Induction Bolt Heating
Induction Bolt Heating
How it is Done
The Bolttech Induction Heating System is a portable power supply that generates alternating magnetic flux fields in conductive metals to achieve rapid heating of components in the field. This process affords enormous time savings when compared to other methods, such as electrical resistance heaters and acetylene torches. Heating is accomplished with replaceable induction coils in a variety of shapes and sizes. They are connected to transmission leads of varying lengths with quick disconnects for rapid replacement. The unit is controlled remotely, so the operator can stand adjacent to the workplace and operate the heating process while monitoring the changing thermal characteristics.
Induction heating occurs when a material capable of conducting electrical current, not necessarily ferrous or magnetic, is placed in a varying magnetic field. The material becomes heated as a result of hysteresis and eddy current losses. Hysteresis occurs with magnetic materials, such as A193-B7 and B16 bolting, and is produced by retardation of the magnetization effect caused by the friction of the molecules, when the material is magnetized in one direction, then reversed at a very high frequency.
While hysteresis losses occur only in magnetic material to some degree, eddy current losses occur in any conductive material. This effect enables induction heating to be used with non-magnetic and slightly magnetic materials, such as 422 Stainless Steels, commonly used for internal components for high temperature inner turbine casings and bolting. Eddy currents are electrical currents induced by an alternating magnetic field. Simply stated, the induction heating coil acts as a a primary side of a transformer and the bolt acts as a secondary side, with the eddy currents flowing around within the mass of the bolt. Heating of the bolt occurs according to simple electrical principles. Because of relatively high power consumption by the current depth of penetration, heat cannot be dissipated rapidly, and the bolt thermally expands axially, thereby relieving pre-load stresses. The rapid heating process occurs from the stud hole out into the bolt with the heating area controlled by coil design, ideally concentrating thermal expansion in the bolt shank or mid-section area of the stud away from the threaded ends.
- Stop, throttle and control valves.
- Steam and gas turbine bolting.
- Boiler feed pump heads.
- Generator retaining ring removal and installation.
- Turbine joint assembly/disassembly.
- Reduces time required for thermal bolt elongation.
- Eliminates days and weeks from critical outage schedules.
- Creates a safer work environment.
Time is valuable and the more you can save on your next turbine outage will make a world of difference. Bolttech’s bolt heating technology guarantees significant time savings and cost benefits. If you are looking to cut time from your outage, our Induction Bolt Heating System is the surefire solution.
Be prepared and cut time on your next turbine outage. Bolttech’s new technology can save you hours, even days, during scheduled outages. Our complete line of on-site services and equipment can enable you to reduce downtime and get your units back on-line safely, quickly and cost-effectively.
