Fiber-Reinforced Plastic (FRP) tanks, scrubbers and pipes are highly valued for their corrosion resistance, durability, and lightweight yet strong construction. These units serve a wide range of applications, particularly in chemical, paper and power plants. They are also ideal for use as storage tanks in the chemical industry.
While FRP equipment is known for its longevity, regular inspections are essential to ensure ongoing durability and safety. Abtrex’s FRP quality control specialists conduct several thorough inspection procedures, including the pull test, which evaluates the equipment’s substrate saturation and its resistance to the chemicals it contains.
What is an FRP Equipment Pull Test?
When inspecting FRP tanks, scrubbers and pipes, a variety of quality control procedures are used to thoroughly assess the equipment’s condition. One of the most effective and reliable methods is the FRP pull test. In this procedure, a small FRP patch is applied to previously prepared surface of the unit, then pulled off under controlled conditions.
The test’s primary purpose is to assess the extent of chemical saturation within the equipment’s fiberglass substrate. This ensures the structure remains safe, functional, and corrosion resistant, extending its service life in demanding environments.
Why is the Pull Test Important for FRP Equipment?
A pull test is one of the most essential procedures for assessing the condition of an FRP equipment. While the unit’s structure may appear intact, its corrosion barrier could be compromised by saturation with the chemical solution it holds. Thorough inspections, and relining when necessary, can extend the lifespan by up to 10 years.
Regular monitoring of the condition of FRP tanks and other equipment is key to safe and reliable operation. Inspections help ensure that the fiberglass layer endures corrosive environments without delaminating. Pull tests are especially vital for equipment storing highly corrosive materials or subjected to high pressures, as these factors can accelerate wear on the inner lining.
The FRP Equipment Pull Test Procedure
The procedure involves preparing a small interior section of the fiberglass substrate by grinding down the outer surface. Next, an FRP test patch, made from the same material as the substrate, is applied to the bottom area, leaving a small exposed gap on one side of the patch. The patch itself is composed of the following layers:
- Two layers of Chopped Strand Mat (CSM): CSM serves as part of the corrosion barrier. Thanks to its random fiber orientation, CSM can be easily molded into various shapes, making it useful for building up thickness and performing repair work. It is typically mixed with resin in a 40% to 60% mat-to-resin ratio.
- Two layers of Veil: Veil also functions as a corrosion barrier, protecting the underlying layers by resisting chemical attacks. It creates a smooth, consistent surface finish on the fiberglass substrate. The veil is mixed with resin in a 90% to 10% veil-to-resin ratio. The final layer is carefully rolled to eliminate any air bubbles.
After application, the patch must cure for approximately 8 hours. Once cured, the patch is lifted using a pry tool to complete the pull test.
The Interpretation of a Pull Test Results
When interpreting pull test results, Quality Control inspectors focus on the bond between the patch and the substrate, as well as the process of patch separation. The force required to remove the patch is a key factor in evaluating the unit’s condition. If the patch detaches easily, it may indicate a weak bond between the patch and the FRP equipment substrate.
Similarly, a clean separation of the patch suggests a poor bond. In contrast, if the patch tears during separation or if part of the old FRP layer on the substrate is pulled away, this indicates a strong bond.
In cases where a weak bond is detected, the test may need to be repeated to accurately assess the depth of chemical saturation. If the pull test confirms a weak bond and deep chemical saturation, relining the entire tank may be recommended.
To ensure accurate results, the test must be conducted and documented according to industry standards and by experienced FRP Quality Control inspectors. Adhering to safety guidelines throughout the procedure is also essential to protect both the equipment and personnel.
The Role of Pull Tests in FRP Equipment Maintenance
The pull test is a vital procedure for maintaining the integrity and safety of FRP tanks and other FRP equipment. Regular inspections, including pull tests, play a crucial role in extending the life of the unit and preventing potential hazards associated with chemical saturation and weakened bonds. By thoroughly evaluating the condition of the fiberglass substrate, these tests help ensure that equipment continues to perform effectively in demanding environments.
Abtrex’s team of FRP specialists is equipped to conduct comprehensive inspections of FRP equipment and provide necessary linings, ensuring optimal performance and reliability for all your storage and chemical handling needs.
For questions or to request a quote, call us at 800-959-0125 or fill out our online form and someone will contact you.
