Why do so many pipe threads loosen and leak in service?
Conventional tapered pipe threads are normally tightened to a given torque and as affected by numerous pin and box tolerances, the thread dope used, the torque measurement accuracy, and the field temperature, they hopefully stop within a desired position range that will seal and develop rated connection strength. However if for any reason, the stop is not within the desired range or is changed while in service, then over tightening may prevent reuse, and under tightening may cause leakage and/or pin jump out. API 8Rd Threads and others, have allowable Root-Crest gaps per API Std 5B, too wide to for API 5A2 dope to seal, but may hold mill test pressure for ten seconds as specified, and after being under service pressure a few hours, dope oozes out and leaves leak paths through the threads. RPT Patent 5,427,418 teaches the use of Thread Compound having solid particles large enough to seal gaps between mating threads API Buttress Threads and other threads whose flanks are not in firm cont
