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How to use valves properly and maintain and repair

Date:2018-07-05 01:41:11 click:1647

How to use the valve correctly is the knowledge that the user must master. Only when it is used correctly, it will be used for a long time. Therefore, the hydraulic control valve center recommends that you carefully read the instruction manual before using the valve, strictly follow the instruction manual of the valve. Operation and maintenance, negligence and savvy are a major cause of valve damage.


We know that most valves require minimal maintenance, which means most valves do not have to be repaired often. Sometimes, even a small problem such as a simple valve stem leak often becomes a big problem due to negligence. What's more, some very dry operators do not close the valve as required by the technical specifications, causing the stem to bend or severely damage the closure. This happens from time to time.


The threaded joint of the stem nut and the stem should be lubricated regularly with lubricating oil, which not only reduces the friction between them, but also prolongs their service life. This is also a very important protection measure. If the worn stem nut is still in use, a break may occur so that the entire axial force of the stem is not supported and the valve will be rendered useless.


At the beginning of the gasket, a simple leak occurs, and finally the hazard of steam leakage is reached. In order to avoid this danger, the bonnet bolt should be properly tightened at the beginning of the leak; if the seat sealing surface is improperly selected due to material selection, it will start with a small amount of leakage, which may later extend to the groove leakage, and then there is insufficient opening height. This accelerates the erosion of the fluid and causes the valve seat to be completely damaged.


The reason for the bending of the valve stem may be caused by the operator turning the handwheel excessively after closing the valve.


There are many reasons for valve damage. In fact, similar situations may be avoided if the operator is slightly trained.


The use, maintenance and repair of several common valves are explained one by one.


The shut-off valve is a commonly used shut-off valve that is used to switch on or off the medium in the pipeline. In the piping system, the time for not operating the shut-off valve is very small, and therefore, it is to be regularly maintained.


A small amount of filler leakage can be solved by simply tightening the packing gland nut. However, when the packing is damaged, the packing must be replaced. When replacing the packing, the valve must be fully open to allow the upper seal to function (it is generally possible under pressure). When replacing, install the appropriate packing in the stuffing box and tighten the packing gland nut. Regularly check it later to prevent the gland nut from loosening.


When replacing the disc part, lift the valve stem, disassemble the valve cover, then install a new disc on the new holder, turn the valve stem until the disc is disengaged from the holder, with a new flap And the holder is replaced and inserted into the valve, and the operation of replacing the valve flap is convenient.


In order to grind the valve flap (which can grind the newer valve), a small amount of abrasive is applied to the valve flap and then ground. The grinding method is to place a shaft pin on the hole of the valve nut groove and the stem supporting head, place the assembly on the valve body, unscrew the connecting sleeve, and then alternately grind in the forward and reverse directions. Use the valve stem as a grinding tool, grind it after placing it in the abrasive, and the grinding should not be excessive. When the grinding is completed, the abrasive is removed and the threads are lubricated.


The function of the check valve check valve is to allow only one-way passage of fluid to prevent backflow of the medium.


The most common type of urea check device is the lift check valve. The valve flap moves up and down along the center line of the channel, and the action is reliable, but the fluid resistance is large, which is suitable for small and medium caliber occasions. Lift check valves can be divided into straight-through and vertical or angled. Straight-flow lift check valves can only be installed in horizontal pipelines, while vertical lift check valves should generally be installed in vertical pipelines, and the media flows from bottom to top, while angle lift check valves can only be installed in vertical Pipeline.


Special care should be taken when adjusting larger spring-loaded safety valves, as there is no sufficient ability to accurately verify the discharge pressure at the user, manufacturer or repair shop. No adjustments may be made to the spring-loaded safety valve unless it is accurately adjusted at the manufacturer or on the actual unit.