Members of these local unions apply insulation to pipes, tanks, boilers, ducts, refrigeration equipment and other surfaces requiring thermal control of temperatures. The responsibilities of these mechanics, improvers and apprentices also include the manufacture, fabrication, assembling, molding, erection, spraying, pouring, mixing, hanging, preparation, application, adjusting, alteration, repairing, dismantling, reconditioning, corrosive control, testing and maintenance of heat or frost insulation. Workers also handle insulation materials made of fiberglass, rubber, calcium silicate and urethane. Insulators also do removal of asbestos containing material.