Abstract: A threaded connecting assembly includes a first threaded connecting member having a body portion, an end portion, a bore extending axially from the end portion enabling the passage of a fluid through the body portion, and a plurality of spaced apart three sided threads defining grooves therebetween projecting along an exterior surface of the body portion at the end portion, and a cap member having a plurality of complementary three sided threads adapted to mate with the plurality of the three sided threads of the first threaded connecting member by seating in the grooves, and an opening configured for engagement with the bore of the first threaded connecting member to provide a passageway for the flow of the fluid therebetween.