DDT Pigging

The DDT Pigg

The DDT Pigg is available in diameters from 16 to 914mm, and is designed to traverse U-bends and short-radius elbows and plug heaters. DDT Piggs are designed to accommodate interchangeable cleaning appendages and studs, which are threaded into the body of the pigg. These cleaning appendages are radially dispersed in a clockwise or counter clockwise pattern that provides a complete, 360° cleaning action.

The DDT Process

Pressurised water is used to push the pigg through the fouled heater tubes. The DDT process operates nominally in a pressure range of between 75 and 200psi, meaning risk of damage to pipelines is negligible. The pressurised water flows around the pigg and past the cleaning studs, removing build up on the pigg itself and pushing these loose deposits ahead of it and into the collection tank.

The DDT process is bi-directional; allowing the cleaning pigg to traverse the heater tubes in both directions, and is also the only process with the ability to direct the pigg to focus on areas with increased contamination.

Build up in heater tubes is removed in a tightly controlled series of incremental cleaning runs. The process uses a closed loop, self-contained hydraulic system, making it a very safe and environmentally friendly option. As the process uses no chemicals and works at ambient temperatures, it can be used to clean convection sections, external crossover lines, and other sections of pipeline that cannot be de-coked by steam-air methods.

Throughout cleaning operations, hydraulic driving pressure and the flow rate vs. time is continually monitored and recorded. The resulting pressure profiles measure resistance to pigg travel, enabling the operator to determine the location and extent of deposit build up.