EN 448:2003 區域供暖管道.直埋式熱水供應網用預先絕熱連接的管道系統.聚氨酯熱絕緣和聚乙烯外覆層鋼管用成套配件
District heating pipes - Preinsulated bonded pipe systems for directly buried hot water networks - Fitting assemblies of steel service pipes, polyurethane thermal insulation and outer casing of polyethylene