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 Typical Bend Formations

FT1

FT2

FT3

FT4

FT5

FT6

FT7

FT8

FT9

FT10

FT11

FT12

FT13

FT14

FT15

FT16

FT17

FT18

FT19

FT20

FT21

FT22

FT23

FT24

FT25

FT26

FT27

FT28

FT29

FT30

FT31

FT32

FT33

FT34

FT35

FT36

 

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

Element
Diameter
Factory Bend
Minimum R
Field Bend
Minimum R
Minimum S
in mm in mm in mm in mm
0.26  6.6 3/8  9.5 3/4 19.1 1/2 12.7
0.315  8.0 1/2 12.7 1 25.4 1/2 12.7
0.375  9.5 9/16 14.3 2 50.8 5/8 15.9
0.43 10.9 3/4 19.1 2-1/2 63.5 3/4 19.1
0.475 12 7/8 22.2 2-1/2 63.5 1 25.4

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 Tempco with your requirements.