Definition - What does Foam Pig mean?
A foam pig is a device, typically a cylindrical object with a cone-shaped nose, consisting mostly or entirely of foam that is used inside pipelines for a variety of purposes including removing debris that could lead to corrosion. The pig's foam composition allows it to maneuver through bends, valves and other geometrical transitions found inside pipelines.
Corrosionpedia explains Foam Pig
Foam pigs are primarily used to remove both loose debris and more troublesome contaminants such as mill scale. Foam pigs are also used for batching, which is an operation that is performed when different materials need to be sequentially transferred through the pipeline but cannot be mixed with one another, such as different grades of oil. Foam pigs are commonly used for batching operations because of their sealing ability. It is this sealing ability that also makes a foam pig an excellent choice for extracting product remnants from the pipeline.
Foam pigs are commercially available in a variety of forms. In terms of shape, they can be cylindrical, with or without a cone-shaped nose. A foam pig can also be spherical in shape. One foam pig may have multiple diameters to accommodate changes in the size of the pipeline.
A foam pig can be made entirely of foam with a coating that helps protect it as it removes material from inside the pipeline. It can also have brushes, bristles, or even carbides on its exterior, depending on the application.