Bare pigs are used as the first cleaning pig in a main cleaning sequence.

• A. Bare pigs
• B. White pigs
• C. Foam pigs
• D. Gel pigs

Answer: (A)

Starting with a bare pig relies on the idea that the first pass through a main line should be a simple mechanical scrub to loosen heavy deposits without introducing materials that could trap debris or leave residues. A bare pig has no foam, gel, or coating to snag solids, so it can scrub the pipe walls and push debris ahead while remaining easy to recover. This creates a clean baseline for the following pigs, which are used to polish, apply cleaners, or seal sections as needed. Using a pig with foam or gel properties too early could trap debris or leave residues that complicate later cleaning steps and reduce effectiveness. Opting for a bare pig first helps mobilize sludge cleanly and sets up the rest of the sequence for thorough cleaning.