Sunday, November 6, 2011

Pump station plumbing; Alyeska to spend millions to reconfigure piping as safeguard against corrosion

Wesley Loy
For Petroleum News

The operator of the trans-Alaska oil pipeline is embarking on an expensive, three-year program to replace piping in several pump stations.

The work stems from a settlement Alyeska Pipeline Service Co. reached with federal regulators following a corrosion-caused oil spill in January at Pump Station 1 on the North Slope. The leak forced a lengthy shutdown of the pipeline.

Alyeska has told the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration it has completed a risk assessment of pump station piping that’s subject to corrosion and difficult to inspect. It was piping of this sort that leaked at Pump Station 1.

As a result of the assessment, Alyeska is designing plans for work at pump stations 1, 3, 4, 5 and 9.

“These designs will replace buried non-inspectable crude oil piping with piping in an above ground alignment,” says a summary document Alyeska provided at the request of Petroleum News.

Costly campaign

The piping replacement work actually consists of several major projects, each to cost “tens of millions of dollars to complete,” said Alyeska spokeswoman Michelle Egan.
Firms under existing contracts will handle part of the work, with some jobs to be put out for bid, Egan said.

The piping to be replaced is characterized as “dead leg, low and intermittent flow, and concrete encased piping,” the summary document says. Such piping can’t be excavated for inspection, or inspected internally with tools called pigs.

Alyeska has given regulators a schedule for doing the piping replacements. Pump Station 1 will see “the most complex and critical” project, Alyeska says. It will be the first station to have its below-ground crude oil piping rerouted to an above-ground configuration.

The final design for Pump Station 1 will be finished by year’s end, with construction to start in the first quarter of 2012 and conclude in the fourth quarter of 2013, the schedule shows.

Projects will follow at pump stations 3, 4, 5 and 9, with all the piping replacements to be finished by the fourth quarter of 2014.

“Each of the pump stations will have a two year construction season to complete all of the piping work,” the Alyeska summary says. “The first construction season will install civil foundations, pipe supports, trenches, and other preparatory work and the second season will install the piping and make the final tie-ins.”

Aging pipeline

Alyeska is the Anchorage-based consortium that runs the trans-Alaska pipeline on behalf of owners BP, ConocoPhillips, ExxonMobil, Chevron and Koch Industries.
The pipeline has been moving oil from Prudhoe Bay and other North Slope fields since June 20, 1977.

Federal pipeline regulators hit Alyeska with a “notice of proposed safety order” in February, following the leak inside a Pump Station 1 building basement. The leak forced a pipeline shutdown lasting about three and a half days.

The leak was described as a booster pump manifold failure. A manifold is an arrangement of piping or valves designed to control, distribute or monitor fluid flow.

The mainline, 48-inch pipe was not involved.

Alyeska retained Det Norske Veritas, a Norwegian concern specializing in risk management, to do an independent investigation of the Pump Station 1 leak.

A 6-foot section of piping, containing the location of the leak, was removed and shipped to Det Norske Veritas for metallurgical analysis, the Alyeska summary says.

In their proposed safety order, federal pipeline regulators cited “multiple conditions” on the pipeline that appeared to pose an integrity risk. The concerns centered on the pipeline’s declining oil throughput and the potential for freeze-ups and corrosion.

As part of the settlement Alyeska signed with PHMSA in August, Alyeska agreed to replace or remove hard-to-inspect oil piping.

Marine terminal involvement

“It’s important to emphasize that a lot of these piping issues can be attributed to declining flow through our systems and that many of these piping projects were already planned,” Alyeska’s Egan said.
Aside from the pipeline itself, Alyeska operates the Valdez Marine Terminal, where the line ends and where tankers pick up crude for delivery to West Coast refineries. The terminal is a sprawling, waterfront complex of tanks, pipes and piers.

The Alyeska summary says a risk assessment was done not only for pump station piping, but also for marine terminal facility piping.

The summary, however, says nothing about any planned piping replacements at the terminal.

Republished with the permission of the Petroleum News