Circulating water lines are pipes used in power generation facilities, chemical plants, oil refineries, and other heavy industrial applications. They differ in terms of design requirements but have common features and common reasons for failure. Today, repairs for circulating water lines can use several different methods. Each method has its place, which is why it’s important to find a partner who can recommend the right one for your application. Common Causes of Failure Most circulating water lines fail because of corrosion. Water corrodes steel, so it is only a matter of time before leaks occur. To prevent corrosion, the pipes in circulating water systems should have immersion-grade coatings; however, maintenance crews may not realize that these coatings are actually semi-permeable membranes that allow water to slowly permeate through the film. There are other coating-related considerations as well. The age, quality, and thickness of coatings varies, and their integrity can be affected by the purity and temperature of the water, or by pipe modifications and repairs. Poorly Designed Riser Pipe in Immersion Conditions Maintenance personnel should also consider the age of a facility, including when pipes were coated and how a failure to remove chloride and other ions enhances water permeation. Many power generation facilities, chemical plants and oil refineries are old and have maintenance plans for circulating water lines that are out-of-date. Protective coatings have a service life, but some facilities managers may not know when pipes were coated. Corrosion is rarely noticeable right away, but will gradually work through your pipe walls causing through-wall failures with costly consequences. A proactive inspection program is the only way to ensure active corrosion is not taking its toll on your pipes. Corrosion isn’t just a problem at plants with aging assets and infrastructure. Facilities that are less than five years old can experience significant corrosion even if protective coatings were installed. Years ago, plants were built from the ground up. Today, newer facilities are modular to reduce costs. With commodity-type construction, thinner pipe coatings are used to reduce costs. These thinner coatings may only last until the warranty period is over. Plants may even see pipe failures sooner – and not just in new construction. Replacement piping can have an inferior coating or no coating at all, increasing the risk of leaks. Pipe modifications and corroded pipe repairs can also ruin coatings. Welding a new injection port or inlet onto a pipe burns off the interior coating. Welding a metal plate onto a pipe to stop a leak also damages the coating, which is why corrosion commonly occurs next to the weld. The application of internal coatings is often not possible for emergency weld repairs. When internal coatings are applied they are often applied without proper surface preparation, applied too thin, or in a single layer prone to pinholes. Corrosion Behind Poorly Adhered Fiberglass Coating Through wall failure at an external welded repair Inadequate installation and irregular maintenance practices can also contribute to failure. A common refrain in the industry is that 90% of coatings fail because of poor surface preparation. Many facility managers also practice a “run-to-failure” strategy when the costs or accessibility of preventative measures are too prohibitive, and perform a repair only when an asset fails. Contrary to the belief that this strategy lowers overall maintenance costs, repairs can be very costly and require a temporary shutdown of operations, causing a significant financial loss to the facility. Poor Surface Preparation Leads to Coating Failure Water purity and temperature may also contribute to corrosion-related failure. Many facilities use water from a convenient source such as a river or lake. Filtration systems remove large sediment but not small particles. In pipe elbows, this finer sediment causes erosion. Microbially-influenced corrosion occurs, too. Hot water in cold pipes is more aggressive on coatings and creates a condition known as the cold wall effect. That’s why in power plants, condensers are common sites for osmotic blistering. Osmotic Blisters after only 2 Years in Service Severe MIC Pitting After Blast, more than 80% wall loss Experiencing Failure of Circulating Water Lines? Contact us. There are numerous causes of failure in circulating water lines, from corrosion to poor installation and irregular maintenance to water purity and temperature. If you are experiencing problems with circulating water lines, whether in a power generation facility, chemical plant, oil refinery, or other heavy industrial facilities, contact us for a free consultation. The Advanced FRP experts can inspect the system, thoroughly diagnose your corrosion problems and prescribe streamlined, custom solutions.