Pig Retrieval

Hallen Construction recently undertook a challenging operation to retrieve an in-line inspection tool, commonly known as an “ILI tool” or “Smart PIG”, which became incapacitated during a National Grid gas transmission pipeline inspection.

An ILI tool is a high-tech robotic instrument that is propelled within a pipeline to perform an internal integrity inspection. This model ILI, valued at two million dollars, was remotely controlled, and fueled by several high-capacity battery cells built directly into the unit. Towards the tail-end of the inspection run, the ILI batteries became too weak to navigate a tight radius bend, thus leaving the tool stranded 27 feet deep below the ground surface. Recognizing the potential risk of disruption to their gas system, National Grid turned to Hallen for help.

Hallen assembled an elite team of our best pipeline workers to take on the task. After meticulous planning, coordination, and engineering the team successfully excavated down to the depth of the tight radius bend so it could be cut away and expose the top end of the ILI tool. Once exposed, cables were tethered to the ILI, which were then used to winch the 13-foot-long tool out of the pipeline. The tool was retrieved without incident or any physical damage to the unit. More importantly, the pipeline was reinstated and put back into service, averting any environmental or operational hazards and any disruption to National Grid’s gas supply chain.

Photos from Pig Retrieval are below