IsoPurge™ Used to Tie In HDD under Interstate

Client request

The Department of Transportation decided to relocate a bend in an Interstate that had frequent fatalities. This required a pipeline crossing to be re-routed using an HDD to allow for the new highway.

The best solution

The pipeline company employed the IsoTool to perform an IsoPurge, to accomplish product evacuation and isolation simultaneously. A conventional purge would have required displacing 28 miles of crude, and required additional downtime.

Plan and deliver

A nitrogen containment pig was launched ahead of the IsoTool in the event some N2 got by. Due to the weight of the tool, and a potentially insufficient nitrogen injection pressure, the IsoTool did allow some bypass. To solve this problem the containment pig was parked DS of the tie in and a DS valve was closed. A sealing pig was launched and pumped to the IsoTool. All the nitrogen DS of the IsoTool was vented at the tie in location and the tool was brought into the final parking position and set.

Service completion

The IsoTool held 150psi of pressure for 21 hours while the line was vented and the tie in occurred. A fill pig was launched and tracked to the tie in. The IsoTool was unset and the pigs were tracked 135 miles to trap.