The safety valve has been designed to protect high pressure vessels. A fracture plate made
of a circular thin plate is located within the safety valve. The circular thin plate has an outlet for fluid
release and to help decrease the pressure. As such, fracture of the circular thin plate can occur at the
appointed pressure. In this study, design variables of the safety valve were used to control fracture
pressure so that it was easy to apply in the development of a new model of a safety valve. Design
variables were fluid diameter of the safety valve, thickness of the fracture plate, filet radius of the
clamping bolt, fracture pressure, and clamped torque of the clamping bolt. Design variables were
selected, since the fracture experiment indicated that these variables might play a critical role in the
fracture of the circular thin plate. Fracture pressure was calculated by the finite element analysis
method and analyzed to affect the design variables on the fracture pressure. Using regression analysis,
main design variables such as the fluid diameter, the thickness and the fillet were selected and the
relationships of the variables were expressed by a regression equation. Furthermore, finite element
analysis method and the regression equation were verified comparing with the experiment result.