Process Temperature Maintenance
Temperature Control of complex valved piping systems, such as those around pumping sets and manifolds, can create a problem for the designer.
All pipe sections are not subjected to the same flow conditions. Often, only 1 or 2 pumps are operational whilst the remainder are in the standby/no flow condition. A temperature sensor located on a flowing pipe may de-energise tracing on static lines when heat is actually needed and vice versa.
Freeze Protection of Pipework
In cold climates, water or chemical pipework often needs to be heat traced to prevent freezing. Thermal insulation alone is incapable of preventing freezing. A 25mm bore pipe at 5°C having 25mm thick insulation will reach freezing point within one hour in an ambient temperature of -10°C.
Steam at, say 150°C, is not a viable fuel source for simple freeze protection and of course, condensate returns may themselves freeze. Electric heat tracing having a low power output is the most convenient and efficient option.
The type of control system will determine operating costs.
Tanks and Vessels
Heat tracing is applied to tanks and vessels to ensure that products are stored at the correct temperature. Usually the system is designed to compensate for losses through the thermal insulation although there are some cases where there is a positive heat input to raise the temperature of the vessel under defined conditions. The thermal insulation is the first line of defence against unknown, and often unquantifiable, losses from a bare surface.