EN 489-2003 区域供暖管道.直埋式热水供应网用预隔热连接的管道系统.聚氨酯绝热和聚乙烯外覆层的钢管用接头组件
District heating pipes - Preinsulated bonded pipe systems for directly buried hot water networks - Joint assembly for steel service pipes, polyurethane thermal insulation and outer casing of polyethylene