對于一些蒸(zheng)汽和熱水管(guan)(guan)(guan)(guan)(guan)道(dao)(dao)可(ke)以(yi)采(cai)用(yong)直埋的(de)布置方式，相應(ying)的(de)管(guan)(guan)(guan)(guan)(guan)道(dao)(dao)材(cai)料可(ke)選(xuan)用(yong)鋼套鋼管(guan)(guan)(guan)(guan)(guan)及(ji)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)、高(gao)密度聚乙(yi)烯外(wai)護管(guan)(guan)(guan)(guan)(guan)保溫管(guan)(guan)(guan)(guan)(guan)及(ji)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)等材(cai)料。如圖4-80所示(shi)，這種材(cai)料既(ji)解決了管(guan)(guan)(guan)(guan)(guan)子熱膨脹問題(ti)，也解決了隔(ge)熱層的(de)防(fang)水等問題(ti)。詳細講述見《工(gong)業管(guan)(guan)(guan)(guan)(guan)道(dao)(dao)配管(guan)(guan)(guan)(guan)(guan)設計與(yu)(yu)工(gong)程應(ying)用(yong)》《管(guan)(guan)(guan)(guan)(guan)道(dao)(dao)器材(cai)選(xuan)用(yong)與(yu)(yu)工(gong)程應(ying)用(yong)》。

  有關(guan)標(biao)準(zhun)規(gui)范包括：GB／T 29047《高(gao)(gao)密度(du)聚乙(yi)烯外護管(guan)硬質聚氨酯泡沫塑(su)料預制直埋(mai)保(bao)溫(wen)(wen)(wen)(wen)管(guan)及管(guan)件》［適用(yong)于輸送介質溫(wen)(wen)(wen)(wen)度(du)（長期運行溫(wen)(wen)(wen)(wen)度(du)）不(bu)高(gao)(gao)于120℃，偶然峰值溫(wen)(wen)(wen)(wen)度(du)不(bu)高(gao)(gao)于140℃的預制直埋(mai)保(bao)溫(wen)(wen)(wen)(wen)管(guan)、保(bao)溫(wen)(wen)(wen)(wen)管(guan)件及保(bao)溫(wen)(wen)(wen)(wen)接(jie)頭］

  EN 253《用(yong)于區域供熱熱水管(guan)(guan)網一由工(gong)作鋼管(guan)(guan)、聚(ju)氨酯保溫(wen)層(ceng)和高密度聚(ju)乙烯外護管(guan)(guan)組成的預(yu)制直埋(mai)保溫(wen)管(guan)(guan)》；

  EN 448《用于區域供熱熱水管(guan)網一(yi)由工作(zuo)鋼管(guan)、聚氨酯保溫(wen)層和高密度聚乙烯外護管(guan)組(zu)成(cheng)的預制直埋保溫(wen)管(guan)件》；

  EN 489《用(yong)于區域供熱熱水(shui)管網一由(you)工(gong)作鋼(gang)管、聚(ju)氨酯保溫層(ceng)和高密(mi)度聚(ju)乙(yi)烯外護管組成的預制直埋保溫管道接(jie)頭》。

  有(you)的壓力管(guan)(guan)(guan)道設計人員用普通的隔熱(re)(re)保溫管(guan)(guan)(guan)道直埋(mai)，會導致(zhi)隔熱(re)(re)層失效。有(you)的壓力管(guan)(guan)(guan)道設計人員做地溝(gou)，在地溝(gou)內(nei)按地上管(guan)(guan)(guan)道布置(zhi)設計蒸汽或熱(re)(re)水管(guan)(guan)(guan)道，不如直埋(mai)布置(zhi)設計成本更(geng)低(di)一些。