Abstract: In the preferred embodiment, this invention provides a threaded pipe coupling for connection with a conventional threaded pipe end so as to effect improved sealing against internal fluid pressure and against external fluid pressure as may be required in an oil or gas well. The coupling form causes the thread contact pressure to be greater at the maximum and minimum thread contact diameters than exists at intermediate points along the length of thread contact. An auxiliary plastic seal that will undergo thermal cycling is also provided.

Abstract: A large, high temperature, cost-effective butterfly valve with provisions for simple internal inspection and repair through a transverse access opening that is substantially smaller than the valve seat opening and which is repairable without necessitating removal of the valve body from the pipeline. A plurality of closure members that span the width of the valve seat opening are positionable in compact manner for removal through the small transverse access opening. A substantially annular seat is defined within the valve by a plurality of seat segments that are disposed in supporting and supported slip joint relation, thus permitting substantial radial expansion and contraction of the valve body without subjecting the valve seat structure to circumferential stresses.

Abstract: The object of the invention is to provide means to connect a valve bonnet with a valve that controls the flow of high temperature fluids such that, no leakage occurs and such that removable assembly may be accomplished without the use of large wrenches and high torques.From the bonnet depends a flange (50) formed so as to encompass the end of the valve body wall (35) so as to allow the end of the flange to be welded to the valve body wall as at (58) so as to seal between the body and bonnet and to withstand fluid and mechanical forces there between and to minimize thermally generated forces there between.The flange is made long enough to allow for a plurality of removals and reattachments and still be sufficiently flexible to relieve thermal stresses between the body and the bonnet.