Silicon carbide foam pigs are used for cleaning lines with high-level hardness buildup as well as rust and millscale. The abrasive compound can be in loose grit form or in a heavy-duty strap. Models are available in 2, 5 and 8 pound per cubic foot foam density. The pigs are constructed from an open-cell polyurethane foam with a durable polyurethane elastomer coating in criss-cross pattern and silicon carbide material in loose grit or strap form.