Study on the causes of valve internal leakage in oil pipeline and Its Solutions
Valves are very important to the whole oil pipeline system. Only by ensuring the smooth operation of the oil pipeline valves can the safety and reliability of oil and gas transportation be guaranteed. In general, valves may cause great damage in the process of installation and maintenance. Therefore, it is very necessary to study the causes ofinternal leakage of oil pipeline valves. At the same time, the consequences of accidents caused by internal leakage of valves will be very serious, which will bring huge economic losses to oil companies. Therefore, great attention must be paid. In general, during the operation of the oil pipeline, the main reason for the internal leakage of the valve is the failure of the pressure relief valve. Therefore, this paper makes a detailed study on the causes of the internal leakage of the pressure relief valve of the oil pipeline and puts forward some effective solutions, so as to solve the internal leakage of the valve of the oil pipeline thoroughly and ensure the operation safety of the oil enterprises.
At present, most of the oil pipelines are used in the form of single pipe transportation. In the process of oil transportation, the pressure in and out of the station is regulated by the regulating valve, so as to protect the pressure of the oil pipeline in advance. Therefore, in order to effectively ensure the safe and reliable operation of oil pipeline, many oil enterprises have applied water hammer relief valve to solve the problem of high pressure in oil pipeline and alleviate the damage of equipment, which has brought reliable guarantee to the economic benefits of oil enterprises. Through the use of water hammer relief valve, not only can effectively improve the circulation and safety of the oil pipeline, but also can greatly enhance the regulation of its economy. It has excellent automation properties, which can not only stabilize the oil pipeline and equipment, but also ensure the safe operation, so it is widely used in the oil pipeline.
Operation standard and application status of relief valve in oil pipeline
Valve is a key part of oil pipeline. Only by ensuring the safety and stability of valve operation, can the safety and stability of oil and gas transportation be ensured to a great extent. Generally, in the process of valve installation, repair and maintenance, it may bring different degrees of damage to the valve. Once the valve fails, it will directly affect the operation safety of oil transportation. It will not only cause serious economic losses to oil enterprises, but also endanger the safety of equipment and personnel. Therefore, oil enterprises pay great attention to the leakage of valves. At present, the detection technology of valve internal leakage in China’s oil enterprises is not very superb, so we can only avoid the valve leakage problem, reduce the occurrence of accidents, and maximize the economic loss of oil enterprises. Therefore, when selecting and using the pressure relief valve of oil pipeline, we must according to the relevant pressure standards and parameter requirements, combined with the actual water hammer in the oil transportation process The relief pressure value of overpressure relief protection equipment is calculated. At the same time, the appropriate water hammer relief valve should be selected according to the pressure change, fluctuation range and release state of the oil pipeline, and be installed effectively. Because the adjustment speed of the safety relief valve is very fast, and the number of relief is very large, there will not be a water hammer resonance problem, so that the pressure of the overpressure part and all the pressure can be released into the atmospheric tank, thus promoting the safe and stable relief of the water hammer pressure of the oil pipeline.
Structural mechanism of pilot water hammer relief valve
Fig.1 structure diagram of pilot water hammer relief valve
Usually, the components of pilot water hammer relief valve mainly include: valve core, spring, valve body, valve seat, pilot valve, pilot valve and pilot valve filter, etc. Its operation mechanism is mainly as follows:
- (1) If the pressure of the front pipeline of the water hammer relief valve is lower than the value set by the pilot valve spring, the slide valve will be located on the right side of the pilot valve chamber. At this time, the pipeline in front of the valve will be connected with the valve core cavity, so that the pressure of the valve core cavity is the same as the pressure in front of the valve, but the pressure of the valve core is the sum of the pressure of the valve core spring and the pressure in front of the valve, which is far greater than that in front of the valve The pressure will make the valve core close to the valve seat and keep the valve in the closed state all the time.
- (2) If the pressure of the front pipeline of the water hammer relief valve is higher than the value set by the spring, the side pilot valve chamber connected with the upstream pipeline will drive the piston to slide to the left, so that the pilot valve spring is tightly compressed and the valve core cavity is connected with the valve back. When the pressure of the valve core cavity is released to the back of the valve, the pressure of the valve core cavity will drop rapidly, so the valve core pressure is The pressure of the spool spring.
The main cause of internal leakage of pilot water hammer relief valve
Generally, there are two reasons for the internal leakage of pressure relief valve in oil pipeline, that is, the cone head is not recovered in place and the sealing parts fail. These two reasons will lead to the decline of sealing property of pressure relief valve in oil pipeline, and then cause the internal leakage of pressure relief valve, which will seriously affect the operation safety of oil pipeline.
The cone head is not restored in place
In the process of oil transportation, once the valve core cone head is not restored in place, it will seriously affect the sealing property of the relief valve, and then lead to the valve internal leakage problem, which is also the most common situation. For the pilot relief valve, in the process of oil transportation, if the pressure of the valve body is the same as that of the upstream pipeline, the pressure in the valve plug cavity will make the sealing property between the valve core cone head and the components, thus improving the sealing property of the oil pipeline. However, the pressure in the oil pipeline will be relatively large, so just open the valve It will make the valve core cone head out of the sealing base, thus completing the whole oil transportation process, which is also a very complete pressure relief process. Then, when the pipeline pressure returns to its original state, the pressure relief valve will be closed, and then the valve core cone head will return to its original position. However, if the cone head of the valve core is not restored in place, it will cause internal leakage of the pressure relief valve, which will bring great safety risks to the operation process of the oil pipeline, so special attention must be paid to it.
Failure of sealing parts
In the process of oil transportation, once the sealing parts fail, it will directly lead to the internal leakage of the pressure relief valve, which is also a very common phenomenon, which must be paid special attention to. For sealing parts, there are two main reasons for the failure of sealing parts, which are aging of sealing ring and impurities entering the valve body. First, the seal ring is aged. In the whole operation process of the pressure relief valve, the seal ring will be aged to varying degrees, which will reduce the sealing property of the pressure relief valve. Once the aging degree is serious, the sealing ring will not be tight or even broken, thus reducing or losing the sealing effect, which will affect the oil transportation process. Secondly, impurities enter the valve body. Once impurities enter the valve body, it will jam the valve body, which will inhibit its operation, and eventually lead to valve failure, and damage mechanical equipment. From the above, we can see that as long as the sealing property of the relief valve is reduced, the internal leakage of the relief valve will occur, which will affect the efficiency of oil transportation. In addition, in terms of the quality of oil and gas, if the oil and gas contains some impurities, such as stones or some materials with larger particles, these impurities will enter the oil pipeline during the transportation process. If the diameter of the impurities is between 0.3 and 0.88 m, it will seriously affect the transportation effect of the oil pipeline; if the diameter of the impurity exceeds 0.88 m, it will be seriously blocked It is necessary to pay great attention to the blockage of the oil pipeline, resulting in its failure to operate normally. In addition, if the hydraulic valve overpressure occurs, if the valve is closed immediately, the small diameter impurities in the oil and gas will stop at the original place, and slowly adhere to the sealing position, which will eventually affect the reset state of the vertebral body, make the recovery not in place, and then reduce the sealing property, resulting in internal leakage of oil pipeline valves.
Effective measures to solve internal leakage of pressure relief valve in oil pipeline
Once it is found that there is valve internal leakage in oil pipeline, effective measures must be taken immediately to avoid the expansion of internal leakage. In order to effectively avoid oil pipeline valve leakage, we can take effective detection measures before installation. Before installing the water hammer relief valve, all impurities or unused articles around the valve and inside the pipeline should be cleaned up. If conditions permit, the valve side pipe can also be cleaned and cleaned again to ensure that the pipeline is clean and free of foreign matters. After installing the relief valve, carefully check whether all the bolts of the valve are screwed well. Make sure that all the bolts are tightened and firmly, and clean the surrounding area.
Keep enough dust
Before the installation of pressure relief valve of oil pipeline, enough spare parts should be kept, especially some common spare parts of oil pipeline, such as sealing ring, bolt and spring, etc., which must be fully backed up. At the same time, a complete set of spare parts should be reserved for future replacement and maintenance. In addition, because many relief valves of oil pipelines in China are imported products at this stage, in order to avoid the phenomenon of rising product price and long transportation time, it is necessary to ensure enough spare parts for each, so as to avoid affecting the smooth operation of oil transportation due to internal leakage and ensure the economic benefits of oil enterprises.
Select appropriate pressure gauge
In order to effectively prevent the internal leakage of pressure relief valve in oil pipeline, it is necessary to plan the setting value of pressure relief valve reasonably, select the pressure gauge coordinated with the oil pipeline, and then carry out effective and comprehensive inspection and Research on the pressure gauge adopted by the pressure relief valve, so as to ensure the accuracy, reliability and safety of the pressure relief valve, and avoid the oil pipeline on the basis The internal leakage of pressure relief valve occurs.
According to the above contents, we can see that the main cause of valve internal leakage in oil pipeline is the internal leakage of pressure relief valve, so it is very necessary to study the internal leakage of pressure relief valve. Generally, there are many reasons for the internal leakage of pressure relief valve in oil pipeline. It should be analyzed according to the specific situation of internal leakage, so as to find out the main cause of internal leakage of pressure relief valve of oil pipeline, and then according to the actual situation, put forward effective measures to ensure the normal operation of pressure relief valve of oil pipeline. At the same time, the relevant personnel should pay special attention to the opening of the water hammer relief valve, so as to ensure that the water hammer pressure is fully discharged, and ensure the safety and reliability of the oil pipeline operation, so as to promote the operation safety of oil enterprises and avoid the occurrence of valve leakage in oil pipeline.
Author: Zuo Mingjun
Source: China Valve Manufacturer – Yaang Pipe Industry Co., Limited (www.metallicsteel.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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