Figure B-6. Self-energizing radial 0-ring seal for high pressures in internally 

 pressurized vessels. 



0-Ring Seals in Elastic Follower Ring 



The experimental evaluation of this seal arrangement has shown it to 

 be markedly superior to all the other seal arrangements experimented with 

 previously in this study. The superiority of this seal (Figure B-6) lies in its 

 ability to seal out low and high pressures, as well as to follow the axial and 

 radial dilation of the vessel without any loss in sealing ability. Its ability to 

 accomplish all this lies in its use of hydrostatic pressure contained inside the 

 pressure vessel to expand and translate the elastic follower ring so that it follows 

 the radially dilating wall of the vessel and the axially displacing end closure. 

 This self-energizing feature causes the seal to press harder against the end 

 closure and wall as the pressure is raised. In this manner, it is assured that 

 regardless of the magnitude of internal pressure or radial and axial displacement 

 of vessel's interior surfaces, no extrusion will take place in 0-rings even though 

 they are soft elastomers. 



Because of the self-energized elastic follower ring in which the 0-rings 

 are contained, no extrusion of the 70 shore-hardness 0-rings took place even 

 though the total radial clearance between the interior vessel wall and the end- 

 closure skirt was more than 0.032 inch at 20,000 psi of internal hydrostatic 

 pressure. When the internal pressure was released, the elastic follower ring 



70 



