Pipeline Integrity
The integrity, safety and efficiency of the Alliance Pipeline system began with its innovative design, where special consideration was given to the integrity of the pipeline. The main design considerations were pipe wall thickness and material properties. The 36-inch diameter mainline system was designed using heavy wall pipe 20 to 50 percent thicker than most operating pipelines and with high quality assurance standards. The metallurgical and other material properties of the Alliance line pipe considered fracture control design, since the Alliance pipeline system was designed to transport high energy natural gas at a comparatively high pressure. Full scale pipe burst tests were also conducted to validate the fracture control plan for fracture arrest.
Buried piping is protected against external corrosion by high integrity coatings such as fusion bond epoxy and cathodic protection. The gas quality standard is stringently controlled and the pipe is internally coated with an epoxy resin designed to smooth the pipe wall, leading to increased gas flow. The selection process for the coating systems was followed by extensive prequalification testing.
During the design and construction phase of the pipeline system, Alliance developed and implemented an in-house quality management program that encompassed all construction and commissioning activities, including the manufacture of pipe, coating application and testing and manufacture of components and assemblies.
Operating Pressure
Alliance Pipeline uses a Maximum Allowable Operating Pressure (MAOP) of 1,743 psi (pounds per square inch) on the Canadian portion of the mainline system. In late autumn 2006, Alliance was granted a waiver to increase the MAOP on the US portion of the mainline system to 1,935 psi. The MAOP pressure increase in the US was successfully completed in December 2007.
As a condition of the Department of Transportation (DOT) and Federal Energy Regulatory Commission (FERC) approval for the pressure increase in the US, Alliance Pipeline agreed to perform additional above-ground pipeline integrity surveys and investigative inspection work over the course of three years as well as subsequent in-line inspection (ILI) surveys on a seven-year cycle.
Baseline In-Line Inspection and Corrosion Control
Alliance Pipeline has maintained an excellent pipeline integrity record and continues to revise and enhance processes, applying the most recent in-line (ILI) inspection technology. Alliance has also exceeded regulatory requirements for ILI inspection frequency.
Click to view Alliance Pipeline’s Integrity Management Plan.