BOLt heaters

Thermal expansion allows tightening and loosening


These heaters are inserted into the large hollow bolts, screws or studs. Generally used for heating of screws where solid and long lasting connection is essential. Heating of expansion screw enables tightening and loosening of the screw. After de-energizing and cooling, screw returns back to original length thus ensuring solid connection. Applications include assembly and disassembly of turbines, engine heads, dies, cylinders and large flanged connections. Required amount of heat is achieved by regulating voltage through regulating transformer. Special lengths, diameters and powers are available.


  • Power plants, turbines, generators
  • Heavy machinery and equipment
  • Large compressors, large cylinders
  • Motors, engine heads
  • Shipyards, ship engines
  • Large mechanical or hydraulic presses, die blocks
  • Steam or pressure vessels

Technical data

Type of heating



Heating strip: FeCrAl alloys or NiCr alloys
Ceramic insulator: Alumina


Diameter: Ø18, Ø24, Ø25, Ø26, Ø28, Ø30mm
Overal length: 300-1000mm
Heated length and unheated length acc. to customer request


Easy insertion into a hollow bolt


Terminal rods for electrical connection


Precisely wound heating tape on high quality ceramic insulators


Power: 2000-10000W
Current: 80-150A
Voltage: 10-50V

Regulating of voltage through regulating transformer

Alternative product: Cartridge bolt heater


  • Special dimensions and powers are available
  • Quick heat-up time for shorter cycles
  • Fast response, reduced thermal inertia
  • Minimum heat loss
  • High temperatures
  • Even and efficient distribution of heat

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