EFD Induction becomes ENRX on March 27th.

Bolt heating system

Induction heating system for bolt expansion

The EFD Induction bolt expansion solution is built around a small yet powerful mobile Minac converter and specially designed inductor coils.

Fast, easy, accurate and repeatable heat delivery improves productivity. Induction bolt heating is at least 70% faster than other methods.


Mobile, flexible and easy-to-use

  • Mobile induction: You can move it around a workshop or factory floor. The transformer has 10 meter flexible connections.
  • Flexible: It can be fitted with various coils for various bolt dimensions. Induction coils can be changed in seconds.
  • Simple to operate: Handheld transformers (HHT) feature on/off and precise power controls. In fact, the HHT is as easy to operate as a regular electric drill. Flexible, water-cooled cables connecting the HHT to the converter allow easy access to bolts.
  • Twin power output: A Twin solution featuring two independent power outputs that can operate simultaneously. The same operator can work with two bolts at the same time. It is also possible to work on both sides of the turbine at the same time.
  • Reduced costs:  Faster heat delivery means you get a much shorter shutdown periode for the steam turbine
  • Improved quality: The microcontroller feature lets you pre-set heating cycles with ramp-up and dwell times. Precise repeatability of heating cycles is assured. The same amount of energy is applied to each bolt. A constant energy level and heating time is guaranteed.
  • Eco-friendly: No flames, no gas and virtually no radiant heat means a more comfortable, more productive working environment. That is good news for the environment too.



Safety first

In the bolt expansion process, focus on safety is vital for a consistent result and for avoiding damage to either personnel or the expansion bolt itself. All flash-over from coil to workpiece must be avoided, as high-energy currents weaken the metal structure inside the bolt. Glass fibre insulation holster, varnish lacquers and electronic coil to work-piece detection provides a triple safety on flash-over situations. 

Learn more

Induction heating for bolt expansion
Bolt heating

The use of induction heating for bolt expansion in high-pressure turbines is a powerful business tool. It’s faster than resistance and flame heating.

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Induction heating - bolt expansion

An EFD Induction Minac 25/40 Twin heating bolts on a steam turbine.

Bolt expansion with induction heating

An operator inserts a specially designed induction coil into the bolt.

Bolt expansion with induction heating

The end result of quick and safe induction bolt heating: an exposed turbine is ready for maintenance.

Induction heating at oil processing plants

Induction heating is a time- and labour-saving alternative to ineffecient flame and resistance heating for oil and gas processing plants, chemical plants and power stations.

Induction heating - bolt expansion

The use of induction heating for bolt expansion in power stations is a powerful business tool.