Hermetic refrigerant fitting

A pipe coupling assembly includes two identical pipes each extending into an enlarged collar and then into a hemispherical socket each with a socket radius. A bulbous insert engages the sockets of the pipes. A clamping mechanism is disposed about the pipes and includes two blocks for holding the sockets into engagement with the insert. The insert has two necks both extending axially around the flow passage and fitting into the pipes. The insert defines a slot extending radially and circumferentially about the axis for allowing movement of two hemispheres relative to one another. Each of the hemispheres has an insert radius. The socket radii are greater than the respective insert radii for establishing a contact line between the insert and the sockets which becomes a contact band as the blocks move together.