Typical Bend Formations for Tubular Heaters

 

Forming Tubular Elements

The MgO insulation used in tubular heating elements is compacted by reducing the element diameter. The elements are then annealed in a controlled atmosphere furnace to relieve the metal stressing (work hardening) that takes place during the rolling to size reduction of the sheath. Annealing brings the metal back to a soft state, allowing the element to be bent virtually into any configuration. However, since forming also work hardens the metal, some precautions must be observed in order to prevent the sheath from breaking during bending or developing stress cracking marks.
Note: Elements with tight bends and some applications require the bends to be recompacted in special dies to restore the insulation density and maintain dielectric strength.

Avoid bends within a minimum of 1/2" of the terminal pin and resistance wire junctions unless the bending radius is a minimum 3" (75 mm).

Tubular Element Minimum Bending Radius

Note: Smaller inside bending radius than listed in the table can be factory accomplished. It requires special forming techniques to prevent damage to the tubular heater. Consult ISE with your requirements.