平头对接焊缝 square butt weld ; plain butt weld

留隙平头对接缝 open square butt groove ; square butt groove

平头对接接头 plain butt joint ; square butt joint

平头开口对接焊缝 open square butt weld

平焊对接接头 downhand butt joint

平头开口对接焊 open square butt welding