With the development of industry, the requirements for sealing rings are increasing. Various new sealing rings have replaced some traditional ones. Among them, the spring PTFE sealing ring is widely used because of its good sealing effect and normal operation under certain adverse conditions.

The spring PTFE sealing ring is composed of the spring covered with polytetrafluoroethylene. As shown in Fig. 1, the sealing effect of the external PTFE under the pressure P belongs to self tightening sealing, while the internal metal spring mainly plays a pre tightening role.

1. Under normal pressure, install the spring energized ptfe seals into the groove between seal 1 and seal 2 (as shown in Fig. 2). Due to the characteristics of PTFE itself, a certain pre tightening reaction force is generated by the spring, so that the whole sealing ring and the sealing element are in close contact, and elastic contact stress is generated.

2. Under the pressure of the sealing ring, the PTFE material will creep and slide elastically to both sides of the groove until it is close to the side of the groove cavity. At this time, the line contact seal will gradually become larger and tend to the surface contact seal. At the same time, under the action of pressure P, the inner ring spring deforms and generates a reaction force. Under the combined action of the pre tightening reaction force and the reaction force generated under the external pressure, the contact stress greater than the pressure of the sealed fluid is generated between the sealing surfaces to complete the sealing of the seal.

During operation, the sealing contact stress consists of three parts:

1) Contact stress caused by the interference of the outer diameter of the seal ring with the inner diameter of the groove

2) The stress generated by the medium pressure P after the sealing ring is assembled in the groove

3) The pressing force of the radial deformation acting on the spring on the sealing ring. Therefore, within the working pressure range of the seal, the contact stress of the sealing surface is always greater than the pressure of the sealed fluid to ensure sealing.