Creating a Better Oil Pipeline - IEEE Spectrum

Pipeline inspection technology was a ho-hum subject until August, when an oil spill from a leaking pipe forced BP Plc to shut down operations at Prudhoe Bay, Alaska, cutting U.S. domestic production capacity by nearly 8 percent. Traders bid up the price of oil futures, environmentalists added sloppy maintenance to their list of reasons not to develop reserves in sensitive areas elsewhere, and pundits began bandying arcane terms of trade, notably pigs --machines that move inside pipes with flowing oil and inspect or clean as they go.

Check now

Separating the hype from the facts, it's plain that the Alaska incident points to serious lapses on BP's part. It also gives us a chance to analyze how up-and-coming technologies might help detect corrosion and other problems at other aging oil fields around the world.

Inspection cannot by itself keep pipes from corroding, but it can at least catch the problem before it gets bad enough to cause a rupture, which can result in fires, explosions, and widespread pollution. That way, oil companies can plan to close down and repair lines.

Inspection should have been even better at Prudhoe Bay than in many other oil fields, because its pipelines were visible, having been built, of necessity, above permanently frozen ground. But "humans aren't as rigorous as machines," as one NDE expert noted. Further, humans can’t see what’s going on inside a pipe.

BP says it used ultrasonic, radiographic, magnetic flux, guided wave, and electromagnetic NDE methods to see inside the pipes in Alaska. All were deployed by sensor-laden ”smart” pigs that inspect pipes instead of scouring them. Pigging has been practiced in one form or another for decades, but BP did not make regular use of it on the particular transit line that ruptured in August .

Rust Never Sleeps

Since corrosion is inevitable, oil-pipeline companies must take steps to minimize it. They have steadily improved the steel alloys in the pipes used to transport crude and gas, improving safety, according to a recent report by the Pipeline Research Council International Inc. Most pipelines now use fusion bond epoxy coatings, like those used on ship's hulls, to reduce corrosion.

Another approach, called cathodic protection, targets the electrochemical root of corrosion�a battery-like process in which differing electric potentials create a current that oxidizes iron. The result is the weak compound iron oxide, otherwise known as rust. One way to protect the pipe is by applying sacrificial anodes�metals that corrode more readily than iron and thus sop up the current. Another, more active way is to apply a small countercurrent to the pipe.

Maintenance workers can also add chemicals to control the microorganisms that feed on organic materials and secrete chemicals that speed corrosion. Such microbial action is currently thought to have caused the recent problem in Alaska.

Finally, there is mechanical cleaning by pigs. But to do it right, workers must first assess the pipeline’s condition. One way is by inserting small bars of pipeline material, called corrosion coupons, into the oil stream and then take them out for analysis after a set period. This method gives the overall rate of corrosion but cannot pinpoint its effects.

To do that job requires smart pigs with more advanced inspection techniques, such as magnetic flux leakage (MFL) and ultrasonic transduction (UT). An MFL pig uses magnets to induce a strong magnetic flux in the wall of the pipeline, senses any leakage of flux, and uses the data to deduce how much metal has been lost, and from which places. A UT pig sends sound waves through the pipe and compares the speed of their propagation with what would be expected in a pipe of the proper thickness. A UT pig generally has some 500 transducers and takes 625 readings per second, according to Alyeska Pipeline, the operator of the Trans Alaska Pipeline System.

High-Tech Pipes

Smart pigs do have their limitations. They can be as long as a car, and cannot navigate many pipes. To remedy these faults, the industry envisages smaller, svelter robots that move under their own power and go wherever the operator desires, no matter the direction of the flow of oil (or natural gas, in gas pipelines). These robots will require much lighter sensors, and researchers are looking at a number of techniques.

J. Bruce Nestleroth and Richard J. Davis, of Battelle, based in Columbus, Ohio, describe one sensing method in an article published on August 30 in the journal Nondestructive Testing and Evaluation International. They use a device that moves through a pipeline while rotating pairs of permanent magnets around a central axis, stirring up powerful ”eddy currents” in the surrounding metal. Variations in these currents can paint a detailed picture of the pipeline’s walls.

Another method, remote field eddy current (RFEC) testing, uses a coil of wire carrying low-frequency alternating current to induce the eddy currents. Such coils can be made quite narrow, and can thus be used to inspect ”unpiggable” pipes from inside. The Department of Transportation is funding projects to test this idea in natural gas pipelines.

The best corrosion-detection technologies can be effective only if they are implemented.

The best corrosion-detecting technologies can be effective only if they are implemented , and they aren’t cheap. Before the Prudhoe Bay disaster, BP expected to spend US $72 million on corrosion control. Now, it forecasts it will spend $195 million in on major Prudhoe Bay maintenance.

If you are looking for more details, kindly visit Dragon.

Add to that cost the ill will generated by the bad press and the embarrassment of having a former BP corrosion manager plead the Fifth Amendment during a U.S. House of Representatives Energy and Commerce subcommittee hearing. As any risk-management expert will tell you, risk mitigation is less expensive than crisis management. That message is certainly resonating loudly through the executive offices of many an energy company these days.

Chemical treatments are a critical tool in pipeline operations, designed to mitigate damage mechanisms and optimize performance. From preventing corrosion to managing deposits like wax or scale, the application of the right chemical solutions ensures your pipeline operates efficiently while maintaining its integrity. Let’s dive into the key aspects of chemical treatments in pipeline operations:

What Are Pipeline Chemical Treatments?

Chemical treatments involve introducing specialized additives into a pipeline system to address specific challenges. These treatments are tailored to the pipeline’s operating conditions, product type, and damage mechanisms present.

Some common chemical treatments include:

• Corrosion Inhibitors: Form a protective barrier on the pipeline's internal surface to minimize corrosion caused by water or other corrosive agents.
• Scale Inhibitors: Prevent the formation of mineral deposits that can clog pipelines or reduce flow efficiency.
• Wax Dispersants: Break down wax deposits in pipelines transporting crude oil, ensuring a steady flow.
• Biocides: Target and eliminate microbial activity that could lead to microbiologically influenced corrosion (MIC).
• Hydrate Inhibitors: Prevent the formation of gas hydrates that could block flow in gas pipelines.

The Purpose of Chemical Treatments & Their Outcomes

The key to an effective chemical treatment program lies in the optimization of dosage and validation of performance. Chemical treatments deliver several critical outcomes:

• Corrosion Control: Extends the lifespan of your pipeline by reducing internal corrosion, a leading cause of pipeline failures.
• Flow Assurance: Prevents blockages and ensures that product flow remains steady and consistent.
• Operational Efficiency: Reduces the need for reactive maintenance by addressing potential issues proactively.
• Cost Savings: Helps avoid expensive repairs and unplanned downtime caused by corrosion or blockages.

The Challenge of Optimization

While chemical treatments are highly effective, they require precise management to ensure success. Optimization isn’t about cutting costs or reducing chemical usage—it’s about finding the right balance to achieve the desired outcomes.

• Too Little: Insufficient treatment can lead to continued damage or failure to prevent issues like scaling or corrosion.
• Too Much: Over-treatment leads to unnecessary costs without additional benefits, and in some cases, it can even introduce new challenges, such as product contamination.

Monitoring & Validation: The Key to Success

One of the biggest challenges operators face is monitoring the effectiveness of chemical treatments in real-time. Changes in flow or process conditions can significantly impact treatment results, requiring constant validation to ensure:

• Proper Dosage Levels
• Performance Under Variable Conditions
• Adaptability to Operational Changes

By using historical trends, process data, and monitoring systems, operators can fine-tune their treatment programs to achieve the best possible results.

Integrating Chemical Treatments into an Integrity Management Program

Chemical treatments don’t work in isolation—they are a vital component of a broader integrity management program. Combined with other strategies, such as maintenance pigging and monitoring, chemical treatments play a key role in ensuring pipeline safety and performance:

• Corrosion Inhibition: Works in tandem with pigging to remove water and deposits while preventing new corrosion from forming.
• Data-Driven Decisions: Monitoring and analyzing the performance of chemical treatments provides valuable insights that inform operational strategies.
• Proactive Maintenance: Chemical treatments allow operators to address potential risks before they escalate, reducing the need for reactive solutions.

Challenges & Success Stories

Implementing an effective chemical treatment program is not without its challenges. Operators must deal with changing process conditions, variations in product composition, and limited visibility into treatment effectiveness. However, the results of a successful program are undeniable:

✅ Reduced Internal Corrosion Rates: Protecting assets and extending their useful life. ✅ Minimized Downtime: Ensuring uninterrupted flow and operational efficiency. ✅ Improved Safety: Reducing the risk of leaks or failures due to corrosion or blockages. ✅ Cost Optimization: Balancing treatment costs with measurable performance improvements.

For more information, please visit Chemical Pipeline(de,ru,fr).