Abstract: A plastic closure securely insertable into the end of a pipe, pipe coupling secured to the end of a pipe, tubing, casing or the like for protecting the internal threads from damage. The closure comprises a tapered sleeve having a pair of axially spaced, outer peripheral thread portions. One thread portion is adapted to tightly secure the closure to a pipe coupling having internal threads of the Buttress type in which the threads extend to the end of the coupling. The other thread portion is adapted to tightly secure the closure to a pipe coupling having internal threads of the API type in which the threads do not extend to the end of the coupling. In the latter type thread, the section of the pipe coupling between the ends of the threads and coupling is tapered or flared outwardly.

Abstract: A plastic closure securely mounted on the external threads at the end of a pipe, tubing, casing, or the like for protecting the external threads from damage. The closure comprises a tapered sleeve which is normally uncompressed and compressed by tightening a metal strap enclosing the sleeve for securing it to the pipe end. When the closure is mounted on the pipe end in its compressed condition, threads on the inner peripheral surface of the sleeve are urged into engagement with the external pipe threads for tightly securing the closure to the pipe end. The sleeve has a conical seat for the strap in its normal uncompressed condition, and in the compressed condition of the sleeve the seat is cylindrical relative to the axis of the sleeve. The sleeve has a flat surface on which the strap seal is placed and a slot for receiving a projection on the strap to prevent circumferential movement of the strap before and during tightening.