Separation-prevented pipe joint which can be assembled from inside pipe

Claim 1

A separation-prevented pipe joint which can be assembled from inside the pipe, comprising a socket, a spigot inserted in said socket, a split lock ring fitted in an annular groove formed in the open end inner periphery of the socket said split lock ring being engageable with the outer peripheral surface of the spigot, a projection formed on the outer peripheral surface of the spigot so as to be engageable with said split lock ring axially from the inside, a seal member interposed between the outer peripheral surface of the spigot and a seal member supporting surface tapering from the inner side of the socket toward a seal member stopping projection formed on the inner surface of the socket at a place axially inwardly of said first projection, and means for urging said seal member toward said seal member stopping projection, said pipe joint being characterized in that (a) the portion of the inner peripheral surface of the socket between said annular groove and said seal member stopping projection has a length equal to the sum of the axial width of said spigot projection and the distance for the allowable axial relative movement between the socket and the spigot and also has an inner diameter such that there is defined a space between the inner peripheral surface of the socket and the outer peripheral surface of said spigot projection; (b) formed on the socket axially inwardly of said seal member supporting surface are an inner cylindrical surface defining a space for receiving said urging means and a radially inwardly extending innermost socket step surface which is continuous with said inner cylindrical surface and with which the end of said urging means engages; (c) a relay ring is interposed between said seal member and said urging means to maintain a fixed distance therebetween so as to prevent disengagement between the outer peripheral surface of the spigot and the seal member during the axial relative movement between the socket and spigot; and (d) means for preventing radial expansion of said lock ring from a fitted relation with the outer peripheral surface of the spigot and said annular groove comprises port means communicating with said annular groove from the outside of the socket, a flexible tube extending through said port means and interposed between the bottom of said annular groove and the outer peripheral surface of the lock ring, said flexible tube having inlet and outlet ends locatable in desired positions remotely of the pipe joint, and a filler which is injected in a fluid condition into said tube through said inlet end thereof and which thereafter solidifies, said outlet end forming vent means for the escape of air in said tube displaced by said injected filler.