GB1214889A - Pipe coupling - Google Patents

Abstract

1,214,889. Pipe couplings. ENGLISH ELECTRIC CO. Ltd. 25 July, 1969 [26 Nov., 1968], No. 56061/68. Heading F2G. A pipe coupling includes a first body member 11 having an axially disposed divergent internal wall 16, a second body member 12 for mounting on and movement along a pipe 10 to be secured in the coupling, and a deformable ferrule 14 for mounting on the pipe between the two body members, the ferrule having an internally relieved leading end 20 for contacting in use the said internal wall and internally near its leading end one or more annular inwardly-directed sharp cutting edges 22, and, further from the leading end, and inwardly-directed blunt indicating edge 24. Means are provided for drawing the body members together to compress the ferrule axially and thereby compress radially its leading end so that the cutting edge 22 or edges bite into the surface of the pipe 10 and the middle portion of the ferrule bows outwardly and thereafter the indicating edge 24 contacts the pipe to indicate, by way of a substantial rise in the effort required to draw the two body members further together, that the cutting edge is buried in the pipe sufficiently to provide a satisfactory seal of the coupling with the pipe. In a preferred embodiment the body members are screw-threaded and the trailing end 21 of the ferrule is frusto-conical, having a smaller cone angle than the frusto-conical inner wall of member 12. After assembly of the coupling the female body member 12 is screwed on to the male body member 11, the ferrule 14 being pushed along the pipe until its leading edge contacts the internal wall 16 as shown in Fig. 1. As member 12 is further tightened the leading edge 20 of the ferrule is forced inwardly by the convergence of the wall 16, and the wall of the ferrule at the trailing end pivots about the line contact made with the pipe at the inner diameter of the frusto-conical wall 19 until the whole of the bevelled trailing end surface contacts that wall, so that the ferrule bows outwardly and becomes permanently deformed. On further tightening of member 12 the cutting edge 22 contacts the outer surface of a pipe (Fig. 2, not shown) in this position the deformation of the ferrule is such that the second, blunt, edge 24 is lifted clear of the pipe surface. Further tightening of the coupling causes the cutting edge 22 to cut into the surface of the pipe, until further deformation of the ferrule brings the indicating edge 24 into contact with the pipe surface, as shown in Fig. 3. This results in an abrupt increase in the effort required to turn the coupling and thus indicates that a satisfactory seal has been made, and so prevents over tightening. In a second embodiment(Fig. 4, not shown) the ferrule has two cutting edges formed at its leading end, and the pipe 10 does not terminate at the shoulder formed in the male body member 11 but passes through it.