A pipe thread sealant paste composition comprising from about 30 to about 80 percent by weight of natural flake graphite particles of a size sufficient to pass through a 100 Tyler mesh sieve and a liquid carrier comprising a mixture of mineral oil and petrolatum, the paste composition preferably having a total ash content of no greater than about 1 percent by weight and containing leachable chlorides in amounts equal to or less than about 50 parts per million. The invention also relates to a method for preparing and applying the pipe thread sealant paste to pipe joints.