should be blocked at both ends and in a closed state. They should be neatly stored indoors in a ventilated and dry place, and stacking or outdoor storage is strictly prohibited.