管道工程中常用(yong)的有色金屬(Non-ferrous Metal)有銅、鋁、鉛和(he)鋅等(deng)。
1. 銅(Copper)
銅(tong)(tong)又(you)分純銅(tong)(tong)(俗(su)稱(cheng)紫銅(tong)(tong))、黃(huang)銅(tong)(tong)和(he)青銅(tong)(tong)等。有關銅(tong)(tong)管(guan)的標準(zhun)規范包括 ASTM B42、ASTM B43、ASTM B315、ASTM B466、ASTM B467,有關銅(tong)(tong)管(guan)件的標準(zhun)規范有ASMEB16.24、ASME B16.22、ASME B16.15、ASME B16.18等。
a. 純銅(Copper)
純(chun)(chun)銅(tong)(tong)呈紫紅色,有(you)良好的導(dao)電性、導(dao)熱性和(he)耐(nai)大(da)氣(qi)腐蝕性,熔點為(wei)1083℃。在(zai)管(guan)(guan)道工程中常(chang)用純(chun)(chun)銅(tong)(tong)制成鋼管(guan)(guan)和(he)法蘭(lan)墊片(pian)。因純(chun)(chun)銅(tong)(tong)硬度(du)較低,退火后變(bian)得更(geng)柔軟,故常(chang)用來(lai)制作高壓(ya)管(guan)(guan)道中 的法蘭(lan)墊片(pian)。純(chun)(chun)銅(tong)(tong)管(guan)(guan)的低溫性能比鋼材好,故純(chun)(chun)銅(tong)(tong)管(guan)(guan)常(chang)用于空分(fen)設備管(guan)(guan)道、冷凍管(guan)(guan)道和(he)儀表管(guan)(guan)道。純(chun)(chun)銅(tong)(tong)的高溫性能差,在(zai)120℃以(yi)下,允(yun)許抗(kang)拉強度(du)為(wei)29.43MPa。溫度(du)若再升高,其機械強度(du)則(ze)急(ji)劇(ju)下降,當(dang)(dang)溫度(du)上升至250℃時,其允(yun)許抗(kang)拉強度(du)只(zhi)相當(dang)(dang)于常(chang)溫時的2/3,已(yi)不宜(yi)在(zai)壓(ya)力(li)下使用。
常用的(de)純銅牌號(hao)為T2、T3、T4,雜質含(han)量T2最(zui)少,T4最(zui)多。
b. 黃銅(Brass)
黃銅(tong)是銅(tong)和鋅的(de)合(he)金,其(qi)機械強(qiang)(qiang)度(du)高,有較(jiao)好的(de)耐腐蝕性(xing)和澆鑄性(xing),可用(yong)(yong)來制作(zuo)管子(zi)、管件和閥門(men)等。化工上常用(yong)(yong)的(de)有H80、H68、H62(“H”是黃銅(tong)代號,后(hou)邊的(de)數(shu)字表示合(he)金中銅(tong)的(de)平均含量)。H80比H68塑性(xing)好。進行強(qiang)(qiang)度(du)計算時,在120℃以下(xia)(xia),黃銅(tong)允許抗(kang)拉(la)強(qiang)(qiang)度(du)為(wei)29.43MPa。隨著溫(wen)(wen)度(du)升高,其(qi)強(qiang)(qiang)度(du)則急劇(ju)下(xia)(xia)降,當溫(wen)(wen)度(du)未超過(guo)225℃時,黃銅(tong)閥件可用(yong)(yong)在壓力不超過(guo)1.6MPa的(de)管道(dao)中。
c. 青銅(Bronze)
青(qing)(qing)(qing)銅(tong)(tong)是(shi)銅(tong)(tong)和(he)錫的合金,又稱錫青(qing)(qing)(qing)銅(tong)(tong)。由(you)于錫的價格較高,故制造(zao)青(qing)(qing)(qing)銅(tong)(tong)也(ye)常(chang)用其(qi)他元素代替,因而又有無錫青(qing)(qing)(qing)銅(tong)(tong),如(ru)鋁青(qing)(qing)(qing)銅(tong)(tong)、鉛青(qing)(qing)(qing)銅(tong)(tong)、硅青(qing)(qing)(qing)銅(tong)(tong)等。青(qing)(qing)(qing)銅(tong)(tong)通常(chang)由(you)澆鑄而成,其(qi)強度(du)、硬度(du)及(ji)耐(nai)腐蝕性都比黃銅(tong)(tong)好。青(qing)(qing)(qing)銅(tong)(tong)常(chang)用于制造(zao)蝸輪、齒輪、輪,以(yi)及(ji)管道工程中的閥件和(he)管件等。
2. 鋁(lv)(Aluminum)
鋁的(de)(de)(de)熔點為(wei)527℃,它(ta)具有良(liang)好的(de)(de)(de)導熱性(xing)和導電(dian)性(xing),強(qiang)度(du)和硬度(du)較低,可塑性(xing)好。鋁容易氧(yang)化,在空氣中(zhong),鋁的(de)(de)(de)表面能(neng)形(xing)成一層(ceng)極薄(bo)的(de)(de)(de)氧(yang)化鋁保護膜,防止繼(ji)續氧(yang)化。鋁合(he)金薄(bo)板常作為(wei)壓力(li)管道絕熱工(gong)程的(de)(de)(de)管子、塔、罐、換熱器(qi)、閥門、法蘭以及(ji)其他(ta)平壁設備保護層(ceng)材料。
純(chun)鋁(lv)(lv)的(de)(de)強度(du)和硬(ying)度(du)雖(sui)然很低,但(dan)若加(jia)入其他元素可(ke)以(yi)提高(gao)(gao)。鋁(lv)(lv)合(he)金分為(wei)鑄造鋁(lv)(lv)合(he)金和可(ke)壓迫變(bian)形的(de)(de)鋁(lv)(lv)合(he)金兩(liang)大類(lei)。管道工程中,常用(yong)L2和L3牌號的(de)(de)鋁(lv)(lv)管輸送(song)硝酸和醋酸等,但(dan)是鋁(lv)(lv)不能抵抗堿(jian)性腐蝕。當(dang)溫度(du)高(gao)(gao)于150℃時,鋁(lv)(lv)管不宜用(yong)于壓力(li)管道。鋁(lv)(lv)和鋁(lv)(lv)合(he)金管的(de)(de)標(biao)準規范(fan)有(you)ASTM B241、ASTM B26、ASTM B108、ASTM B209、ASTM B210、ASTM B211、ASTM
B221、ASTMI B234、ASTM B247 以及 ASME B31.3的“附(fu)錄L-鋁(lv)合(he)金管法(fa)蘭”。
3. 鉛(qian)(Lead)
鉛(qian)(qian)(qian)是(shi)一種(zhong)暗灰色的(de)金屬,熔(rong)點為(wei)(wei)327℃,它(ta)(ta)有(you)很好(hao)的(de)耐腐蝕性能,常用來制(zhi)(zhi)作硫(liu)酸(suan)設(she)備(bei)和管(guan)道襯里。鉛(qian)(qian)(qian)質軟,可塑性好(hao),管(guan)道工(gong)程中(zhong)常用鉛(qian)(qian)(qian)管(guan)。在(zai)安裝鑄鐵(tie)管(guan)承插(cha)口時,常用鉛(qian)(qian)(qian)作為(wei)(wei)接(jie)口填(tian)塞材料,以牌(pai)號(hao)為(wei)(wei)Pb-6的(de)鉛(qian)(qian)(qian)較(jiao)適宜。硬鉛(qian)(qian)(qian)是(shi)鉛(qian)(qian)(qian)和銻的(de)合金,它(ta)(ta)的(de)抗腐蝕性略低于(yu)純鉛(qian)(qian)(qian),但機(ji)械(xie)強度較(jiao)高,常用于(yu)制(zhi)(zhi)造耐酸(suan)設(she)備(bei)。鉛(qian)(qian)(qian)蒸氣有(you)毒(du),故熔(rong)化鉛(qian)(qian)(qian)時,要防止燙傷和鉛(qian)(qian)(qian)中(zhong)毒(du)。在(zai)化工(gong)行(xing)業中(zhong),鉛(qian)(qian)(qian)主(zhu)要用在(zai)處理硫(liu)酸(suan)的(de)設(she)備(bei)上。Pb-4用于(yu)設(she)備(bei)內襯,Pb-6用于(yu)管(guan)道接(jie)頭,硬鉛(qian)(qian)(qian)可制(zhi)(zhi)造硫(liu)酸(suan)工(gong)業用的(de)泵(beng)、閥(fa)門、管(guan)道等(deng)。
4. 鋅(xin)(Zinc)
鋅(xin)(xin)呈淺灰色(se),熔點(dian)為419℃,它有(you)較(jiao)好的(de)(de)耐(nai)腐(fu)蝕性(xing)(xing)和力(li)學性(xing)(xing)能。有(you)些鋼管和管件為增強耐(nai)腐(fu)蝕性(xing)(xing)能,常在表(biao)面鍍(du)一層鋅(xin)(xin),如室內給水工程中常用(yong)的(de)(de)鍍(du)鋅(xin)(xin)管。