How to Detect and Prevent Corrosion Under Insulation in the Oil and Gas Industry
Corrosion under insulation (CUI) is one of the problems crippling the gas and oil industry.
It can cost companies a lot of money every year in repair, inspections
, and replacement costs. It refers to a form of corrosion that occurs between the material used for insulating gas lines and the outer surface of a pipeline. corrosion under insulation is the cause of most leaks experienced in the oil and gas industry. It is also one of the problems that companies in the gas and oil industry are struggling to address. Water will always seep into the insulating materials and eventually damage the inner and outer surface of the pipeline.
What Conditions causes Corrosion Under Insulation to Develop?
The coating on the surface of the gas line can be inadequate to retard or prevent corrosion. An ineffective protective layer can cause acidic gases and water to penetrate the outer surface of the gas line. This will make the insulating material absorb acidic water. As a result, corrosion cells start to form between the insulation materials and the surface of the pipe. Also, extreme temperatures after rain storms will result in the influx of oxygen and water vapor. This can accelerate the growth of CUI. As a result, general attack corrosion, which can develop into localized corrosion if left unattended will occur. Localized corrosion may appear in the forms of filiform or crevice corrosion on the outer surface of the coating of the pipeline and cavities or pitting on the outer surface of the gas line.
Insulating materials such as fiberglass, foam rubber, Rockwood, and polyurethane absorb leachable chlorides, oxygen, and water at a higher rate. Any insulator that has a high porosity can absorb acidic chemicals and water quickly. As such, it is crucial to consider the water and acidic properties of an insulating material, its effectiveness, and cost before purchasing it.
What Damages can CUI Cause?
When CUI inspectors fail to detect it early enough, it can cause petroleum products and gas to leak. Gas and petroleum leaks are dangerous and costly for a technician to repair. They can also create health hazards for the surrounding community and pollute the environment. You need to replace gas lines and the insulating materials immediately after you detect corrosion under insulation. However, this repair process can be time-consuming and expensive due to workforce utilization and downtime. The insulation cover makes it impossible to detect CUI visually because it covers the outer surface of the gas line. You may need to employ the NDT inspection technique to remove the clad and insulation cover to inspect the pipelines visually.
Tips to Eliminate or Prevent Corrosion Under Utilization
Preventing the absorption of acidic water into the insulating material is the primary method of eliminating CUI. You can also prevent CUI through the use of a high-quality insulating material. For example, wrapping an aluminum foil on a pipe before placing the insulating material on it can inhibit corrosion. Aluminum foil acts as a barrier that prevents the insulator from absorbing acidic water. It also ensures it doesn’t reach the outer surface of the pipe. Alternatively, application of paints such as epoxy-phenolic and epoxy and protective coatings on the outer pipeline surface can prevent penetration of acidic water.
Use of water-repellent coatings and moisture barriers on an insulating material can also go a long way to avoid CUI. Finally, regular maintenance such as re-applying paints and insulating material can help prevent CUI and reduce downtimes. While none of corrosion inspection techniques are foolproof, engineers can use Frazier Reliability Solutions
to analyze the presence of corrosion without interfering with the insulators. Furthermore, most of these corrosion inspection methods
don’t show the extent CUI has damaged a pipe.
Pipeline Inspection Techniques
You can use any of the well-known pipelines inspecting techniques
in the oil and gas industry to detect CUI. You may use either insulation removal, radiography, or cut plugs to allow ultrasonic testing. Drone-assisted gas line inspection technique is the most efficient and least expensive method of CUI detection. Pulsed eddy current testing, neutron scattering, ultrasonic thickness measurement, and radiography or X-rays are some of the areas where one can apply NDT inspection.
Conversely, drone-assisted corrosion testing technique uses imaging and thermal infrared sensors to analyze the presence of rust on the outer surface of a pipe. Drone-based CUI inspection might soon aid the gas and oil industry in CUI prevention once it reaches its maturity and experts assess its cost-effectiveness and reliability. Companies have to monitor the condition of all their equipment and prevent unnecessary breakdowns so that they can know the time to replace them. The cost of avoiding CUI is relatively lower than to replace or repair the entire piping system. However, it’s often difficult to access equipment at the plant due to the insulating materials, and this makes it difficult to identify a potential leak.