Abstract: An insert for use in connecting two lengths of pipe, each having a plastic liner. The insert consists of an inner tubular member of plastics material for connection at either end to the plastic liners of two pipe lengths, an insulating sleeve surrounding a central portion of the inner tubular member and a ring of heat-resistant material overlying a part of the insulating sleeve to be positioned, when in use, beneath a location at which the pipe length is butt welded, wherein the insulating sleeve includes an insulating material which is at least partially enclosed with a sheath, such that the sheath can be mechanically connected to the interior of one pipe length.

Abstract: Device for arresting the propagation of a buckle in a double walled pipe. The device comprising an outer pipe wall having a defined external diameter and placed around an inner pipe wall, defining an annular space between the said outer and inner walls; providing predetermined regions in the annular space which are bounded between two sealing blocks with radially opposed faces which are in contact with the outer and inner pipes; placing a curable compound in each region and curing it the length of each region is at least equal to 0.5 times the external diameter of the outer wall.

Abstract: Device for arresting the propagation of a buckle in a double walled pipe. The device comprising an outer pipe wall having a defined external diameter and placed around an inner pipe wall, defining an annular space between the said outer and inner walls; providing predetermined regions in the annular space which are bounded between two sealing blocks with radially opposed faces which are in contact with the outer and inner pipes; placing a curable compound in each region and curing it the length of each region is at least equal to 0.5 times the external diameter of the outer wall.

Abstract: An insert (10) for use in connecting two length of pipe each of use has a plastic liner. The insert consists of an inner tubular member (12) of plastics material for connection at either end to the liners of two pipe length's, an insulating sleeve (14) surrounding a central portion of the inner tubular member (12) and a ring (16) of heat-resistant material overlying part of the insulating sleeve (14) to be positioned, in use, beneath a location at which the pipe length or butt welded. The insulating sleeve (14) comprises an insulating material (22) which is at least partially enclosed with a sheath (24) such that the sheath (24) can be mechanically connected to the interior of one said pipe length.