US Patent 6991268 Pipe fitting having over-sized strengthened starter threads

A pipe fitting has a body with an internally threaded bore and at least one female starter thread. The at least one female starter thread is disposed either within the bore or immediately outside of the bore. The starter thread is axially aligned with the bore threads. The starter thread is made from a material which is stronger than the material from which the bore threads are made. The starter thread most proximate to the threads of the internally threaded bore has a pitch diameter which is at least two percent greater than the pitch diameter of the most proximate thread within the internally threaded bore.