Dryseal pipe threads are based on the USA (American) pipe thread, however, they differ from the USA (American) pipe thread in that they are designed to seal pressure-tight joints without the necessity of using sealing compounds. To accomplish this some modification of thread from and greater accuracy in manufacture is required. The roots of both the external and internal threads are truncated slightly more than the crests, i.e. roots have wider flats than crest, so that metal-to-metal contact occurs at the crests and roots coincident with or prior to flank contact, see Figure 1. Thus as the threads are assembled by wrenching, the roots of the threads crush the sharper crests of the mating threads.