The self-sealing parallel double-gate gate valve is relatively simple and effective. The automatic-sealing parallel double-gate gate valve adopts a spring-type structure. The closing part is composed of two gates, and a spring is installed in the middle. The purpose of these springs is to maintain sliding contact with the upstream and downstream sealing surfaces and to increase the sealing force at low pressures. The gate is constrained within the band hole so that it does not open unrestrictedly when in the fully open position.

However, the function of the spring is often not as assumed, so that both sealing surfaces can be pressure-tight, and a very large spring is required for this purpose. In any case, this is not necessary. Therefore, the self-sealing parallel double gate gate valve with a spring in the middle belongs to double-sided forced sealing when the medium pressure is not enough to overcome the spring force; but when the medium pressure is enough to overcome the spring force, and push the gate to press the outlet end At this time, it becomes a single-sided forced seal. At this time, the function of the spring is to prevent the vibration of the gate.

In steam pipelines or other occasions where the temperature changes significantly, due to different materials and changes in cross-section, different expansions will inevitably occur, which will cause certain deformations. It should be noted that when the two gates are free to expand and contract, the spring should also expand and contract with it.