20#無縫管的(de)20是指含碳量為(wei)0.2%，屬于低(di)(di)碳鋼。鋼中可分為(wei)低(di)(di)碳鋼、中碳鋼和(he)高碳鋼。

碳(tan)含量：低碳(tan)鋼(gang)一(yi)般小(xiao)于0.25%；中碳(tan)鋼(gang)一(yi)般在0.25～0.60%之間；高(gao)碳(tan)鋼(gang)一(yi)般大(da)于0.60%。

20#無縫管就是我們平常所說的A3無縫管、碳素普通無縫管、美標A106無縫管

20#無縫管是用(yong)鋼(gang)錠或(huo)實(shi)心(xin)管(guan)(guan)坯經穿孔制成毛管(guan)(guan)，然后經熱軋、冷(leng)軋或(huo)冷(leng)撥制成。20#無縫管(guan)(guan)在我(wo)國鋼(gang)管(guan)(guan)業中具有重要的(de)地位。

20#無縫管分熱軋和冷軋（撥(bo)）無縫管兩類(lei)。

20#無縫管常(chang)用標準

1、結(jie)構用無縫管：GB/T8162-2008

2、輸送流體用無縫管：GB/T8163-2008

3、冷(leng)拔或冷(leng)軋精密(mi)無縫管：GB/T3639-2009

據(ju)不完全統計(ji)，我國現有20#無縫(feng)管(guan)生產(chan)企業約6500多(duo)(duo)家，無縫(feng)管(guan)機組約12057多(duo)(duo)套，年(nian)產(chan)能力約2450多(duo)(duo)萬噸(dun)。從口徑看，<φ76的(de)，占(zhan)35%，<φ159-650的(de)，占(zhan)25%。從品種(zhong)看，一般用途管(guan)1190萬噸(dun)，占(zhan)54%；石油管(guan)76萬噸(dun)，占(zhan)5.7%；液(ye)壓支柱、精密管(guan)15萬噸(dun)，占(zhan)4.3%；不銹管(guan)、軸承(cheng)管(guan)、汽車管(guan)共(gong)5萬噸(dun)，占(zhan)1.4%。

軋制無縫管的(de)原料是(shi)圓管(guan)(guan)(guan)(guan)坯，圓管(guan)(guan)(guan)(guan)胚(pei)要經(jing)過(guo)切割機的(de)切割加工成(cheng)長度約為(wei)(wei)1米的(de)坯料，并(bing)經(jing)傳送(song)(song)(song)帶送(song)(song)(song)到熔(rong)爐(lu)(lu)內(nei)加熱。鋼(gang)(gang)坯被(bei)送(song)(song)(song)入熔(rong)爐(lu)(lu)內(nei)加熱，溫度大(da)約為(wei)(wei)1200攝氏度。燃料為(wei)(wei)氫氣或乙(yi)炔(gui)。爐(lu)(lu)內(nei)溫度控制(zhi)是(shi)關(guan)鍵性的(de)問(wen)題.圓管(guan)(guan)(guan)(guan)坯出(chu)爐(lu)(lu)后要經(jing)過(guo)壓力穿(chuan)孔(kong)機進(jin)行穿(chuan)空。一般較常見的(de)穿(chuan)孔(kong)機是(shi)錐(zhui)形輥(gun)穿(chuan)孔(kong)機，這種(zhong)穿(chuan)孔(kong)機生產(chan)效率高，產(chan)品質(zhi)量(liang)好(hao)，穿(chuan)孔(kong)擴徑(jing)(jing)量(liang)大(da)，可穿(chuan)多種(zhong)鋼(gang)(gang)種(zhong)。穿(chuan)孔(kong)后，圓管(guan)(guan)(guan)(guan)坯就(jiu)先后被(bei)三輥(gun)斜軋、連軋或擠壓。擠壓后要脫管(guan)(guan)(guan)(guan)定徑(jing)(jing)。定徑(jing)(jing)機通過(guo)錐(zhui)形鉆(zhan)頭高速旋轉入鋼(gang)(gang)胚(pei)打孔(kong)，形成(cheng)鋼(gang)(gang)管(guan)(guan)(guan)(guan)。鋼(gang)(gang)管(guan)(guan)(guan)(guan)內(nei)徑(jing)(jing)由(you)定徑(jing)(jing)機鉆(zhan)頭的(de)外徑(jing)(jing)長度來(lai)確定。鋼(gang)(gang)管(guan)(guan)(guan)(guan)經(jing)定徑(jing)(jing)后，進(jin)入冷(leng)(leng)卻塔中，通過(guo)噴水冷(leng)(leng)卻，鋼(gang)(gang)管(guan)(guan)(guan)(guan)經(jing)冷(leng)(leng)卻后，就(jiu)要被(bei)矯直(zhi)。鋼(gang)(gang)管(guan)(guan)(guan)(guan)經(jing)矯直(zhi)后由(you)傳送(song)(song)(song)帶送(song)(song)(song)至金屬探傷(shang)機（或水壓實驗）進(jin)行內(nei)部探傷(shang)。若鋼(gang)(gang)管(guan)(guan)(guan)(guan)內(nei)部有裂紋(wen)，氣泡等(deng)問(wen)題，將被(bei)探測出(chu)。鋼(gang)(gang)管(guan)(guan)(guan)(guan)質(zhi)檢后還(huan)要通過(guo)嚴格的(de)手(shou)工挑選(xuan)。鋼(gang)(gang)管(guan)(guan)(guan)(guan)質(zhi)檢后，用油漆(qi)噴上編號、規格、生產(chan)批號等(deng)。并(bing)由(you)吊車吊入倉庫中。