螺旋焊管設備將(jiang)帶(dai)鋼送(song)入焊(han)管機組，經多道軋輥滾(gun)壓(ya)(ya)，帶(dai)鋼逐(zhu)漸卷(juan)起，形(xing)(xing)(xing)成(cheng)(cheng)有開口(kou)間(jian)隙的(de)圓形(xing)(xing)(xing)管坯，調整擠壓(ya)(ya)輥的(de)壓(ya)(ya)下量，使焊(han)縫(feng)(feng)間(jian)隙控(kong)制在1~3mm，并使焊(han)口(kou)兩(liang)(liang)端齊(qi)平。如(ru)間(jian)隙過大，則(ze)造(zao)成(cheng)(cheng)鄰近效應減少，渦(wo)流(liu)熱量不足(zu)，焊(han)縫(feng)(feng)晶間(jian)接(jie)(jie)合不良而(er)產生未熔合或(huo)開裂；如(ru)間(jian)隙過小則(ze)造(zao)成(cheng)(cheng)鄰近效應增(zeng)大，焊(han)接(jie)(jie)熱量過大，造(zao)成(cheng)(cheng)焊(han)縫(feng)(feng)燒(shao)損(sun)；或(huo)者焊(han)縫(feng)(feng)經擠壓(ya)(ya)、滾(gun)壓(ya)(ya)后(hou)形(xing)(xing)(xing)成(cheng)(cheng)深坑(keng)，影(ying)響焊(han)縫(feng)(feng)表面(mian)質(zhi)量。將(jiang)管坯的(de)兩(liang)(liang)個(ge)邊緣加熱到(dao)焊(han)接(jie)(jie)溫度后(hou)，在擠壓(ya)(ya)輥的(de)擠壓(ya)(ya)下，形(xing)(xing)(xing)成(cheng)(cheng)共同(tong)的(de)金屬晶粒互相滲透、結晶，形(xing)(xing)(xing)成(cheng)(cheng)牢固的(de)焊(han)縫(feng)(feng)。