After "steaming out" the residue feedstock of the assigned heater, pig launchers are installed on both the inlet and outlet pipes of a relevant furnace section. These launchers provide the connection points for the pressurized waterlines and permit the loading and unloading of the appropriate piggs.
Pressurized water, supplied from a pumping Module, pushes a flexible pigg through the fouled heater tubes. In the process, the protruding metal studs scrape and remove the deposits. A controlled amount of the water flows around the pigg and past the cleaning studs, flushing the loose deposits ahead into a collection tank. The appropriate diameter pigg, the height and the type of appendages, the amounts of water to bypass the pigg are all determined by the operator. A series of valves controls the direction the pigg travels. Since the fouling of heater tubes is not uniform throughout a furnace, the DDT operator has the ability to direct the pigg to travel over the most fouled section only.
This bi-directional pigg control method is a DDT patented process and ONLY DDT can provide you with this operating procedure. Other competitors cleaning runs are restricted to traverse from launcher to launcher only. This capability will also permit the cleaning of furnace tubes with changing pipe diameters and prevent the unnecessary repeated cleaning of less contaminated pipes, thereby reducing pipe abrasion. The DDT process operates nominally in a pressure range of between 75 to 200 psig, eliminating possible tube damage.