Electric heat tracing design from a temperature perspective

Many plant processes involve the transfer and storage of products in piping. Often it is found that the products being transferred and stored can freeze, become extremely viscous, or condense undesirably if allowed to cool to plant ambient temperatures. While it is sometimes possible to prevent excessive cool-down by a combination of insulation and flow maintenance during processing hours, it is usually not practical to do so during nonprocessing periods. Hence, the addition of heat to the insulated piping and equipment is a common plant requirement. Today, one of the more widely used techniques for adding the desired heat is electric heat tracers. This article presents various facets of the design process involved in attaining a functional heat tracing design. In particular, finite element analysis (FEA) is presented to provide new insight into the details of tracing design in three areas: (a) nonuniform heat flux conditions; (b) temperature variation about a traced pipe´s circumference; and (c) power output decline of a self-limiting heater on thermally nonconducting pipe.<>