Maintenance of non standard socket flange

　　For the socket flange with complex shape, sharp change of cross section and large effective thickness, preheating should be carried out

　　The preheating methods are as follows: the primary preheating is 800? C, the secondary preheating is 500 ~ 550? C and 850? C, and the temperature rising speed of the primary preheating should be limited

　　2、 Heating:

　　Generally, the socket flange with groove and no hole, casting and welding parts and socket flange formed by processing should not be heated in salt bath furnace

　　Socket flange heating should have enough heat preservation time, according to the effective thickness of flange and conditional thickness

　　3、 Cleaning:

　　Before heat treatment, the socket flange and fixture shall be cleaned of oil, residual salt, paint and other foreign matters

　　The fixture used for the first time in the vacuum furnace shall be degassed and purified in advance under the vacuum degree not lower than that required by the workpiece

　　4、 Charging:

　　In the process of heat treatment, the flange is easy to deform and should be heated on the special fixture

　　The socket flange shall be placed in the effective heating zone