The decoking process is essential for maintaining efficiency, sustainability, and equipment longevity in oil refineries, chemical plants, and energy facilities. Over time, coke residue—a byproduct of heating coal without air—accumulates inside furnace tubes, reducing heat transfer and system efficiency. Decoking and pigging remove these deposits, ensuring optimal performance and extended equipment lifespan.

Among the available cleaning methods, pigging has become the industry standard due to its safety, effectiveness, and environmental benefits. This article explores the decoking process, the pigging method, its step-by-step procedure, and the advantages of Petrotech’s custom decoking control systems.

Why Decoking and Pigging Matter

There are several ways to remove coke deposits from industrial furnace tubing. Traditional methods include:

Sandblasting – Uses high-speed abrasives to remove buildup.
Hydroblasting – Utilizes high-pressure water jets for cleaning.
Radiant Coil Cleaning – Applies thermal stress to break down deposits.
Steam-Air Decoking – Introduces controlled steam and air combustion to burn off residue.
Turbining – Uses fluid-driven mechanical cleaning, also applied in compressor and generator maintenance.

Among these options, decoking and pigging have proven to be the most efficient and environmentally friendly methods. Unlike high-temperature techniques, which can corrode or weaken tubing, the pigging method mechanically removes deposits without excessive heat, reducing the risk of pipe damage.

Step-by-Step Guide to the Pigging Process

Step One: Preparing the Pipes for Decoking and Pigging

Before pigging can begin, it’s essential to remove any remaining feedstock—the raw material processed through furnace lines. Operators use steam flushing to clear feedstock, ensuring that only coke residue remains inside the tubing. This preparation prevents contamination and enhances cleaning efficiency.

Step Two: Selecting the Right Pigs for Decoking

Each pipeline must be evaluated to determine pipe thickness, material composition, and buildup levels. These factors dictate the type, size, and number of pigs required for the job. Common pig types include:

• Hard-Claw or Decoking Pigs – Designed for furnaces, these pigs effectively remove hard carbon and iron sulfide.
• Calcium Scale Pigs – Used for cleaning pipelines with mineral deposits.
• Sludge Removal Pigs – Ideal for municipal, industrial, and seawater pipelines.

Each pig is equipped with evenly distributed pins, which scrape away residue without damaging pipe walls. Unlike thermal methods, this mechanical process prevents pipe corrosion and structural weakening.

Step Three: Inserting the Pigs into the System

After selecting the right pigs, operators insert them into the furnace tubing using specialized launchers. These launchers, installed at both inlet and outlet pipes, ensure proper positioning. Pressurized air then forces the pigs into the system, setting them in motion.

Step Four: Pushing the Pigs Through the Tubing

Using a closed-loop system, pressurized water propels the pigs through the furnace tubing multiple times. This repeated movement ensures complete descaling and residue removal. As the pigs travel, they dislodge deposits, which flow into a collection tank for disposal.

Once the cleaning cycle is complete, operators rinse the tubing, leaving behind a fully restored, high-efficiency furnace system.

Advantages of Decoking and Pigging Over Traditional Methods

The pigging method offers significant advantages over older techniques, making it the preferred choice for modern industrial decoking:

More Efficient – The process is five times faster than traditional methods, minimizing downtime.
No Disassembly Required – Unlike some approaches, pigging eliminates the need to dismantle and reassemble piping.
Eco-Friendly – Uses significantly less water than conventional techniques, reducing environmental impact.
Safer for Equipment – Eliminates the risk of thermal damage and corrosion caused by high-heat methods.
Cost-Effective – Reduces operating expenses by extending equipment lifespan and lowering maintenance costs.

With these benefits, decoking and pigging ensure optimal furnace operation while maintaining environmental sustainability.

Custom Decoking Solutions

While the decoking process can be completed in several different ways, the pig method is the optimal choice for cleaning fired heaters. It’s a streamlined process that’s ecologically superior to older methods, effective in the removal of buildup and waste, and gentle on pipes. This process can be easily managed with Petrotech’s decoking control systems, which can be retrofitted for compatibility with existing equipment to maintain productivity. To learn more about how Petrotech can create and install a specialized turnkey system for your facility’s current installations, request a quote today.