How To Maintain Valves?

The valve is the control part of the fluid conveying system, which has the functions of regulating, guiding, stabilizing and diverting. From the simplest globe valve to the valves used in the complex automatic control system, the varieties and specifications of valves are quite various. Therefore, in order to achieve the effect and purpose in the work, the maintenance of valves is very important. And we will introduce some basic maintenance methods in the following.

1. Routine Maintenance

The valve should be stored in a dry and ventilated room and both ends of the valve passage should be blocked. Valves stored for a long time should be regularly inspected and cleaned of dirt. It is better to apply antirust oil on the machined surface. After installation, the valve should be inspected regularly, mainly including the abrasion of the sealing surface and trapezoidal thread of stem and stem nut. In addition, we should pay attention to whether the packing is out of date and invalid. If there is any damage, it should be replaced in time. At the same time, after the valve maintenance and assembly, the sealing performance test should be carried out.

2. Precautions for Maintenance

All kinds of valves in operation should be complete and intact. Bolts on flange and bracket are indispensable. The thread should be intact without looseness. If the fastening nut on the hand wheel is found to be loose, it should be tightened in time to avoid wearing the connection or losing the hand wheel and nameplate. If the hand wheel is lost, it is not allowed to replace it with a monkey wrench, and the hand wheel should be equipped in time. The packing gland should not be skewed or has no tightening clearance. The valve stem of the valve in the environment that is easy to be contaminated by rain, snow, dust, sand and other pollutants should be equipped with a protective cover. The scale on the valve should be complete, accurate and clear. The lead sealing, caps and pneumatic accessories of the valve should be complete and intact. The insulation jacket should be free of dents and cracks. It is not allowed to knock or support heavy objects on valves in operation, especially for non-metallic valves.

3. Grease Injection Maintenance

When the valve is injected with grease, the problem of the amount of grease is often ignored. On the one hand, a small amount of grease injection results in insufficient grease injection, and the wearing of the sealing surface is accelerated due to the lack of lubricant. On the other hand, excessive grease injection results in waste. During the operation of grease injection, the pressure of grease injection changes regularly from peak to valley. The pressure is too low and the sealing may fail. If the pressure is too high, the grease injection port will be blocked, resulting in the hardening of the grease in the sealing. At the same time, attention should be paid to the valve in the switch position. The stainless steel ball valve is generally in the open position during maintenance, and in special cases, it is selected to be closed for maintenance. Other valves cannot be kept in open position. After the valve pressure test, the pressure of gas and water in the sealing chamber is increased due to the increase of ambient temperature. Therefore, blowdown and pressure relief should be carried out before grease injection to facilitate the smooth operation of grease injection. After grease injection, the grease injection port must be sealed to prevent impurities from entering.