Exothermic Welding Flux Hot Welding: The capacity of an earthing circuit to protect the safety of personnel depends on the quality of the connections made . SHENTONG exothermic welding is RENTONG ' s patent product in China . And it has the best quality in China as the same product in U.S.A. and U.K . So SHENTONG Exothermic welding powder is qualified by national authority test department Wuhan High Pressure Research Institute State Power Corporation of China with the testing reports . RENTONG is the only one who obtains this testing report at the present time . The principle of the exothermic welding consists of bring together a welding filler material and ignition agent in a suitable graphite mould. The shape of the mould, its dimensions , and the size of the weldmetal , are all dependent on the item to be welded and their size .