Tube coupling

A tube coupling of the type having a socket and a plug, each having a fluid flow passage extending therethrough, and valve means mounted in the flow passage through at least one of the socket and plug for axial movement between a first position for closing said flow passage and a second position for opening said flow passage, said valve means being normally biased towards said first position by spring means when said socket and plug are disconnected, and adapted to be moved to said second position when the socket and plug are coupled together, characterized in that at least those portions of said socket and plug which will be exposed to fluid during the use are formed of fluorocarbon resin, said spring means being disposed in said flow passage and comprising bellows made of fluorocarbon resin having continuous helically extending pleats.