Tubular elements (or calrod elements) are the most simple and fundamental of all heaters. They are used to heat solids, liquids and gases.

The basic design lends itself readily to be bent or formed into any number of standard and custom shapes. The most common shapes are straight tube (terminations at opposite ends) and hairpin (u-shape) with the terminations at one end or side. Depending on the application, the hairpin (or calrod elements) shape can be bent back on itself (fold back style) or bent in a pattern that resembles a bugle shape. The advantage of these two shapes is to increase the surface area of the element, while maintaining a given immersion length, or the length from the terminations to the end of the element bend(s). These standard shapes are used extensively on screw plug and flange heaters, allowing for higher wattages and densities in smaller confines.

The construction of the tubular heater  (or calrod elements)involves determining the sheath material and diameter (determined by the application); loading it with the appropriate ni-chromium (resistance wire) based upon the length, resistance and wattage required; and filling/compacting it with magnesium oxide powder. Silicone rubber bushings are the most common end seals used, after which the terminations are affixed. Annealing and bending as per application design follows.

Tubular heaters  (or calrod elements) can be mounted any number of ways, in racks, clamped against surfaces, supported by mounting tabs affixed directly to the element, or cast-in to molds during the pouring process.

The most common termination on a tubular element (or calrod elements) is an ANSI 10-32 style connectors, but almost any standard electrical termination can be applied, included flag terminals, male/female spade or barrel connectors and specialized moisture resistant boots with wire lead exits.