Positive seal steel coupling apparatus and method therefor

Claim 1

Method of building a pipeline by joining the marginal ends of adjacent pipe joints to opposed sockets of a pipe sleeve, comprising the steps of: (1) selecting a pipe which has a constant diameter marginal end; (2) making a pipe sleeve and forming a socket into the pipe sleeve such that the inside diameter of the socket is smaller than the outside diameter of the marginal end of the pipe; (3) forming circumferentially extending substantially constant diameter cutters about a first marginal length of the inside wall surface of the socket and forming a smooth bore along a second marginal length of said socket, said smooth bore having an inside diameter which is smaller than the outside diameter of said marginal end of said pipe, so that the marginal end of said pipe is held within the smooth bore of the socket with great friction due to the close tolerance fit therebetween; making the inside diameter of the cutters 0.030-0.080 inches smaller than the outside diameter of the marginal end of the pipe; (4) inclining the cutter blades towards a medial part of the pipe sleeve and in a direction away from the pipe; (5) arranging the constant diameter marginal end of the pipe in facing relationship respective to the end of the pipe sleeve, with the longitudinal central axis of the pipe and sleeve coinciding with one another; (6) applying a sealant to the entire periphery of the marginal end of the pipe; and, (7) applying sufficient force to the pipe end and sleeve to force the marginal end of the pipe to move into the socket, whereupon the surface between the marginal end of the pipe and the pipe sleeve are deformed due to the difference in the inside diameter of the cutters and the outside diameter of the pipe.