Welding onto an in-service pipeline

Rehabilitation of Pipelines Using Fiber-reinforced Polymer (FRP) Composites 

Simple guidance has been developed and is available elsewhere for preventing both burn-through and hydrogen when welding onto an in-service pipeline (Bmce, 2009). This simple guidance is summarized below. 

If the wall thickness is less than 0.250 in (6.4 mm), there may be a need to take special precautions to minimize the risk of bum-through. These precautions include minimizing the penetration of the arc into the pipe wall by using small-diameter, low-hydrogen electrodes and a procedure that hmits heat input. 

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