the disclosure relates to a tube coupling sleeve having a throughway open at one end to receive an end part of a tube to be coupled therein . the sleeve has an end stop spaced from the open end to define the limit of insertion of the tube in the sleeve and an inner integral hollow spigot extends along the sleeve from the end stop through the open end of the sleeve to project into the tube . the outer surface of the spigot has annular ridges or ribs to grip the inner surface of the tube and hold it in place . the closed and of the sleeve has an encircling head to fit in a bore in a body and the head has an encircling steel star washer to lock the head in the bore .