August 25, 2006 4:00 AM PDT
Fiber optics help keep oil spills at bay
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Approximately 2.2 million miles of oil and gas pipelines crisscross North America, and the average age of the pipes is 29 years old, according to Gary Jolly, the CEO of Fiber Optic Systems Technology (Fox-Tek), which sells systems for monitoring the rate of corrosion in beams and pipes. Recently reported corrosion problems in a BP pipeline in Alaska are really more of a symbol of the problem than an isolated incident, he said.
And what about all those historically interesting steel bridges built by the Works Projects Administration in the 1930s?
"Half the bridges in North America you wouldn't want to drive on," he said.
Founded in 2001, Fox-Tek has developed optical sensors that detect minute changes in the strain on a structure. The changes in the strain are forwarded via a fiber link to a ground station near the sensor. The data gathered is then converted mathematically into a predicted rate of corrosion.
With the data, pipeline owners can then predict how far in the future failure might become an imminent danger and schedule preventive maintenance when it's cheapest or most convenient.
"Let's say you're in Alaska or Northern Canada and it's 40 degrees below. Digging becomes problematic," he said. "We can pick up micron-level changes (in a pipe)."
Saudi Aramco has conducted trials with Fox-Tek's technology at refineries in Riyadh and Abqaiq; the Saudi oil giant will make an announcement regarding broader use of the company's products, Jolly said. CalTrans, the California agency that builds and maintains the state's roads, has also contacted Fox-Tek to take a look at the technology.
Corrosion is a chronic problem in the petroleum industry. Pipeline builders have to put 90-degree bends into pipeline to relieve stress on the pipeline caused by its own weight, as well as to let the pipeline get around natural or manmade obstacles. At elbow joints, the pipe becomes susceptible to corrosion. The outside environment and chemicals inside can also foster corrosion.
To detect problems, pipeline owners will send robots called "smart pigs" down the pipe. Checking whether an anomaly a pig has pinpointed in a section of pipe above ground is relatively simple: Workers can drive out there and examine it. But to get to an underground anomaly, pipeline owners have to dig a hole, take a look, and then cover it up until the next examination.
Two beams of light
With Fox-Tek's system, the sensors can provide regular assessments of the damage. Pipeline owners also won't have to redig holes because the sensor can be planted on the pipe on the first dig.
The system works because of the sensitivity of fiber optics. In Fox-Tek's system, the sensor, which gets stuck to an area under strain, beams light at a reflective surface, which then sends a signal back. Initially, the two beams are equal in length. Increased strain on the pipe, however, will throw off synchronization; the resulting changes then give engineers a way to gauge the progress of corrosion.
Optical sensors also tend to be fairly durable and will work in environments as hot as 300 degrees Celsius. The sensors can monitor sections of pipe (or of a building) as long as 100 meters or be tuned to probe sections only a few inches long.
The technology isn't cheap. A single sensor costs approximately $1,000 and a field station for gathering data from the sensors runs $45,000. Some of the monitoring systems installed in the Middle East get power from solar panels. But the consequences of an accident can be fairly extensive.
BP spilled 200,000 gallons of crude onto the tundra in Alaska in March, and in August the company revealed that it had found 16 weak spots due to corrosion in 12 locations. Fines, cleanup costs, repairs and the slowdown in production are expected to cost millions, according to various estimates.
"We deeply regret that it has been necessary to take this drastic action of an orderly and planned shutdown of the Prudhoe Bay oil field. On behalf of the BP Group, I apologize for the impact it is having on the nation and the state of Alaska," said Bob Malone, chairman of BP America, earlier this month in a prepared statement.
Rather than regularly run pigs down its lines in Alaska, BP relied on what's called a flow rate system, which essentially detects changes in the flow inside the pipe. (Corrosion can impede the flow). Flow rate systems can detect a 1 percent change in the flow of material going down the pipe. While that sounds low, it can translate into thousands of gallons. And crude oil is a relatively safe material.
"Think if you had 1 percent of several million cubic feet of natural gas a day leading out," Jolly said. "That's enough for a fairly big explosion in your backyard."