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Bolt expansion with induction heating

Induction bolt heating

The use of induction heating for bolt expansion in high-pressure turbines is a powerful business tool. Its precise and localized heat is faster and safer than resistance and flame heating.
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What is induction bolt heating?

Expanding bolts with induction is the proven time- and labour-saving alternative to inefficient flame and resistance heating. With induction, a specially designed coil is inserted into the bolt. Rapid, precisely controlled and localized heat is then induced directly in the bolt. The heat expands the bolt by an exact, pre-decided length, making it easy to remove the nut.

 

What are the benefits?

Induction heat delivery is very accurate. Due to the heat being generated within the component, you only heat the part you want to heat, and thus the bolt threads with nuts stay cold during the heating operation.The heating process is so quick there simply isn’t enough time for heat to travel into the thread area. And of course, with induction there is no risk of rods melting inside the bolts—a common and time-consuming problem with alternative heating methods.

The EFD Induction bolt expansion solution is built around a small yet powerful mobile Minac converter and specially designed inductor coils. The Minac also comes in a ‘Twin’ version, where one converter is connected to two independent handheld transformers. This means an operator can work on two bolts at the same time—in effect achieving the productivity of two operators. Alternatively, two operators can work simultaneously, each with their own independent transformer.

Operator productivity is also enhanced by quick-release coils. It takes only a few seconds to attach differently sized and shaped coils to the handheld transformers.

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. 

 

Where is it used?

Induction heating for bolt expansion is used in high-pressure turbines at power stations, chemical plants and oil and gas processing plants.

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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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Images

Induction bolt heating

Induction heating is increasingly used to remove the giant nuts and bolts in power stations' turbines.

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 - bolt expansion

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

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.