DDT® is the most effective and efficient cleaning technique, minimising shut down times, improving heater efficiency and prolonging the life of the heater. Using a unique polymer Pigg the DDT® process employs a closedloop, self-contained hydraulic system, making it very safe and environmentally friendly. By allowing the Pigg to traverse the heater tubes in both directions the DDT® process can control the Pigg travel over the most contaminated section only in a repeated back and forward motion.