Abstract: Two embodiments of insulated pipework system are described. The first comprises an outer sleeve, an inner flow pipe and insulating material within the space therebetween and is characterised by the use of a longitudinally compressed elastomeric member in the space between the inner and outer pipes as the primary means for transferring longitudinal forces between the inner and outer pipes. The second comprises an outer sleeve pipe, an inner flow pipe, an insulating material within the space therebetween, other than hollow alumina-silicate microspheres, wherein a longitudinally compressed elastomeric member is provided at intervals in the space between the inner and outer pipes. Compression of the elastomeric member is preferably by way of rigid plates on either side thereof which compress an the elastomeric member. For example, bolts can be passed through bores in the plates and elastomeric member and tightened thereby to compress the said member.