An O-ring made of rubber exhibits excellent sealing performance with a wide range of applications. The highest sealing pressure can be up to 400MPa. The temperature ranges from −60 °C to 200 °C and the medium is low-corrosiveness. This paper proposes an O-ring sealing device for high pressure vessels, which can be opened and operated outside a cylinder. There are no bolts bearing the axial stress under the internal pressure load, and the sealing efficiency of this device is guaranteed by the dimension chain. The whole sealing device has no threaded connections except for the oriented screw which does not bear load under the working conditions. Based on this newly developed sealing device, a high pressure vessel with the design pressure of 60 MPa and the internal diameter of 700 mm used to simulate 6000 m deep sea environment is developed and investigated. This paper firstly introduces the rationale behind the design of the sealing structure for this high pressure vessel, and then discusses a finite element model of the cylinder end for this high pressure vessel and the stress classification method which is used to evaluate the safety of the critical sections. Lastly, the paper presents a set of experimental devices and a series of experiments which were carried out. The results show that the proposed sealing structure can be used in high pressure vessels. The results also verify the assumption of triangle contact pressure distribution between the shear ring and the cylinder end. It is hoped that this study will be of interest and value to researchers when they design the similar structures in the future.

Autofrettage process, adopted by the pressure vessel industry, enhances the static limit pressure of components. In addition, a significant increase in the fatigue life autofrettage components is also observed due to the inhibition of crack initiation and propagation. The application of autofrettage treated vessels can be extended to the power generation industry (fossil and nuclear), the petrochemical industry, the food industry (bacterial eradication container), and automotive applications (injection pump), among many others. In particular, spherical pressure vessels, due to their inherent stress and strain distributions require thinner walls compared to cylindrical vessels; therefore, they are extensively used in gas-cooled nuclear reactors, gas or liquid containers rather than heads of close-ended cylindrical vessels. In this paper analytical expressions have been derived for stress and strain during autofrettage process of spherical vessels with different material models. These formulas have been applied to evaluate the residual stresses, and optimized design in monotonic and cyclic loading conditions.