Patent ID: 7331615

Claim:
A pipe union for interconnecting a first length and a second length of coaxial pipe, the pipe union comprising: a first annular pipe member attachable to said first length of pipe, said first annular pipe member incorporating a circumferential flange having a shoulder, and said first annular pipe member having a front face which faces said first length of pipe and a rear face which faces in a direction of said second length of pipe; a fastening member incorporating an inwardly extending flange with a central passageway adapted to fit around said first annular pipe member, said inwardly extending flange adapted to abut said shoulder as said fastening member is fitted over said first annular pipe member, and having thread means formed on an inner surface of said fastening member; a second annular pipe member attachable to said second length of pipe, having thread means formed on an outer surface of said second annular pipe member and adapted to receive and engage said thread means of said fastening member, said second annular pipe member having a rear face which faces said second length of pipe and a front face which faces in a direction of said first length of pipe; and a third annular pipe member having a central passage therethrough, said third annular pipe member disposed between said first annular pipe member and said second annular pipe member, said third annular pipe member having a rear face which faces in a direction of said second length of pipe and a front face which faces in a direction of said first length of pipe, said rear face of said third annular pipe member adapted to abut said front face of said second annular pipe member, and said front face of said third annular pipe member adapted to abut said rear face of said first annular pipe member when said thread means of said fastening member engages said thread means of said second annular pipe member, wherein a first portion of said rear face of said third annular pipe member comprises a convex surface and a corresponding second portion of said front face of said third annular pipe member comprises a concave surface, wherein said first portion is situated directly across from said second portion and both portions have equal vertical elevation with regard to a horizontal center axis of the pipe.