Pipe joint for radiator element of thin material

A pipe joint for a radiator element, wherein the radiator element is a sheet of radiation absorbing material having a conduit passing therethrough in directions defined by the major surfaces of said sheet of radiation absorbing material, said conduit having a diameter essentially greater than the thickness of said sheet of radiation absorbing material and terminating at substantially right angles to an edge of said radiation absorbing material, said pipe joint comprising a block of deformable material adopted to be attached to said radiator element, said block being provided with a slot having a thickness substantially equal to the thickness of said sheet of radiation absorbing material, the bottom of said slot substantially conforming to said edge of said sheet of radiation absorbing material, said block being further provided with a first channel through said slot at substantially right angles to the bottom of said slot and having a cross-section substantially corresponding to the external dimensions of said conduit at the edge of said sheet of radiation absorbing material, said first channel passing through the bottom of said slot and terminating within the block beyond said slot, and said block being provided with a further channel through an edge of said block and communicating with said terminal end of said first channel, the surface area of the internal portions of said slot and said first channel being substantially greater than the internal surface area of said first channel.