Sealing leaks in pipes and pipe joints

This invention concerns packing seals for leak sealing clamps suitable for on line leak sealing. The packing seals (26) are suitable for use between a sealing clamp (18) and a flange (16) or pipe being sealed, and fit by compression as well as by bonding to surfaces. The packing seals preferably comprise woven mineral or synthetic fibres impregnated with a thermosetting resin, particularly one that sets at a high temperature. The seals 26 are heated after assembly of the clamp 18 by, for example, the heat of the pipeline. The sealing clamps 18 comprise two halves bolted together and having grooves 24 for the seals 26. <IMAGE>