运行管线在役焊接试验研究

运行管线在役焊接修复能很大程度上减小管道泄压停输修复所带来的经济损失,但由于管内介质的快速冷却,容易产生热影响区的氢致开裂。为了研究管内流体对焊接接头的影响,为避免氢致开裂而获得优良的焊接接头提供依据,采用模拟试验装置对16Mn在流动水冷却条件下焊接接头的微观组织和硬度进行了分析,并与空冷和静态水冷条件下的组织、硬度进行了对比。结果表明,流动水的快速冷却使焊接接头区形成了淬硬组织上贝氏体,导致其硬度值很大,易发生氢致开裂。在避免烧穿的前提下增大焊接电流能够减小硬度、减少上贝氏体,从而降低氢致开裂敏感性。

Experimental study on in-service welding of running pipelines

Repair of running pipelines by welding can reduce the economic losses of interruption of the oil and gas flow. In order to study the influence of the liquid in the pipeline on the weld joint and avoid hydrogen cracking, the microstructure and hardness of the joints of 16Mn were studied at the cooling of flowing water using the simulated experimental device. And the results were compared with the cooling of static water and air-cooling. The results show that upper bainite is formed in the joints and the hardness of the joints is high because of the fast cooling of flowing water. The joints are subject to hydrogen cracking. The increase of weld current can reduce the hardness and the content of upper bainite, and lower the sensibility of hydrogen cracking of the joints.