Unique design of the junction between a thick pressure vessel shell and a thinner hemispherical head

Abstract

Considering the fact that the required thickness of a hemispherical head for pressure loading is only half of that necessary for a cylindrical shell, the authors have developed a proprietary junction of shell to hemispherical head where the head is thinner than the shell. In the past 5 years, more than 100 high-pressure vessels with such junctions have been manufactured and safely used in the People's Republic of China. Theoretical investigations as well as engineering applications show that such junctions are rational in structure, convenient in fabrication and low in cost. For example, for a vessel with an inner diameter of 1000 mm and design pressure of 31.4 MPa, using the new junction, the head weight is reduced by 54.3 and 27.4 per cent respectively in comparison with a forged flat head and a hemispherical head with equal thickness of shell. The larger the vessel, the greater the economic benefits it achieves. In this paper, the authors describe its basic structure, stress characteristics and the engineering design method for the unique junction.