The Alaska LNG Project pipeline is being designed to carry natural gas from the North Slope to a proposed natural gas liquefaction facility in Nikiski, Alaska. The majority of the proposed pipeline will be buried, except where it crosses ecologically sensitive areas and will be routed above ground. Unlike oil, natural gas flows normally at below freezing temperatures and needs to be kept cool in the pipeline.
The current design basis is for an 806 mile, 42” diameter pipeline with up to eight compressor stations along the line. The pipeline has a capacity of 3.3 billion cubic feet of natural gas per day. The draft route continues to be amended based on input from communities along the line and input from regulatory agencies.
CLICK HERE to view our interactive map. Please note that the proposed route is preliminary in nature and subject to change.
Natural gas pipeline safety: from design to delivery
While the specific design of the proposed Alaska LNG project pipeline continues to evolve, pipelines in the United States follow stringent design, construction, and operations requirements.
The United State Department of Transportation (USDOT) is mandated to provide pipeline safety under Title 49, U.S.C. Chapter 601. The majority of natural gas pipelines in the United States are buried.
During construction, welded pipe joints are designed and installed to be stronger than the pipe itself. All critical welds must pass visual and other nondestructive tests before pipeline operates
Before operations, the pipeline is tested and pressurized to a level that far exceeds the stress the pipeline will ever operate under. This procedure ensures the strength and integrity of pipeline before it is placed into the active service of transporting natural gas.
Protection Against Corrosion:
The pipeline is covered externally with a protective coating. Then, cathodic protection is used by applying a slight electrical current to the buried pipeline to help prevent corrosion. The pipeline coating prevents the flow of electrons to the pipe’s surroundings, interrupting the small electric charge and preventing impacts on the surrounding ecology.
Before operation, all systems for providing power, communication, gas compression, transmission, and monitoring are tested and calibrated to ensure they work together safely and efficiently. Tests are conducted on all electrical, instrumentation, communications, and mechanical and computer equipment
Valves and meter stations that control and measure the flow of gas through the pipeline are also tested.
Isolation valves are installed in key locations throughout the pipeline system. The valves allow operators to control or isolate individual pipeline segments within the systems during maintenance or emergency periods.
Periodic inspections of the pipeline help detect potential problems before they become safety concerns.
Inspections use special tools that are pushed through the pipeline to collect data on pipeline location, wall thicknesses, corrosion, and stress and strain. Inspections are conducted in accordance with strict safety regulations prescribed by the U.S. Department of Transportation.