Abstract: A back pressure valve includes a tubular body having pin and box connections at its outer ends and formed of two tubes connected by double step straight threaded connectors with a seat ring captured between the two tubes. A ball is urged against the seat ring by a helical compression spring. A triple slotted tubular spring support is screwed into the outlet portion of the body. A hex headed cylindrical post at the upper closed end of spring support fits snugly but slidably with the spring and centers the spring. The dimensions of the spring and spring support are such as to prevent the spring from buckling. The flow path through the slots and around the support is as large as that through the seat ring, which is about equal to that through the pin connectors of the body tubes, whereby the wall thickness of the pin connectors is large. The support can be removed with a socket wrench. A release tool can depress the ball off its seat to release fluid pressure.

Abstract: Pipe connection comprising "Hydril" type pin and box connectors with an annular groove formed in the pin connector at the juncture of the inner cylindrical land and the inner tapered seating surface and a seal ring of preferably circular cross section, e.g. an O-ring, disposed in the groove sealing between the pin connector and the box connector.