對開(kai)三通主要(yao)用于(yu)(yu)帶(dai)壓(ya)不停(ting)輸(shu)開(kai)孔(kong)(kong)(kong)(kong)（hot tap）。帶(dai)壓(ya)不停(ting)輸(shu)開(kai)孔(kong)(kong)(kong)(kong)是(shi)在(zai)不停(ting)產情況(kuang)下進行開(kai)孔(kong)(kong)(kong)(kong)接點(dian)，適用于(yu)(yu)除氧氣以外(wai)的(de)任何介(jie)質(zhi)以及不同直徑的(de)各類管(guan)道。開(kai)孔(kong)(kong)(kong)(kong)機(ji)在(zai)開(kai)孔(kong)(kong)(kong)(kong)過(guo)程中(zhong)是(shi)在(zai)完全封(feng)(feng)閉的(de)空腔內進行的(de)，刀具切削過(guo)程與空氣隔絕，無(wu)著(zhu)火、爆炸的(de)可(ke)(ke)能性(xing)。由(you)于(yu)(yu)封(feng)(feng)閉開(kai)孔(kong)(kong)(kong)(kong)、無(wu)泄漏，有毒有害介(jie)質(zhi)不能排(pai)放到(dao)大氣中(zhong)，因此(ci)對環境無(wu)污染。管(guan)道不停(ting)輸(shu)帶(dai)壓(ya)開(kai)孔(kong)(kong)(kong)(kong)、封(feng)(feng)堵技術可(ke)(ke)避(bi)免作業風險(xian)，提高安全性(xing)，使維修既(ji)迅(xun)速又經濟可(ke)(ke)靠。此(ci)技術先進，設備(bei)操作簡單，與停(ting)產開(kai)孔(kong)(kong)(kong)(kong)作業相比，其(qi)經濟效(xiao)益和(he)社會效(xiao)益顯著(zhu)。在(zai)石(shi)油、天然氣管(guan)道及熱力管(guan)線上均可(ke)(ke)帶(dai)壓(ya)開(kai)孔(kong)(kong)(kong)(kong)。典型(xing)對開(kai)三通見圖4.6.23。

  對開(kai)三通有關標準規(gui)范：API 2201《Safe Hot Tapping Practices in the Petroleum ＆Petro-chemical Industries》；SY／T 6554《石油工業(ye)帶壓開(kai)孔作(zuo)業(ye)安全規(gui)程》。