Structural Design Guide of FRP Components

CTI has recently developed a structural design guide about the newest building materials for constructing cooling towers, Fiber-Reinforced Polymers (FRP). This paper is available on CTI’s website and includes the minimum design standards and cautionary recommendations to designers for FRP structural cooling towers.

What are FRP Components?

When investing in a cooling tower, it is important to consider what type of materials will be used to build it to make the structure long-lasting. With this being said, what are FRP components? Fiber-Reinforced Polymers are composed of large molecules and a protective reinforcement layer of high-strength fiberglass. FRP components are trending in popularity due to their superior durability, corrosion resistance, and affordability. Additionally, these types of polymers offer an optimal strength-to-weight ratio.

Some of the other materials that are used to build cooling towers are as follows: wood, concrete, and steel/aluminum. When using wood in a cooling tower, this type of material is known for rotting or decaying due to being exposed to water all of the time. Also, wood is susceptible to insects or termites. Additionally, wood materials in cooling towers require a lot of work to maintain the condition. With concrete, while it is a strong element, dirt and other bioforms tend to accumulate and this requires a lot of maintenance. Lastly, when using steel or aluminum in cooling towers, these materials tend to rust faster than other materials due to being exposed to water.

However, when it comes to FRP components, they are resistant to both water and moisture. Fiber-Reinforced Polymers also can withstand chemicals and are much stronger when compared to the other materials. This makes FRP components the perfect choice for building cooling towers.

Summary of CTI’s FRP Component Guide

When using FRP components for a cooling tower, it is important to keep in mind the amount of allowable loads that will be used as this will affect how the cooling tower is set up. Also, it is essential to understand that the composite materials lose strength at elevated temperatures. With this being said, when building the cooling tower, make sure that the reduction factors, including compression strength, elasticity, and water immersion, are taken into account. Additionally, if all of the proper precautions are taken, a FRP-structured tower should last between 30-35 years.

Another standard to take into consideration when building a cooling tower is fabrication standards. These types of standards are important because they give the designers all of the necessary information to build the tower precisely and efficiently. For best results in terms of equipment, carbide-tipped or plated diamond grit saw blades, bits, files, and planers are recommended. Also, when determining the best joint for application, an emphasis should be placed on the method of determining the strength of a specific joint. In addition, a series of connection tests should be performed to make sure that the joint is being utilized correctly.

The bearing capacity is another important factor to keep in mind. This type of capacity is made up of the pultruded FRP material around the fastener. The bearing capacity is affected by the edge and end distances between the fasteners in a line (pitch). With this being said, there are recommended ratios to follow. This information can be found in CTI’s paper.

Once the cooling tower is ready to be built, a fabricator should provide quality control procedures to make sure that all of the work is performed in accordance with the shop drawings. Also, if applicable, there may be an inspection of the procedures, contract documentations, and shop drawings by qualified inspectors on behalf of the purchaser. If an inspection is taking place, the inspecting agency should provide at least a 24-hours’ notice to the purchaser and the cooling tower manufacturers.

Additionally, CTI’s paper guide includes nine important tables for the designer to utilize when building a cooling tower. The tables cover the following topics:

  • Application Condition vs. “Average” Compression Strength Reduction

  • Application Condition vs. “Average” Modulus of Elasticity Reduction

  • An Example of a Fill Support Beams Design Temperature

  • Total Water Immersion Reduction Factors

  • Joining Method Considerations

  • Comparison of Joining Techniques

  • Types of Mechanical Fasteners

  • Recommended Minimum Fastener Edge Distances to Fastener Diameter Ratio

  • Fabrication Tolerances

Lastly, this CTI paper includes a 7-page Pultrusion Terms Glossary. The glossary includes important words and definitions for the designer to utilize to make sure the cooling tower is built with the utmost care.

Interested in learning more about FRP Components? If so, purchase CTI’s full standard paper here!

How Can CTI Assist With Your Cooling Tower Needs?

Cooling Technology Institute has published a plethora of papers about various cooling topics. CTI is also an advocate in promoting the use of environmentally responsible Evaporative Heat Transfer Systems (EHTS), cooling towers, and cooling technology for the benefit of the public. Additionally, CTI is an independent, third-party thermal performance testing to help participating manufacturers and owners/operators achieve the best performance from their cooling towers.

For more information, contact us today or purchase one of our informative papers!

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