The hydrocarbon transportation and distribution industry benefits greatly from in-service welding by reducing operational disruption costs. In-service welding is used to repair internal and external defects, such as leaks, using weld deposition or sleeves (Type A or B) and hot tapping operations. If in-service welding is not possible, then sections of a pipeline have to be sealed and degassed prior to welding, and then re-purged prior to reinstatement. Since there are high gas losses and methane is a greenhouse gas, these are costly, wasteful, and environmentally destructive practices. TransCanada Pipelines Ltd. has estimated that, relative to a cold connection, a hot-tap avoids gross revenue losses of approximately 1 M$ Canadian per hot-tap.

The main objective of this work is to provide an in-service welding procedure that allows operators to operate under more severe conditions (in terms of flow rate and pressure) and at thinner thicknesses than the minimum thickness recommended in the standards, while minimizing the risk of burn-through and hydrogen embrittlement.