Turbines consist of upper and lower casings, which are tied up with heating bolts for ease in assembly and disassembly. Maintenance for turbines is carried out on 18-month intervals and involves the work of disassembling large bolts and nuts bound up with the casings to check the functions of the rotor, blade, bearing, and re-binding. For such disassembly and assembly of large bolts and nuts, bolts are typically first heated for a long time using a conventional heating system. This can often generate heat deformation of the casing, as the heat is transferred from a heated bolt to the casing.

Induction heating technology provides a solution to the weaknesses of conventional heating. Induction heating is a highly effective technique that expands bolts over four times more quickly than conventional heating, while maintaining a twice lower external diameter temperature. Moreover, it has been proved that induction heating lowers thermal casing deformation by over 60% in comparison to the existing conventional method. Through securing the health of heating bolts and casing in routine maintenance, it is possible to prevent potential large scale accidents like steam leakage from taking place.

• Upper & lower shells are bolted together with large hollow bolts under extreme tension.
• Bolts are periodically dismantled for service and repair.
• Elongation occurs due to heating.
• Friction between nut and casing surface is greatly reduced as bolt is heated and stretched, thus reducing the torque required for nut removal.

• Hot elements create safety hazards.
• Slower heating rate allows heat to soak into surrounding shell.
• Slower heating rate increases down time of steam turbine/generators.
• Induction is Faster and Smarter Than Resistance “Fire Bars”.