Flame Straightening

Flame straightening is an efficient and long-established method of correcting distortions in metal caused by stresses occurring during the manufacturing process when heat is introduced

Stresses occur in metal when heat is introduced to the manufacturing process through welding or other methods. The subsequent cooling causes distortion or warping, which can impact on the quality of the end product, and means that remedial action is often required.

Improving these distortions using flame straightening is based on the principle that metals expand when heated and contract when cooled. 

If expansion is constrained therefore, compressive stresses build up and result in plastic deformation when the temperature is high enough. 

Upon cooling the deformation remains, thus removing the distortion.

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Flame straightening in action

This case study shows distortions present in steel plates with a large surface area prior to being flame straightened using LINDOFLAMM® burners, and after with the distortion removed.

Before & After:

The process

Although various fuel gases can be used, the highest flame temperatures and intensities for rapid heating are achieved with acetylene and oxygen.

The choice of flame straightening equipment is dependant on the type and thickness of material. For straightening large plates, such as decks and deckhouses on ships for example, LINDOFLAMM® adjustable burners with three or more single-flame nozzles are ideal. These are mounted on a small wheel car for easy movement across large surfaces.


Flame straightening can be used on the following materials:

  • Steel

  • Nickel

  • Copper

  • Brass

  • Aluminium

  • Titanium