As part of normal maintenance, the operator of a natural gas pipeline system in the northeast U.S. cleaned their 42-inch pipeline with liquids. After running displacement pigs to dry the line, however, an unknown volume of liquids remained in a low point, restricting product flow.
To evacuate the pooled liquids, the operator decided to send a probe into the pipeline, with access through a hot tap.
A third-party service provider prepared to hot tap the one-inch-thick carrier pipe by attaching a 4-inch branch with reinforcement pad to strengthen the branch joint, flange, and valve assembly. When the service provider tried to drill the 4-inch tap through the valve, the pilot bit seized and broke—its remnants were left in the partially penetrated guide hole.
The operator then contracted a second service provider to complete the tap, but they were unsuccessful as well. In their attempt, the pilot bit hit what remained of the broken bit, knocking the cutter into the side of the 4-inch nozzle and damaging it. As a result, the 4-inch branch connection now also needed to be replaced.
With the time clock on their planned shutdown ticking away and two futile attempts to drill the pipeline behind them, the operator needed a fresh approach, including a way to remove the broken bit.