To prevent jetted fluid from overflowing from a tray type pan when a safety valve is operated for jetting steam by fixing a pipe to the bottom face of the tray type pan with the pipe vertical end part protruded above a cylindrical seal ring height.

When a safety valve is not operated, an expansion difference between a safety valve side pipe 3 and an exhaust pipe 1 can be absorbed because mutual fixing is not accomplished between a tray type pan 2 and a seal ring 4 and between the seal ring 4 and the exhaust pipe 1. On the other hand, when the safety valve is operated and steam is blown out, a pressure from the upper end part of the seal ring 4 is larger than an atmospheric pressure P working on the outside of the exhaust pipe 1, so that a force pressing the seal ring 4 downward relatively works, and consequently, the jetted fluid is prevented from jetting out from between the lower end of the seal ring 4 and the bottom face of the tray type pan 2.