As we all know, the importance of valve in the oil and gas pipeline is irreplaceable, not only can adjust the pressure of the pipeline, but also can distribute the flow direction of the medium, to a certain extent to ensure the safe transportation of the pipeline line. If we do not know the cause of leakage in valve, it may bring serious safety risks.
So, this passage is mainly about the cause analysis of valve internal leakage.
(1) valve leakage caused by improper switch limit
Improper switch limit adjustment is one of the main causes of valve leakage. However, due to the shrinking neck in the plug valve, the internal leakage of the medium can only be caused when the ball closure is 10 ~ 15 degrees away from the valve body.
（2）Valve internal leakage caused by impurities in the valve
The presence of impurities in the valve is another cause of leakage. These impurities can be sand, stones, rust, dust, etc., but also can be welding rods, wood rods, plastic products and other tools. Valve manufacturers in the process of production of valves, if the water pressure test is not done well after drainage, drying, corrosion protection and lubrication grease, etc., it is easy to cause internal rust of the valve, resulting in the production of pipe valve leakage phenomenon. In the process of installing oil and gas pipeline, if the protection work of pipeline is not done well, sediment, sewage and impurities may enter the pipeline, and the phenomenon of valve leakage may occur.
(3) internal leakage of valve caused by damage of sealing surface
As the pipeline works, oil and gas scour the pipeline for a long time. If there is a small area of damage in the pipeline during transportation, the small damage will become a big damage, which will lead to oil and gas leakage. In the actual pipeline work, if the violent loading and unloading or hoisting method is not reasonable, it will cause the integrity of the valve to be damaged, thus causing the leakage of the valve. In the process of welding the valve, if the welding spatter is spilled onto the closing member, the closing member will be damaged, which will cause damage to the sealing surface of the seat when the valve is in operation, further causing internal leakage of the pipeline valve.
(4) internal leakage of valve caused by improper maintenance
Pipeline maintenance is also a key link to ensure the normal work of oil and gas pipeline industry. In the process of pipeline maintenance, some managers may reduce the number of pipeline maintenance due to the high cost of maintenance, so that the valve shutters and seats are tightly locked, making it difficult to open and close the valve, and finally causing internal leakage of the pipeline valve.
Above all, knowing the cause of leakage in valve is very important for us. Only when we know the cause of the leak can we better prevent it.
The judgment of internal leakage of oil and gas pipeline valves are analyzed（新闻2）
From previous news we know what causes the internal leakage of valve. With the development of society and the progress of science and technology, the safety reliability and service life of valves in oil and gas pipelines are increasingly required. If the internal leakage of pipeline valve is not found in time, it may bring serious safety risks to the oil and gas industry, and then cause huge economic losses. So ,how to judge the valve internal leakage?
This paper mainly to judge the valve internal leakage.
(I) Formula method
When the valve is closed and there is no pressure in the back line or pressure vessel, it is possible to determine whether the valve has internal leakage by the change of pressure in the line or vessel.
(2) the blowdown method
When it is not possible to determine whether the valve has internal leakage through the back line or pressure vessel, we can use the blowout method. First we need the adjustment of valve to close position, especially the ball valve with a balance ball must be placed in a seated position, then slowly open the drain valve of the valve for drain work, if the oil and gas in the valve cavity can completely do, means that the valve without leakage, if not, then in existence of valve leakage.
(3) Flowmeter leak detection method
Flowmeter leakage measurement method is a very simple method to determine whether the oil and gas pipeline valve internal leakage. After a transfer joint, need to be ready in advance on the drain plug and drain valve valve assembly on a range of about 0.2 litres/minute float precision meter direct reading type or surface type gas flowmeter, finally from the flowmeter can directly read out the corresponding leakage, directly determine the existence of oil and gas pipeline valve leakage.
(4) Valve internal leak test tool method
We use the pipe fitting and the precision pressure gauge to make the valve internal leakage detection tool. If the pressure in the valve chamber does not rise after discharge, we can conclude that the pipeline valve has no internal leakage, otherwise the valve has internal leakage.
In recent years, the internal leakage of oil and gas pipeline valve occurs frequently, seriously affecting the safety production operation of the whole oil and gas pipeline work. In the actual pipeline transportation work, it is necessary to avoid the occurrence of valve leakage in oil and gas pipeline as far as possible. Constantly strengthen the valve operation, maintenance, maintenance management, actively looking for new technology of pipeline equipment maintenance, to avoid the occurrence of oil and gas pipeline valve leakage phenomenon.