| Pipeline Maintenance
Digs Prudhoe Bay, on the northern coast of Alaska, is the
severely cold, desolate location of TransAlaska pipeline’s Pump Station #1. Winter
temperatures at Prudhoe Bay dip as low as -56° F, with wind chills approaching -100° F. Frost depths reach more than 2000 feet in some areas. Alyeska Pipeline
Services owns and operates the 48-inch diameter, 800-mile pipeline, which carries more
than 1.5 million barrels of crude oil from Prudhoe Bay to Valdez daily. At $16.90 per
barrel, the pipeline currently delivers $25 million worth of oil each day. With the
pipeline generating this level of revenue, downtime is unacceptable.
To ensure safe and efficient maintenance of the pipeline, Alyeska
contracts both Houston/NANA and Alaska Petroleum Contractors, Inc. (APC) to perform more
than 200 maintenance digs a year for the northern half of the pipeline. One would assume
that these digs would be performed in the summer, when weather conditions are more
favorable for outdoor work – this is not the case. "Because we work on the
tundra," said Kenny Broker, heavy equipment coordinator for Houston/NANA, "
environmental officials are very strict about work permits. Basically all pipeline
maintenance has to be done in the winter, when the tundra’s surface is frozen solid,
so we don’t leave any footprints or tracks."
According to Bob Bumbaugh, assistant superintendent for APC, both air
and steam heaters have been used to thaw the ground, but with limited success.
"We’ve used air heaters up here, but it requires building an enclosure to direct
the heat into the ground," Bumbaugh said. "[Using air heaters], it’s
difficult to contain the heat with the high winds and extreme temperatures." Steam
heaters have also left much to be desired. "The problem with steamers is that the
ground up here is already very wet, and the steamers just pump a lot more moisture into
the ground, leaving a big muddy mess," Broker said. "Worker safety is also a
concern with steam heaters because there is a danger of getting burned." Thus, both
Broker and Bumbaugh were anxious to find a safe, effective method of ground thawing to
maintain the massive pipeline.
Early this winter, the ground thawing solution presented itself. Yukon
Equipment, a Ground Heater dealer with 3 locations throughout Alaska, contacted Kenny
Broker proposing APC try the Ground Heater for thawing along the pipeline. Broker
answered, "If they work in these severe conditions, we would be very interested in
renting or purchasing some."
Yukon Equipment confidently accepted Broker’s challenge to
"tame the tundra." Loading up two model E3000 Ground Heaters, representatives
from Yukon Equipment traveled more than 400 miles to the frozen tundra of Prudhoe Bay.
"We chose a gas line dig at Pump Station #1 for the demo,"
Broker said. "Since the natural gas lines power the pump station turbines, we have to
make sure the lines are intact and not corroding." The gas line was buried about 6
feet deep and the dig required thawing an 800-square foot excavation area. The ground
temperature at the dig location measured -23° F.
|
Kenny Broker
Heavy Equipment
Coordinator,
Houston/NANA
Bob Bumbaugh
Assistant Superintendent,
Alyeska Petroleum Contractors, Inc.
|
 After 40 hours of run time, the E3000
had thawed to a depth of 40 inches. Within 115 hours, roughly 5 days, the required thawing
depth of 6 feet was achieved. Yukon Equipment proved the Ground Heater could effectively
thaw ground – even on the tundra. "We’ve continued to use the Ground Heater
with great success," Bumbaugh said. "It’s a more effective way of directing
heat into the ground. It drives the heat and moisture way down, thawing faster than other
methods." Additionally, Ground Heaters offer a safer method of thawing. "With
the way the Ground Heaters work, there’s no danger of being burned as with steam
heaters," Bumbaugh said. "And it’s environmentally safe!"
Bumbaugh also found the simplicity of the Ground Heater attractive.
"I use fewer man-hours in the field because it’s so easy to set up – two or
three guys can set it up in less than an hour, and it doesn’t have to be constantly
monitored," Bumbaugh said. "After setup, we just let its heat soak in for a week
or two, and then come out to do our digs. With a steamer, we would need a whole crew out
there, all day and night." The Ground Heater not only saves on manpower and expenses,
but also keeps personnel out of these dangerous weather conditions. "Anything that
can reduce our time spent in the field under these arctic conditions is a big help,"
Bumbaugh said.
Since the Prudhoe Bay test was successful, Houston/NANA has now added
the Ground Heaters to its extensive equipment fleet. "The Ground Heaters worked very
well and solved a lot of our ground-thawing problems," Broker said. "The Ground
Heaters will be seeing a lot of use on the pipeline – no doubt about it."
Go to Ground Heaters Surface
and Air Heater Products Page
Go Back to the Job
Studies Page
|
|
