How should field bending be specified for industrial heating elements?

Industrial heating elements should not normally be bent on site. A radius tighter than the permitted minimum displaces the resistance wire and insulating fill, shifting power distribution and weakening dielectric strength. Lock the final shape and bend radius before production; if adjustment is unavoidable, follow the manufacturer's process and re-test insulation resistance and withstand voltage afterwards. Specify tube diameter, sheath material, watt density, power, IP rating, mounting, and temperature control, with an approved bending drawing. Check the measured radius against that drawing and verify thermal performance under real operating conditions.