Corrosion is one of the biggest problems contributing to leaks and ruptures of industrial pipelines. It is the natural process where materials made from metal electrochemically react with the environment and deteriorate. What is Internal Pipe Corrosion? Internal pipeline corrosion is a gradual process that causes the surface of a pipeline to break down or degenerate. This eventually leads to a material loss in the form of pinhole leakage, cracks, and splitting. Time can exacerbate the effects of internal pipe corrosion as it is much harder to detect and can continue unseen until it causes a pipeline failure. Corrosion is a time-dependent threat; therefore older pipes are at an increased threat of internal corrosion as are pipes with aging protective coatings. Why is internal pipe corrosion detrimental to oil and gas pipelines? Internal pipeline corrosion causes approximately 60% of corrosion-related failures. A failure of a pipeline is detrimental to the longevity of those assets and can greatly compromise operations at a water and wastewater or oil and gas facility. The breakage in a natural gas facility can impact natural gas production and transportation speed or bring operations to a complete standstill because of connectivity issues. What are the Main Causes of Internal Corrosion? Internal pipeline corrosion problems of oil and gas pipelines are caused by chemical reactions on the internal surfaces of the pipelines due to the presence of water, oxygen, electrolytes, and certain molecules, including carbon dioxide (CO2), hydrogen sulfide (H2S), organic acids, caustics, and certain organic chemicals. Corrosion rates are highly dependent on a number of factors such as operating temperature, flow rate, turbulence, pipeline geometry, holdup points, the combination of contaminants within the pipeline, and other factors. Whether pipes are transporting potable water, fire water, wastewater, or natural gas, the steel will corrode over time. If left unchecked, pipeline incidents can range from pitting corrosion, to complete through-wall failure. Corrosion Accelerating Factors Here are several examples of these factors that lead to and increase the damage of internal pipeline corrosion: The pH of the water The acidity of a water sample is measured on a pH scale. The pH scale ranges from zero (maximum acidity) to 14 (maximum alkalinity); the middle of the scale, 7, represents the neutral point. Both high and low pH will increase the rate of corrosion. Other contaminants can also affect the pH of the water. The amount of oxygen in the water Dissolved air in water consists of about 20% oxygen. The presence of oxygen, water, and an electrolyte allows an electrochemical process known as internal oxidation to occur. Higher levels of oxygen will increase the corrosion rate while removing oxygen will completely eliminate it. The chemical makeup of water Dissolved minerals may have differing effects on pipe corrosion. Elevated hydrogen sulfide levels will drastically speed up the internal corrosion in the oil and gas and sewage and wastewater industry. Elevated levels of calcium can cause a calcium build-up in your pipes. The temperature of the water Experience shows that corrosion is more pronounced in hot water lines. The higher the water temperature, the faster it will occur. The velocity of the water Corrosion occurs at locations where water turbulence develops. Turbulence can be caused by excessive velocity, sudden changes in direction (sharp turns, elbows), and through “flow” obstacles such as burrs and solder excess. Pipe elbows are more likely to corrode over time. Microbiologically influenced corrosion (MIC) Microorganisms such as algae, bacteria, and fungi do not directly consume metal in most cases, but instead can create aggressive environments where localized corrosion can occur, leading to severe degradation, like wormholes and pitting. Many industries are affected by microbial corrosion, including Oil & Gas, Power Generation, and Water and Wastewater. MIC is common in crude oil pipelines where oil is extracted directly from the earth. Power generation facilities that use a local source of water for cooling are especially prone to internal corrosion. Unless the water is treated with corrosion inhibitors and biocides, microbiological growth in that water can cause pitting and crevice corrosion. Even stainless steel can suffer from pitting and stress corrosion cracking from MIC. Modification to the pipe exterior External welding will damage or destroy the internal coating and may lead to significant, localized corrosion damage and eventually a through-wall failure. Detecting and Preventing Corrosion on Pipes Preventing internal corrosion begins with having a detection method in place. Corrosion monitoring is challenging and different methods should be applied depending on the system. Here are a couple of examples of corrosion monitoring: Ultrasonic Thickness Monitoring Some forms of corrosion are fairly static meaning large areas will have a similar corrosion pattern. In this case, an ultrasonic thickness measurement (UTM) monitor can be placed on the outside of the pipe to map the level of corrosion over time and help with corrosion prevention. Regular Pipe Inspection Some other forms of corrosion are very isolated, such as coating failures from MIC that are not seen throughout your entire system. For those types of issues, regular inspection is critical. Regular inspection not only helps maintain the physical integrity of pipelines but also extends their lifespan, reduces environmental hazards, and saves on replacement costs. We always recommend talking to an expert to determine the best corrosion monitoring technique or techniques for your system and ensure that it is implemented. Assessing the Wall Loss and Taking Preventative Steps after the Corrosion Detection Once the corrosion has been identified, it is important to look at the original wall thickness. Any loss of 2% or 5% of your wall is well within your corrosion tolerance. Internal corrosion may be kept under control by establishing appropriate pipeline operating conditions and by using mitigation techniques and applying regular maintenance. Once past 20% of the original wall thickness, a pipeline operator needs an intervention to stop the corrosion before leaks occur, whether it is an installation of the internal coating system or the application of a pipeline cathodic protection system. Internal Pipeline Corrosion Prevention Strategies Internal Pipeline Coatings The first defense against internal corrosion of a pipeline is a high-quality, immersion-grade coating. Advanced FRP offers a variety of coatings systems designed for use in water-immersion services, including in aggressive services like industrial wastewater, hydrocarbon-contaminated water, and even services that are at risk of MIC. Our water-immersion coatings are engineered with lamellar fillers to decrease the rate of water permeation and are designed to eliminate the most common causes of coating failures even in difficult application conditions. Internal Pipe Repair with Carbon Fiber Composite Corrosion from severe MIC or aggressive materials, as well as isolated pipe corrosion, can be fixed with an internal carbon fiber system, Internal pipe repair with carbon fiber composite provides a long-term life extension of your assets. With more than 10 times the strength to weight ratio of steel, internal composite carbon fiber repair can repair and structurally rehabilitate even the most badly corroded pipes. Internal pipe repair can be done on pipes above 32 inches in diameter because it does take a technician in the pipe to install. The biggest benefit of internal pipe repair is that it is a permanent solution, no matter what state of degradation your pipe has. Engineered solutions are available that provide more than 50 years of additional service life. Need Corrosion Prevention or Internal Pipe Repair? Contact us. Do you need help in identifying the corrosion rate? Are you interested in learning more about methods to prevent internal corrosion? Advanced FRP Systems’ engineers can help you with assessments of your existing pipelines, run a failure analysis of problem areas, and provide customized corrosion control mapping. If you are in need of pipeline repair, we can provide long-lasting, maintenance-free carbon fiber repairs for industrial pipes. Our internal repair system for damaged pipes can be used for spot repairs on leaking pipes or to completely rebuild your piping system with a high-strength, corrosion-resistant carbon fiber composite pipe. Whatever structural pipe damage you may have, don’t hesitate to contact us and we’ll find the right composite solution for you.