After "steaming out" the residue feedstock of the assigned heater, pigg 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 and into a collection tank. 
The appropriate diameter pigg, height and type of appendages, and 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 rubs is not uniform throughout a furnace, the DDT operator has the ability to direct the pigg to travel over the most fouled section only. Other competitors cleaning runs are restricted to traverse from launcher to launcher only. This capability will also permit the cleaning of furnace tubs 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 psi, to eliminate tube damage. 
Pigg® with assorted appendages It is the ONLY Pigg® design that incorporates interchangeable appendages. This patented design enables the operator to adapt to all conditions encountered in refinery heaters, thus providing optimum cleaning performance in the shortest possible time. About Us | The DDT Pigg | The DDT Process | How We Clean | Equipment | Service | Contacts |