Reversing oil and natural gas pipelines or switching the product they're carrying can have a "significant impact" on the line's safety and integrity—and "may not be advisable" in some cases, federal regulators told pipeline companies in a recent advisory.
The alert is the first time the Pipeline and Hazardous Materials Safety Administration has officially cautioned the industry about potential safety threats from restarting, reversing or reworking pipelines to handle Canadian tar sands oil and the surge in U.S. oil and natural gas supplies. If not handled properly, those changes can increase the risk of pipeline leaks and ruptures, the Sept. 12 notice said.
PHMSA said the advisory was triggered in part by last year's oil spills involving two reversed pipelines, ExxonMobil's Pegasus tar sands line in Arkansas and the Tesoro Logistics line in North Dakota. Those accidents, as well as "other information PHMSA has become aware of" led the agency to issue the alert, the bulletin said.
While the notice doesn't include new regulations, it clarifies which tests, precautions and adjustments it expects companies to undertake before they make such fundamental changes to a fossil fuels pipeline. PHMSA said pipeline companies should consider conducting a water pressure test, known as a hydrostatic pressure test, especially in pipelines with previous failures or a history of certain kinds of cracking or corrosion.
The guidance is a sign that the agency believes its rules are being overlooked, misinterpreted, circumvented or ignored, according to Richard Kuprewicz, a pipeline safety consultant who has worked on the Pegasus case and others.