After the turbine is covered, install the bolts according to the bolt numbers and first perform cold tightening. That is, apply a torque of 700～1200 N.m depending on the bolt diameter to tighten the nut, then use an electric heater to heat the double-headed bolt. Insert the bolt heating rod into the heating hole of the cylinder bolt.

    After the bolt is heated and elongated, rotate the nut by a given angle. Thus, after the bolt cools down, it obtains a necessary initial stress. This initial stress ensures that the sealing of the cylinder and main steam valve joint surfaces is maintained even after bolt creep occurs within 20,000 hours of turbine operation, hence it is called the bolt hot tightening method. 


 



 Heating resistance wire: 2080 high-temperature alloy resistance wire;