對于一些蒸(zheng)汽(qi)和熱(re)(re)水(shui)管(guan)(guan)(guan)(guan)道(dao)可以(yi)采用(yong)直埋的(de)布置(zhi)方式，相應(ying)的(de)管(guan)(guan)(guan)(guan)道(dao)材料(liao)(liao)可選用(yong)鋼(gang)套鋼(gang)管(guan)(guan)(guan)(guan)及(ji)管(guan)(guan)(guan)(guan)件(jian)、高密度(du)聚乙烯外護(hu)管(guan)(guan)(guan)(guan)保溫(wen)管(guan)(guan)(guan)(guan)及(ji)管(guan)(guan)(guan)(guan)件(jian)等材料(liao)(liao)。如圖4-80所示，這種材料(liao)(liao)既解(jie)決了管(guan)(guan)(guan)(guan)子(zi)熱(re)(re)膨脹問題，也解(jie)決了隔(ge)熱(re)(re)層的(de)防水(shui)等問題。詳細講述見《工業管(guan)(guan)(guan)(guan)道(dao)配管(guan)(guan)(guan)(guan)設計與工程應(ying)用(yong)》《管(guan)(guan)(guan)(guan)道(dao)器材選用(yong)與工程應(ying)用(yong)》。

  有(you)關標準規范包括：GB／T 29047《高密(mi)度聚乙(yi)烯(xi)外護管(guan)(guan)硬質(zhi)聚氨(an)酯泡沫塑(su)料預(yu)制直埋保(bao)溫(wen)(wen)(wen)管(guan)(guan)及管(guan)(guan)件(jian)》［適用于輸送介質(zhi)溫(wen)(wen)(wen)度（長期運行溫(wen)(wen)(wen)度）不高于120℃，偶然峰值溫(wen)(wen)(wen)度不高于140℃的預(yu)制直埋保(bao)溫(wen)(wen)(wen)管(guan)(guan)、保(bao)溫(wen)(wen)(wen)管(guan)(guan)件(jian)及保(bao)溫(wen)(wen)(wen)接頭］

  EN 253《用(yong)于區域供熱熱水(shui)管(guan)網一由工作鋼管(guan)、聚氨(an)酯保溫層和高密(mi)度聚乙烯外護(hu)管(guan)組(zu)成的預(yu)制直埋保溫管(guan)》；

  EN 448《用于區域供熱熱水管網一(yi)由工(gong)作鋼(gang)管、聚氨酯保溫(wen)(wen)層和(he)高密度聚乙烯(xi)外護管組成的預制(zhi)直埋保溫(wen)(wen)管件(jian)》；

  EN 489《用于(yu)區域供(gong)熱(re)熱(re)水(shui)管網一由工作鋼(gang)管、聚(ju)氨酯(zhi)保溫(wen)層和(he)高密度聚(ju)乙烯外護管組成的預制(zhi)直(zhi)埋保溫(wen)管道接頭》。

  有(you)(you)的(de)壓力(li)管道(dao)(dao)設計(ji)人(ren)員用普通的(de)隔熱(re)保(bao)溫管道(dao)(dao)直埋，會導致隔熱(re)層失效。有(you)(you)的(de)壓力(li)管道(dao)(dao)設計(ji)人(ren)員做地溝，在地溝內按地上管道(dao)(dao)布置(zhi)設計(ji)蒸汽或熱(re)水管道(dao)(dao)，不如直埋布置(zhi)設計(ji)成本更低一些(xie)。