复合型下向焊焊接工艺及操作技术

针对纤维素焊条电弧焊在管道焊接中，单纯的下向焊热输入低，熔深较浅，难以发挥其焊接速度快、效率高的特点，提出了可发挥两种焊接方法特点的复合型下向焊技术，介绍了复合型下向焊的工艺特点、焊条选择以及对电焊机、焊接接头和坡口组对等的要求，阐述了复合型下向焊的焊接工艺及操作技术，并对经常出现的焊接缺陷制定了预防纠正措施，在实际施工中获得了很好的焊接质量，达到了优质高效的目的，为复合型下向焊焊接施工提供了可靠的技术参考。

Compound Downward Welding Process and Operation Technology

Aim at the characteristics of simplex downward welding in cellulose SMAW pipeline welding,such as low heat input and shallower penetration,and its high speed welding and high efficiency can’t be fully realized.It put forward a new kind of compound downward welding technology,which can play two welding methods,introduced process characteristics,welding electrode selection and the requirements to welding machine,joints and groove assembling,expatiated welding process and operation technology of downward welding.It also established preventive measures to the common occurred defects,and it obtained good welding quality in practical construction,this will provide reliable technical reference to compound downward welding construction.