【Weekly Topic】How to operate on-site drain valves to prevent internal leakage? (2011626--2011630)

Our company uses ball valves for the drain valves, and there are indeed quite a number of cases of internal leakage. The method we use is to plug any slight internal leakage or no leakage with a wire plug (we rarely use drain plugs). I’m a newbie, so I’ll just share my humble opinion.

There are mainly two reasons for internal leakage in the drain valve: The first is internal leakage caused by problems in the quality of the valve’s manufacturing； The second is the problems caused by the operators on site when operating the drain valves; for example, excessive force used when opening or closing the valves can lead to damage to the sealing surfaces ； The proper techniques for operating valves are not mastered; for example, when closing a valve, it should be done slowly to allow high-speed fluid to wash away any accumulated dirt and debris. Valves that are closed in high-temperature conditions should be tightened again once the temperature has dropped. If internal leakage occurs in the drain valve during the operation of the unit, and if that valve is connected by flanges, it is possible to install a temporary blind plate; the valve can then be replaced during maintenance of the unit ； If the drain valve is butt-welded or socket-welded, pressure-containing plugging should be considered.

In the event of an internal leak: 1. If it is a flanged connection and not used frequently, a blind plate can be used to block it off. 2. If it is a threaded connection, an additional valve can be added for control. Of course, it would be better if the main pipeline could be depressurized and purged, by replacing the valve.

For ball valves, try tightening the screws on the valve body

1. Choose a reputable valve supplier and select the appropriate valve material. 2. In medium and low-pressure applications, ball valves should be preferred; check valves and gate valves should be used in series when flow regulation is required. 3. Strengthen training for operators on the use of valves, to prevent damage caused by forced closing when rust or weld slag gets stuck in the sealing surface.

First, it is necessary to know what medium is being emitted. You might be referring to steam or water. After ruling out valve quality issues: 1. The backflow often operates at a very low flow rate, resulting in wear of the sealing surfaces and leakage. 2. The medium contains solid particles that get stuck exactly when the valve is closed; it can be opened for flushing before being closed again. 3. The medium contains solid particles, which, when the valve is not fully open, abrade the sealing surfaces; therefore, the valve needs to be replaced. 4. The valve is closed too tightly, especially when hot; cooling and contraction then cause damage to the sealing surfaces. The above situations can be avoided through optimized operations. Satisfied?

Reply to 1# security: Causes include 1) quality issues with the valve itself, and 2) improper operation by workers. Solutions involve releasing pressure and replacing the seal, or replacing the valve; if pressure release is not possible, a blind flange can be installed or another valve can be connected in series

This post was last edited by shizhenwu0916 on 2011-6-29 at 12:36. For ball valves, try tightening the screws on the valve body. www.sifu4.com

This post was last edited by happybell on 2011-6-29 at 15:51. There are many reasons for internal leakage in valves, including internal factors such as incorrect selection, poor quality, unreasonable design, and substandard sealing materials, as well as external factors such as harsh operating conditions, improper operation, installation scratches, and rough or incorrect handling. If it’s not a real seal damage. Internal leakage can be resolved simply by tightening and adjusting the valve. If it is a genuine seal damage, the best solution is of course to stop the machine, replace the seal or the valve. If it cannot be stopped/failed to stop, repair must be carried out online while under pressure; there is a certain success rate for such repairs, and even professional teams cannot guarantee a 100% successful repair. In companies with advanced technology, once online repair is successful, the valves can be opened and closed freely, and their functional performance returns to its original state. If you want relevant information, please send me a message within the platform so we can all improve together.