Abstract: In order to design the spherical diaphragm seal structure of channel cover of certain after-cooler accurately, this paper calculates and analyzes the radial displacement of the cylinder short section of the high-pressure channel under internal pressure according to the theory of elasticity and the relevant analytical formulas in JB 4732—1995 standard. And the finite element model analysis is adopted to compare and verify the results. Then combining with the impacts of main operating condition parameters, the optimum structure of the diaphragm is determined. The results show through verification of engineering practice that the radial displacement calculated by the analytical formulas of thin film in the standard in this case has sufficient engineering accuracy; the spherical diaphragm has more potential radial elastic compensation than the planar diaphragm, which can improve the stress condition of sealing fasteners; the internal and external attachments of group welding on the short section of the channel have strengthening effect, but it will cause notable non-uniformity of radial displacement distribution along the circumference position, which is not conducive to sealing.

Key words: diaphragm seal, seal design, stress analysis, pulsating load, channel