DriTherm, Inc. manufactures DriTherm, the only closed cell, poured-in-place, waterproof pipe insulation available for underground pipe systems / tanks (-273°F to +500°F). The DriTherm formula has satisfactorily insulated / corrosion protected over 300 miles of underground piping, providing a dry, stable, environment of minimum heat transfer. DriTherm, the overwhelming choice for underground piping systems.