The ControTrace Heating Element

What It Is. The ControTrace (CT) Heating Element is a product specially developed by CSI to provide the processing industry an economical alternative to jacketed pipe while also providing substantially more heating capacity than tube tracing. The basic configuration of the element is a rectangle tube, formed of SA178 Gr. B boiler tubing, with one surface contoured to closely fit the outside of the pipe on which it will be placed. There are two basic sizes of rectangular configurations: 3/4" x 1-1/2" for nominal pipe sizes 1-1/2" and smaller, and 1" x 2" for nominal pipe sizes 2" and larger. The CT surface in contact with the pipe has a radius of curvature hat matches the pipe OD. For example, a CT element for a 3" pipe has a rectangular shape of 1" x 2" with one surface having a radius of curvature of 1-3/4" -- the same as 3" pipe. Individual elements are fabricated to specific lengths. The ends of the tubing are closed and inlet and outlet connections are added for heating medium transfer. The elements are fixed to the pipe with bands of strapping placed three to four feet apart. Before the banding operation, a thin layer of non-drying heat transfer cement usually is spread on the CT surface in contact with the pipe.

How It Works. At startup, the heating fluid enters the CT element which begins to heat the pipe. The element, which expands more rapidly than the pipe, maintains thermal contact with the pipe via the non-drying heat-transfer cement. The pipe area adjacent to the CT heats rapidly and transfers heat around the pipe wall to other pipe areas. If the pipe is empty or filled with static process, the system will reach a predictable equilibrium temperature based on the insulation thickness, ambient temperature, heating medium temperature, and the physical properties of materials and processes involved.

When pumping commences, assuming that the process has an equilibrium temperature lower than the heating medium temperature, the entire pipe wall (and process) takes on a more uniform temperature. This is due to the process picking up heat from the area adjacent to the CT element and giving up this heat to areas of the pipe wall that are not as hot as the CT area. This heat transfer mechanism works the same whether the pipe is fitted with a single CT element or multiple elements. CSI uses a variety of analytical tools to recommend to customers the amount of CT coverage needed for specific processes, operating conditions, and pipe sizes.