Decoking removes buildups of scale inside industrial piping. Periodic scouring is necessary to keep pipes running smoothly and effectively, with a minimum of pressure loss, pollution, and other problems. Some companies perform this internally, while others may hire consulting firms for their cleaning. Such firms specialize in decoking and have a variety of tools available to allow them to select the best options for a given job.
One method involves running harsh chemicals through the tubing. They break up the scale and scour the walls of the pipes to remove it. Another option makes use of steam cleaning, where pressurized steam is used to blast material from the side of the piping. Both options can subject plumbing to high stress which may contribute to fatigue, causing it to fail early.
Mechanical decoking, sometimes known as pigging, is a cleaning method of choice in many industries. It is less likely to strain piping, and doesn’t come with the high environmental costs associated with chemical cleaning. In this technique, operators insert flexible scouring plugs known as pigs. They shoot through the piping, scrubbing it with nodules on their sides to remove scale. Water helps push them through and flush debris.
Multiple decoking passes can ensure that piping is as clean as possible. Some pigs have ultrasound features, allowing them to vibrate the scale to remove more of it. They can also be equipped with cameras to assess their effectiveness, allowing the operator to determine if another pass is needed to get the pipes as clean as possible. Technicians can choose from a variety of pigs designed for pipes of different diameters, lengths, and compositions to select the optimal tool for the task.
Frequency of cleaning can depend on the facility and what it handles. It is important to clean regularly to keep pipes functioning, but excessive cleaning can be expensive and may hasten the breakdown of pipes. Technicians can perform periodic inspections to determine when pigging is needed and check for issues like cracks indicative of metal fatigue. They can replace sections of damaged pipe as well as decoking to clean up functional plumbing.
Facilities typically keep decking logs to document when they last cleaned, and what kinds of material were found during the process. Records can help companies determine when to clean again and may also identify abnormalities that could indicate equipment malfunctions and other issues. For example, chemicals associated with partial combustion might indicate that furnaces are not operating efficiently.