Opening pressure provisions
to the boiler drum and superheater safety valve opening pressure provisions are as follows
（1）when rated steam pressure is less than 1.27MPa, the opening pressure is respectively working pressure of +0.02 MPa, and working pressure of +0.04 MPa;
（2）when rated steam pressure is greater than 1.27MPa, but less than 3.82MPa, the opening pressure is respectively 1.04 times and 1.06 times of the working pressure;
（3）When rated steam pressure is greater than 3.82MPa, the opening pressure is respectively 1.05 times and 1.08 times of the working pressure.
Economizer safety valve opening pressure is 1.5 times of the working pressure.
Pressure vessel safety valve opening pressure should not exceed the design pressure of the pressure vessel.
