Stud pigs are used to remove extremely hard deposits and to decoke boilers, heat exchangers, and other severely restricted lines. Metal or plastic bolts or studs protrude from their bodies to cut into hard debris. Use caution: removing too much debris at once can cause a blockage. Operators typically have prior experience using these pigs in decoking or mining operations. Such applications often require extremely high pressures and flow volumes, although stud pigs are sometimes used in conventional pipelines to remove hard wax, black powder, or other deposits. All models use heavy-density foam to secure the studs and withstand demanding conditions.