Adaptability in mechanical pigging: Why one tool can’t fit every fired heater

Across the petrochemical industry, no two fired heaters are exactly alike.

Differences in design, operating conditions and, most importantly, feedstock result in a wide range of fouling behaviors. Consequently, coke formation inside heater coils is seldom uniform, predictable or consistent from one unit to another. This fundamental reality defines one of the most critical principles in mechanical pigging: adaptability is essential.

At Decoking Descaling Technology (DDT), our proprietary DDT Piggs^® are engineered with interchangeable and adjustable appendages, allowing each cleaning run to be tailored to the specific characteristics of the heater and its coke accumulations.

Coke variability and why fixed pigging tools fall short

Different refining processes and feedstocks generate different fouling behaviors, and even within a single fired heater, coke hardness, thickness and adhesion can vary significantly from one section to another. Although severe coke is often associated with high-heat-flux radiant areas, especially in delayed coking service, critical deposits can also develop in less conventional locations such as roof tubes and shock (shield) tubes at the bottom of the convection section.

This variability exposes an important limitation in pigging systems that rely on fixed, non-adjustable appendages. The problem is that the required cleaning action is often localized, but the aggressive tool configuration is applied everywhere.

This lack of adaptability can lead to two undesirable outcomes: reduced effectiveness in challenging localized deposits and avoidable internal wear, including grooving or rifling, in tubes that no longer require aggressive cleaning. In those situations, controlled adaptability becomes essential for balancing cleaning efficiency with tube integrity.

DDT’s solution is rooted in decades of refinery experience and continuous tool development. Our piggs are designed to adapt progressively throughout the cleaning process, using fracture appendages initially to weaken and break coke deposits and scraper appendages on final-size and oversized piggs to remove the remaining coke.

This staged approach allows operators to match the tool to the condition, rather than forcing the condition to fit the tool, which directly influences cleaning efficiency and the level of contact with the pipe surface. Combined with DDT’s bidirectional control and realtime monitoring, this adaptability helps ensure that cleaning is both effective and controlled, even in demanding furnace environments.

At DDT, adaptability is not an added capability. It is the foundation of our pigging technology and the reason we continue to deliver consistent, safe and highperformance results across demanding fired-heater applications.

For more information, visit decoking.com.