大號地熱管基本上根據設計(ji)和客戶的(de)要求(qiu)一般(ban)選用(yong)無(wu)縫鋼(gang)管(guan)(guan)(guan)(guan)(guan)、螺旋鋼(gang)管(guan)(guan)(guan)(guan)(guan)和直縫鋼(gang)管(guan)(guan)(guan)(guan)(guan)。鋼(gang)管(guan)(guan)(guan)(guan)(guan)表(biao)面(mian)經過先進的(de)拋丸(wan)除銹(xiu)工(gong)藝處理后，鋼(gang)管(guan)(guan)(guan)(guan)(guan)除銹(xiu)等級可達GB8923-1988標準中的(de)Sa2級，表(biao)面(mian)粗糙度可達GB6060.5-88標準中R=12.5微米。用(yong)高壓發(fa)泡(pao)機在鋼(gang)管(guan)(guan)(guan)(guan)(guan)與(yu)外護層之(zhi)間形成(cheng)的(de)空腔中一次性(xing)注入硬(ying)質聚氨酯泡(pao)沫塑(su)料(liao)原液(ye)而成(cheng)，即俗(su)稱的(de)管(guan)(guan)(guan)(guan)(guan)中管(guan)(guan)(guan)(guan)(guan)發(fa)泡(pao)。預制成(cheng)一定(ding)壁厚的(de)黑(hei)色(se)或黃色(se)聚乙烯(xi)塑(su)料(liao)管(guan)(guan)(guan)(guan)(guan)材。其作用(yong)一是(shi)保護聚氨酯保溫層免(mian)遭機械硬(ying)物破(po)壞，二(er)是(shi)防腐、防水(shui)。