Conclusion Due to the particularity of coking unit process, the high-temperature pneumatic ball valve used in the unit should be regularly maintained and overhauled during the operation of the unit. In general, a comprehensive maintenance and overhaul shall be carried out for the valve in one cycle of coking unit operation to avoid the shutdown of the unit due to valve failure in the next operation cycle. Based on years of valve manufacturing experience, this paper analyzes the faults of this kind of high-temperature pneumatic ball valve in use, and carries out relevant maintenance work, which solves the practical problems for the refinery and achieves good results.

The outer circle of the butterfly plate of the pneumatic butterfly valve adopts spherical shape, which improves the sealing performance and prolongs the service life of the valve. Zero leakage is still maintained after more than 50000 times of opening and closing under pressure. The sealing elements can be replaced, and the sealing is reliable to achieve two-way sealing. The butterfly plate can be coated according to user requirements, such as nylon or PTFE. The valve can be designed as flange connection and wafer connection. The driving mode can be manual, electric or pneumatic.