The ball valve is mainly used to control the transportation of the petroleum liquid. The main function is to use the ball valve as a cut-off valve, that is, sometimes the oil transportation is closed by a ball valve for the sake of need, so that the oil flow is controlled to meet the needs of transportation and production, and it is also ensured good condition during transportation process. However, since the ball valve itself is not closed tightly or the use time is long during actual usage, the interior of the ball valve will be worn. Therefore, oil or natural gas will be prone to leakage during transportation, and the leakage of the ball valve is a very serious problem. It will be got by the following analysis of the main reasons for the leakage of the ball valve.
1. Reasons of ball valve leakage
(1) External conditions for ball valve wear, such as pressure, temperature difference etc.
In actual use, due to the fact that the ball valve itself is not closed tightly or due to the long time of use, the interior of the ball valve will be worn. Therefore, oil or natural gas is prone to leakage during transportation, and due to oil leakage, it will make the ball valve to wear more and more serious. The ball valve we use in the oil and gas transportation process is most commonly used and it works as the sealed, seated ball valve. The valve seat of this kind of ball valve is mainly divided into two kinds, one is the ordinary type valve seat, the other is the elastic valve seat. The role of ordinary valve seat is that the seat and the ball body are pressed under the action of the pressure of the liquid transported by the pipeline, and the material of the valve seat is changed through the compression to achieve the sealing effect. The role of the elastic valve seat is as same as ordinary valve seat, but the elastic valve seat itself has an elastic force to seal the ball valve. As the ball valve is sealed by the pressure between the valve seat and the ball, this results in the ball valve being susceptible to pressure. Once the liquid has changed the pressure of the ball valve, it will cause the ball valve to leak easily. And due to changes in the outside temperature, it can easily lead to ball valve wear.
（2）Mistakes in design
The leakage of the ball valve is mainly divided into temporary leakage, permanent leakage, true leakage and false leakage. Mistakes in design can lead to temporary leakage and permanent leakage. The main reason for temporary leakage is that Internal leakage due to changes in the external environment during the pipeline transportation. For example, it is easy to cause inner leakage of the ball valve under the changes in external temperature, pressure etc. The reason of permanent leakage is mainly the unreasonable design of the ball or valve seat, which can easily lead to the inner leakage of the ball valve.
(3) Mistakes in other areas.
Earlier we nnoted that the leakage of the ball valve is mainly divided into temporary leakage, permanent leakage, true leakage and false leakage. Mistakes in design can lead to temporary leakage and permanent leakage. Other leakage is mainly true leakage and false leakage. The true leakage is mainly due to the spherical or seat of the ball valve seal being scratched by foreign objects. Or because of the damage of the valve seat of the ball valve. This is what we call true leakage. The true leakage of the valve seat can be solved through certain technical means after the ball valve leakage. What we call false leakage is actually not related to the wear and damage of the ball valve. The false leakage of the ball valve is not actually caused by the wear or damage of the valve itself. This mainly means that the spherical surface, valve seat and soft seal of the valve are all in good condition and no scratch phenomenon occurs. The main cause of false leakage is due to foreign matter stuck on the joint surface of the valve seat and the spherical surface or incorrect setting of the valve position resulting in the valve. It is an illusion, not an true leakage.
2. Solution for the leakage of ball valve
(1) Regular inspection of the ball valve and valve.
As the ball valve mainly refers to a controller in the process of natural gas and oil in the transmission, it mainly plays the big role as cut-off valve to control the transportation of petroleum liquid by ball valve. Therefore, it is very necessary for the regular inspection of the ball valve and valve. As the valve position is determined by the mechanical limit of the valve, and the valve position can directly cause the leakage of the valve, so the ball valve and the valve must be checked regularly.
(2) Clean the pipeline .
Since there is the false leakage in the inner leakage of the ball valve, the main reason for false leakage is due to the foreign matter adhered to the joint between the valve seat and the spherical surface. Therefore, the cleaning solution is used to clean the pipeline and the valve, making the foreign matter stuck to the valve and the pipeline. After softening, the valve is repeatedly operated to remove the adhesive or impurities on the sealing surface. Finally, pressure gauges are used to observe pressure changes per unit time, and true leaks and false leaks can be judged.
(3) Correct operation and regular maintenance.
It is sometimes necessary to operate the valve as required to the oil and gas transportation process, so it requires the operators to strictly implement the operation procedures and specifications. And once the ball valve has an abnormal situation, it should be vigilant to find the cause of the abnormality of the ball valve and solve the problem. Since the ball valve is used for a long time, it is very important for the maintenance. Regular maintenance can increase the service life of the ball valve, and prevent the occurrence of problems.
3 . Conclusion
The ball valve, an essential part, is very important for objects such as oil and gas that are transported by pipelines. However, the leakage of the ball valve has become a relatively common problem during actual use. Therefore, it can get the methods for solving the inner leakage of the ball valve by the discussion of the reasons of the leakage of the ball valve, and it can also improve quality of the ball valve to keep guarantees for the safe transportation of oil and gas.