Steam Tracing Method Definitions
System components can include bare or convection tubing, conduction tubing, clamp-on jackets, fully jacketed piping and heat transfer compounds.
Bare or Convection Tracing: Tubing attached to a pipe without the use of heat transfer compounds or other aids. Sometimes referred to as “conventional tracing,” the steam tubing can be bare or have a polymer jacket to reduce burn risks. The tubing is attached to the heated pipe with stainless steel straps, tie wire or high temperature adhesive tape. Heat transfer is by convection from the steam tracer through the air space under the insulation to the process pipe. (The tube tracer will touch the pipe where secured in place, only.)
Conduction Tracing: Tracers that are thermally bonded to a heated pipe with heat transfer compounds so that the primary heat transfer is by conduction directly into the metal pipe or equipment. The conduction tracing surface area in contact with the heated pipe, when properly installed, is approximately two to three times the diameter of the tubing.
Clamp-On Pipe Heating Jacket: A rigid rectangular steel heater having one side concaved to very nearly match the radius of the pipe to be heated. For most applications, heat transfer compound is required to significantly increase heat transfer rates to the heated pipe. The contact area per unit length of the heated pipe is approximately 0.15 ft2 per foot (0.0457 m2 per meter) of pipe.
Fully Jacketed Piping: Sometimes referred to as concentric pipe jacketing, a larger pipe surrounding a smaller inner pipe is flooded with steam or heating medium to heat the process fluid. Generally the jacket is one pipe size larger than the inner pipe. “Jumpers” with fittings are required at every joint of pipe, whether flanged or welded.
Heat Transfer Compounds (HTC): Thermally conductive materials to eliminate air voids between a surface-mounted heater and the pipe or surface to be heated. These materials are produced in several different forms. Examples include:
- Extruded “rubbery-like” materials that soften and adhere to a substrate when heated above 200°F (95°C).
- Nonhardening mastic materials that provide a tacky, semi-adhesive bond
- Water-based or epoxy-based mastic materials that harden and provide some degree of a mechanical bond when cured.
It is important to note that the thermal conductivity of a heat transfer compound is important, but it may not be as significant as the overall heat transfer coefficient between the heater and the pipe or surface to be heated.
See the related feature article, "Steam Tracing 101: Compare Steam Tracing Methods."