Ken Tashiro, Pipeline Technology center, Tokyo Gas CO., LTD.; Masatoshi Kubouchi, Department of Chemical Engineering, Tokyo Institute of Technology; Takashi Imagawa, Pipeline Engineering Center, Toho Gas CO., LTD; Yuji Higuchi, Pipeline and Facilities engineering Dept., Osaka Gas CO., LTD; Yasushi Morita, Pipeline and Facilities Engineering Dept., Japan Gas Association