NRC CALLS FOP BETTER OFFSHORE PIPELINE REGULATION

Aug. 8, 1994
A National Research Council study has recommended some modest improvements in the regulation of U.S. offshore pipelines. The Interior Department's Minerals Management Service and the Transportation Department's Office of Pipeline Safety asked for the report after two fishing vessels struck pipelines that were no longer buried adequately. There are more than 20,000 miles of pipelines in U.S. waters, mostly in the Gulf of Mexico, NRC's study said "The safety record of marine pipelines

A National Research Council study has recommended some modest improvements in the regulation of U.S. offshore pipelines.

The Interior Department's Minerals Management Service and the Transportation Department's Office of Pipeline Safety asked for the report after two fishing vessels struck pipelines that were no longer buried adequately. There are more than 20,000 miles of pipelines in U.S. waters, mostly in the Gulf of Mexico,

NRC's study said "The safety record of marine pipelines is a good one, but it can be improved.

"During the late 1980s, the Gulf of Mexico OCS experienced about one reportable pipeline failure every 5 days. Most of these failures were small leaks of gas or small oil spills caused by corrosion."

NRC urged MMS to coordinate an effort by regulatory agencies to develop a common safety data base covering federal and state waters.

It said, "The focus should be on collecting, archiving, analyzing, and reporting safety data with the intent of improving design and operating regulations."

RISK MANAGEMENT

It also said safety rules should be based on sound risk analysis and cost/benefit analyses.

"Specifically, regulatory agencies should agree on a consistent risk management strategy for setting priorities about human safety criteria and about use of cost/benefit analysis for the reduction of property and environmental damage."

It said regulators should develop a zone-based risk analysis model and recommended that MMS assume enforcement of OPS marine pipeline safety rules to make better use of inspection resources and integrate enforcement.

NRC said existing pipelines should not be required to use smart pigs for external or internal corrosion detection, but new medium to large diameter lines should be designed to accommodate them.

"Pipeline operators should use a combination of leak detection methods to ensure timely detection of a broad range of leaks. Setpoint-limit control systems, where practical, should be used to provide quick detection of relatively large leaks.

"Line balance calculations should be conducted daily, where practical, to monitor for small to medium sized leaks. Periodic visual surveillance should be used to detect very small leaks and those that have gone undetected by other means."

The report said MMS should coordinate a multiagency program to set up a system under which third parties can report leaks to a single center.

NRC said offshore operators should consider installing permanent mooring systems in areas where supply and service vessels operate adjacent to fixed platforms with high densities of pipelines or flow lines or have vessels anchor in designated areas.

"To lessen the risks of damage in these congested areas, new pipelines should be installed whenever possible in well defined corridors."

BURIAL DEPTHS

Although some vessel-pipeline accidents have occurred in shallow water where pipelines no longer are adequately buried, NRC found nothing to indicate that initial burial depths are inadequate. Standard industry practices and regulations do not require periodic inspection of shallow water pipelines to ensure that they are not exposed on the seabed.

NRC recommended that operators and agencies conduct studies to determine the appropriate burial depths under various shoreline and seabed conditions using data from periodic pipeline depth of cover surveys.

And periodic depth of cover surveys should be conducted in water less than 15 ft deep according to the specific local shoreline and seabed dynamics and the passage of severe storms.

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