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Positioning module flare boom on Northstar Island a challenge
By Alan Bailey PNA Contributing Writer
When BP Exploration (Alaska) Inc.’s Northstar field production facilities arrive at Northstar Island in mid-August, contractors will install the compressor module. The positioning of this massive module and its flare boom presents one of the biggest lifting challenges of the construction project on Northstar Island.
Managed Integrity Services Inc., a subsidiary of ASCG Inc. and part of the Alaska Slope Regional Corp., has planned the August lift for Alaska Interstate Construction.
Eric Paivio, lift program manager for Managed Integrity Services Inc., talked to PNA about the difficulties of maneuvering the 200 foot flare boom on the 600 foot by 400 foot Northstar island without hitting the drilling rig and other equipment.
“We have to pretty precisely know how we’re going to lift this thing step by step … once we get this thing into a … 47 degree angle with two cranes, they’ve actually got to move the 3,500 ton compressor building to it.”
“It’s going to be a tough lift … the flare boom’s out of balance, it’s got to stay in kilter,” Jeff Smith, business development leader for Managed Integrity Services, told PNA. The lift crew will deploy two 250 ton Manitowoc 888 cranes to position the flare boom, with one crane lifting each end of the boom.
Working out how to move the flare boom up the 3 percent grade on the shore of the island has required some innovative thinking, Paivio said.
The initial plan involved hoisting the boom between two cranes and then walking the cranes up the slope. However, this plan meant positioning the cranes too close to the drilling rig and other structures on the island. Additionally, the grade seemed likely to exceed the manufacturer’s recommended capabilities of the cranes.
“We decided it wouldn’t work,” Paivio said. “At one point on the plans we (would have) wiped out the Halliburton tanks,” he said. Rolling flare boom up the grade Instead, AIC came up with a plan to roll the flare boom up the grade using Scheuerle motorized crawlers, equipment that is normally used to move buildings on the North Slope. The cranes will come into action once the boom reaches the level surface of the island.
Paivio and his team used an automated design computer program called Lift Planner“ to plan the lift and evaluate different lifting scenarios.
“The beauty of the (Lift Planner) program is that we can take these (lift) plans and look at them inside out … isometric as well as plan views — they’re extremely detailed,” Paivio said.
Using the computer program, the planning team has been able to design the Northstar lift step by step, measuring clearances between objects and calculating the required crane loads.
The planners have also used the computer system to generate a video simulation of the complete lift. Everyone involved in the lift can view the video to gain a clear understanding of the lift process.
“When we’ve done this (in the past) a lot of folks have said it’s like déjà vu — we’ve seen this before, when it actually happens,” Paivio said.
However, no one wants to take the slightest chance of a problem. The construction team has already done a trial installation of the flare boom in Anchorage. It was “performed as planned and without any problems,” Smith said.
The compressor module was built by VECO in Anchorage. Mustang Engineering of Houston, Texas, fabricated the flare boom and barged it to Anchorage.
Parsons will be supervising the lift at Northstar Island.
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