
A leaking joint in a pipeline is sealed by locating a separable mould around the joint to form in conjunction with the pipeline a mould chamber enclosing the joint. Sealant is injected into the mould chamber and the volume of the mould chamber is reduced by deforming a flexible wall of the chamber to pressurize the sealant to a pressure above that inside the pipeline until the sealant has solidified around the joint.











