PIPE SCREW JOINT WITH LUBRICATING FILM

摘要

A lubricating film, which has excellent seizing resistance, gas tightness, and rust preventive properties, can prevent the yield of a screw-free metal contact part even upon fastening at a high torque, and is free from any harmful heavy metal such as lead, is formed on a special pipe screw joint comprising a pin and a box each having a contact surface with a screw part and a screw-free metal contact part (a seal face and a shoulder part). This lubricating film contains one of or both a rosin and calcium fluoride, a metallic soap, wax, and a basic aromatic organic acid metal salt and preferably further contains a lubricating powder, magnesiumcarbonate and/or carbohydrate, particularly cyclodextrin.