A high strength, high temperature resistant roundsling for use as a restraint safety device. The roundsling uses a blend of fibers having characteristics of high strength, improved heat resistance, low weight, and improved handibility, as compared to roundslings assembled from non-blended fibers. Use of the roundslings of the present invention to secure sections of pipeline systems, will assist to maintain safety and reduce failure conditions in such pipeline systems that are subject to higher pressures and elevated temperatures. An exemplary and preferred range of the fiber blend for the inventive roundsling device are within a range of 30-70% Para-Aramid fibers and 70-30% LCP fibers, respectively. An exemplary embodiment of the present invention that has been tested is a roundsling manufactured to include a blend of fibers within the approximate range of 55-65% Para-Aramid and 45-35% LCP.