To prevent a spark accident ascribable to intrusion of dust into mutually mated faces of members to be tightened in the case where electrically conductive support arms and a support are tightened in an insulated state with a tightening bolt in arc furnace equipment.
Elastic O-rings 58 made of an insulation material, each having a shape of surrounding a bolt hole 50, are mounted on the mated faces of members 30, 38, 26 superposed on the mating members therefor to be tightened with a tightening bolt 22. Under this condition, the bolt tightening is carried out with the tightening bolt 22, and gaps among the mated faces superposed on one another are sealed with the elastic O-rings 58, thereby preventing dust from intruding into the inside of the bolt hole 50 and preventing a spark accidents ascribable to such dust.
NAGATANI TETSUHIRO
ITOU SHIYOUJI
