Daily valve maintenance
1. The valve should be stored in a dry and ventilated room, and both ends of the passage must be blocked.
2. Valves stored for a long time should be inspected regularly to remove dirt and apply anti-rust oil on the processing surface.
3. After installation, it should be inspected regularly, mainly for inspection items:
(1) Wear of the sealing surface.
(2) Trapezoidal thread wear of the stem and stem nut.
(3) Whether the filler is out of date or not, and if it is damaged, it should be replaced in time.
(4) After the valve is overhauled and assembled, the sealing performance test shall be carried out.
Common problems and precautions in the maintenance of cast steel valves. Valves in operation, all kinds of valve parts should be complete and intact. The bolts on the flange and the bracket are indispensable, the thread should be intact and no looseness is allowed. The tightening nut on the hand wheel should be tightened if it is loose, so as not to wear the joint or lose the handwheel and nameplate. If the handwheel is lost, it is not allowed to replace it with a wrench. It should be timely. The packing gland is not allowed to be skewed or has no pre-tightening clearance. For valves in environments that are susceptible to contamination by rain, snow, dust, sand, etc., the valve stem should be fitted with a protective cover. The scale on the valve should be complete, accurate and clear. The seals, caps and pneumatic accessories of the valve should be completed. The insulation jacket should be free from dents and cracks.
It is not allowed to hit, stand or support heavy objects on the running valve; especially non-metallic valves and cast iron valves, it is forbidden
Maintenance work when valve is greased
The professional maintenance work of the valve before and after the production before the welding plays a vital role in the service of the valve. The correct and orderly maintenance will protect the valve, make the valve function properly and extend the valve. life. Valve maintenance work seems simple, but it is not. There are often neglected aspects of work.
First, when the valve is greased, the problem of the amount of grease is often ignored. After the grease gun is refueled, the operator selects the valve and the grease injection method to perform the grease filling operation. There are two cases: on the one hand, the amount of grease is less than that of the grease, and the sealing surface is accelerated by the lack of lubricant. On the other hand, excessive fat injection causes waste. There is no accurate calculation of the different valve sealing capacities based on the valve type category. The sealing capacity can be calculated in terms of valve size and type, and a proper amount of grease can be injected reasonably.
Second, when the valve is greased, the pressure problem is often ignored. During the grease injection operation, the grease injection pressure changes regularly in the peaks and valleys. The pressure is too low, the seal leaks or fails, the pressure is too high, the grease injection port is blocked, the seal grease hardens or the seal ring and the valve ball and the valve plate are locked. Usually, when the grease pressure is too low, the injected grease flows into the bottom of the valve chamber, which usually occurs in a small gate valve. On the one hand, the grease injection pressure is too high. On the one hand, the grease injection nozzle is checked. If the grease hole is blocked, the situation is replaced. On the other hand, the grease is hardened. The cleaning fluid is used to repeatedly soften the failed sealing grease and inject a new grease. . In addition, the sealing type and sealing material also affect the grease filling pressure. Different sealing forms have different grease filling pressures. Generally, the hard sealing grease pressure is higher than the soft sealing.
Third, when the valve is greased, pay attention to the problem that the valve is in the switch position. Ball valve maintenance is generally in the open position, in special circumstances, choose to turn off maintenance. Other valves cannot be discussed in terms of opening. The gate valve must be closed during maintenance to ensure that the grease fills the seal groove along the seal. If it is open, the seal grease will fall directly into the runner or valve cavity, causing waste.
Fourth, when the valve is greased, the problem of grease injection is often ignored. The pressure, grease injection amount and switch position are normal during the grease filling operation. However, in order to ensure the grease filling effect of the valve, it is sometimes necessary to open or close the valve to check the lubrication effect and confirm that the valve ball or the surface of the valve is evenly lubricated.
Fifth, when filling grease, pay attention to the problem of valve body sewage discharge and wire plug pressure relief. After the valve pressure test, the gas and moisture in the valve chamber of the sealed chamber are boosted due to the increase of the ambient temperature. When the grease is injected, the drain and pressure should be drained first, so as to facilitate the smooth operation of the grease injection work. After the grease is applied, the air and moisture in the sealed chamber are sufficiently replaced. Timely discharge of the valve chamber pressure also ensures the safety of the valve. After the grease is applied, be sure to tighten the drain and pressure relief plug to prevent accidents.
Sixth, when filling the grease, pay attention to the problem of uniform grease. In normal fat injection, the fat-producing hole closest to the grease injection port first comes out of fat, then to the low point, and finally to the high point, and the fat is successively produced. If it is not in accordance with the law or does not produce fat, it proves that there is clogging and clearing treatment in time.
Seventh, when filling the grease, also observe the problem that the valve diameter and the seal ring are flush. For example, if there is a ball valve, if there is an open position, the position limiter can be adjusted inward to confirm that the path is straight and locked. Adjusting the limit can not only pursue the opening or closing of a position, but should be considered as a whole. If the opening position is flush and not closed, the valve will not be closed. In the same way, if the adjustment is in place, it is also necessary to consider the corresponding adjustment. Make sure the valve is at right angles.
Eighth, after the grease is applied, the grease injection port must be sealed. Avoid the entry of impurities, or the oxidation of lipids at the grease injection port. Apply anti-rust grease to the cover to avoid rust. So that it will be applied the next time.
Ninth, when filling grease, it is also necessary to consider the specific issues in the future delivery of oil products. In view of the different qualities of diesel and gasoline, the ability to flush and decompose gasoline should be considered. In the future valve operation, when encountering the gasoline section, timely replenish the grease to prevent wear.
Tenth, when filling grease, do not ignore the grease filling on the stem. There is a sliding bushing or packing on the valve shaft, and it is also necessary to maintain the lubrication state to reduce the frictional resistance during operation. If the lubrication cannot be ensured, the torque is increased during the electric operation, and the switch is laborious during manual operation.
Eleventh, some ball valve body is marked with an arrow, if there is no English FIOW handwriting, it is the sealing seat action direction, not as a medium flow direction reference, the valve is in the opposite direction. Typically, a two-seat sealed ball valve has a two-way flow direction.
Twelfth, when the valve is maintained, pay attention to the water in the motor and its transmission mechanism. Especially the rain that infiltrates during the rainy season. One is to rust the transmission mechanism or the transmission bushing, and the other is to freeze in winter. The torque caused by the operation of the electric valve is too large. Damage to the transmission components may cause the motor to be unloaded or the over-torque protection may not be electrically operated. The drive components are damaged and manual operation is not possible. After the over-torque protection action, the manual operation also fails to switch. For example, forced operation will damage the internal alloy parts.
In summary, valve maintenance is really treated with scientific attitude, in order to achieve the desired effect and application of valve maintenance work.
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