Patent ID: 8783693

Claim:
A method for sealing an annular space in a rigid conduit and a pipe, tube or duct extending through the conduit, the conduit being made of metal, metal alloy, stone or concrete and the pipe, tube or duct being made of a thermally weakenable plastic material, wherein the outer diameter of the pipe, tube or duct is equal to or more than 50% of the inner diameter of the conduit, wherein the method comprises applying in the conduit a layer of a thermally expandable rubbery material comprising heat expandable graphite concentrically around the pipe, tube or duct, and applying at each end of the conduit between the conduit and the pipe, tube or duct a sealant being made of a fire resistant polymer; the sealant being vulcanizable at room temperature under exposure to humidity; the sealant comprising polymer which is free from components which would on heating cause the polymer to expand to an extent larger than the extent to which the polymer itself expands on such heating so as to thereby be thermally substantially shape-retaining and size-retaining; and the sealant, after vulcanization, has a hardness within a range of 45-60 shore A.