UAA builds tool to accelerate corrosion and test mitigations to better understand pipeline longevity

by Kathleen McCoy  |   

It's no understatement to say Alaska has invested in oil. Private funds built an 800-mile trans-Alaska oil pipeline, TAPS, that zigzags across the state carrying oil from the North Slope to export through the Port of Valdez. It is an engineering feat of grand dimensions and, for most of this young state's life, its true financial backbone.

The many gathering pipelines along the North Slope that lead to TAPS exist under extreme and harsh conditions. If you've ever seen the damage that wet road conditions can have on a car - think rust and corrosion gobbling up metal fenders - then you can understand how much a North Slope oil field operator worries.

As the years of use add up, metal corrosion along the outside of a pipeline could lead to an oil spill. A key factor is that some exterior areas of insulated pipes that get wet don't dry out. It happens most frequently at the weld packs, where pipe segments connect, and where foam insulation to keep the pipes warm was applied in the field. Water seems to get to the pipe through the insulation. The gathering pipeline has these segment connections every 80 feet, so monitoring is a huge task.

Mechanical engineering undergraduate Keir Johnson, right, and his faculty supervisor, Professor Matt Cullin, left, photographed in the Parrish Bridge. Cullin and Johnson are exploring methods of reducing corrosion on the insulated piping that Alaska's petroleum industry relies on. (Photo by James Evans / University of Alaska Anchorage)

Step in, UAA mechanical engineering professor Matt Cullin and an undergraduate research assistant, Keir Johnson. Cullin is a corrosion expert. He currently directs the BP Asset Integrity and Corrosion Lab at UAA. And he also won a 2016-2017 ConocoPhillips Arctic Science and Engineering Endowment Award for $152,000, based on the idea that he and his students could build a tool capable of simulating and accelerating conditions that cause corrosion under insulation.

Cullin: "The Alaska corrosion engineers I talk to refer to CUI (corrosion under insulation) as a field-threatening damage mechanism. That is really what inspired me to write the grant for the award. When somebody at an oil company says, 'This is our primary corrosion threat, ... this is the thing that keeps us up at night, I thought, 'Well, that is what we should be working on.'"

Corrosion takes years. By developing a tool that can accelerate that process, Cullin and Johnson hope to give industry another way to know when they need to intervene, rehab and replace pipeline compromised by corrosion. The tool can also be used as a safe way to test potential mitigation solutions to corrosion.

"In general, oil and gas operators are not going to let you just play around and try different solutions on their pipe," Cullin said. "The consequences are just too high. So it really limits you when you are trying to develop new products or techniques to try to address corrosion. The risk of an unproven technique is just too great to practice on a pipe with oil flowing through it."

That's when a tool that can mimic true pipeline conditions becomes really handy.

What does the tool look like?

The tool, or "test apparatus" as Cullin and Johnson call it, exists now at UAA, near the Engineering and Industry Building. We would have taken pictures, but both of them laughed when we asked - it's not terribly photogenic. "It's a pipe, with a few wires," Johnson said. Part of it, the control system, is inside a six-foot Conex trailer, and part of it, the actual pipeline with its heating elements and spray apparatus, sits on a frame outside the Conex.

Yes, the tool has a pipeline. No, it does not have oil flowing through it.

"In fact, we considered using oil as the heat transfer fluid to maintain the temperature of the pipes. The problem with that is we plan to expose these pipes to really aggressive corrosion conditions. It would be ironic and sad if we ended up spilling oil in an effort to prevent spilling oil ... so we went with resistance heating elements. They look like the hot coils in your toaster. We are just toasting the inside of the pipe."

The final tool will have four pipeline segments. Most of the past two years, they've worked with just one segment - developing a mechanism to warm the pipe, a spray system that could dampen the exterior (remember, corrosion takes wet pipe), and an automated data recording and controlling system.

"The one pipe we have in there, we have been testing for about a year," Cullin said. "Keir has been running the tests on it. And we found some fun little errors that we have worked out. Now we feel pretty confident that we are ready for the additional units. We just bought them and they are on their way up."

Why four pipe segments? Cullin explains: "It scales up quickly so you can screen things. If I want to try one mitigation strategy at three different temperatures, instead of running a six-month test at one temperature, and then changing it out to test it at another temperature ... I can run three different pipes at three different temperatures over the same six months."

The toughest part

Johnson, who graduates in the fall with a mechanical engineering degree, said the biggest challenge for him was less the mechanical elements he needed to build for the test apparatus, but more the control and alert system he designed and built.

"The most challenging thing for me was the programming," he said. "I don't have much experience programming computers. I am a mechanical engineer and that's more of a computer science job. It took a lot of learning on my part about different protocols for how computers talk to each other, and automating the system to work with each other."

On the other hand, it was his favorite part. "It was the most challenging AND the most rewarding," he said. "Because, at the end of the day, we have a system that has all the safety features. It will shut off automatically if the temperature goes over a certain point. It will send us an email if anything goes wrong."

Cullin confirmed the efficiency of the automated warning system. "From a safety perspective, it's nice to know when something is going wrong. I can't tell you how many times I just did something in a lab, and you come back the next day it's like 'noooooo, oh nooo...' I wish I'd gotten an alarm on that one. Then it's just time to clean everything up and start again."

How to use the tool

Cullin described three ways the tool can be useful to North Slope oil field operators. Now that the endowment seed money has created the tool, he can imagine oil companies paying UAA smaller fees - $20,000 to $40,000 - to test corrosion problem solvers.

"Say the operator sees what he or she thinks might be a corrosion problem," Cullin said. "They can tell us, 'Here are the conditions, can you do some testing for us?' Or, 'We have this idea. We are thinking of trying this. We have a bunch of people who think this is a good idea. Give it a try, let us know if you see any red flags.'"

Remember, you never want to test anything for the first time on a live pipe with oil flowing through it. So the testing apparatus can closely simulate the conditions (temperature, environmental conditions) that the pipeline is experiencing. Although plans are for this first apparatus to stay at the UAA campus, Cullin said it is portable enough to be moved to the North Slope and set up right beside the actual pipeline.

He also sees a scenario where a company may want to duplicate the UAA tool so it can deploy it for its own problem-solving. So a firm might hire UAA to build them one. With all the research and development now complete, Cullin estimates they could provide a proprietary testing apparatus for about $45,000.

The testing apparatus can also accelerate corrosion. Say a company wants to test a CUI mitigation strategy. "We make the environment 10 times more aggressive than the field and if you see a vast improvement you can sort of extend that. 'OK, we did see a good improvement in this really aggressive environment, so it stands to reason we will see some improvement in our less aggressive environment.'"

The flip side of that, he explained, is that if the aggressive testing did not cause a ton of problems, "it is less likely to cause us problems in a less aggressive environment."

A lot of times the tool can be used as an independent third party, said Cullin. "The operator will say, 'We have a vendor who says they've got this new product and it's going to solve our problem. Do a side-by-side test and let us know if there is actual empirical evidence, unbiased empirical evidence, that supports the vendor's claim.'"

Written by Kathleen McCoy for UAA Office of University Advancement

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