North Slope Borough Natural Gas Line Coating Repair

Project Overview

The Nuiqsut Natural Gas Pipeline (NNGP) runs 15-miles from the Alpine Oil Field to Nuiqsut via a 3-inch diameter steel pipeline. Approximately nine miles of the NNGP are aboveground and protected against external corrosion by an extruded high-density polyethylene DzYellow Jacketdz pipe coating. A PHMSA audit identified areas of coating damage that left the pipeline out of code compliance.

The client hired another engineering firm who recommended that the pipeline be replaced at a cost of over $14 million, citing widespread UV damage and extensive coating disbondment.

The North Slope Borough (NSB) tasked Taku with conducting a peer review of that assessment. Taku conducted detailed field and laboratory testing which determined that only 4% of the coating was damaged and that there was no measurable coating UV deterioration. The coating repairs required on the existing pipeline were comparable to the weld lanes coating repairs that would have been necessary on a new pipeline installation.

Engineering Design Services

The services Taku provided on this project consisted of the following:

  • Conceptual Engineering
  • Field Testing of Coating Repair Systems
  • Civil/Structural Engineering
  • Total Install Cost Estimating (TIC)
  • Bid Package Development & Support
  • Implementation Oversight

Taku thoroughly understands coating engineering and regulatory compliance.

Taku identified coating systems and techniques for repair and developed a TIC estimate for repair. The NSB tasked Taku with the detailed design for the coatings repair system. The project design is complete and an implementation contractor has been selected.The repair of the pipeline vs replacement will save the NSB approximately $10 million. Additionally, the coatings repair versus pipeline replacement scope drastically reduces the footprint of the project. This will reduce the possibility of causing damage to the tundra.