Abstract: A pipe coupling includes two sealing rings, each corresponding to one of the pipes. A sleeve is disposed within a retention device. The sleeve has axial end portions, each of which rests against one face of the sealing rings. The retention device has inwardly open grooves, one side wall of which rests against the respective axially inner sides of the axial end portions of the sleeve. The other side wall of the inwardly open grooves exerts an axial force on the other faces of the sealing rings as the clip is clamped, thereby pressing the sealing rings against the pipes.

Abstract: An indicator device is provided for indicating that a set value of a clamping force of a tightenable clamp has been reached. The clamp has an approximately C-shaped clamp strip with first and second circumferential ends facing one another in a circumferential direction of the clamping strip and axial ends extending in the circumferential direction from the first circumferential end to the second circumferential end. The axial ends have radially inwardly projecting end face walls with a radially inner edge. Clamping jaws are connected to the first and second circumferential ends. The indicator device has at least one breakable indicator element for each one of the end face walls, wherein the breakable indicator elements can be placed onto the radially inner edge of the end face wall.