Fiberglass pultruded structural products are components used to create structural aspects of a cooling tower, like railing, supports, etc. These products are becoming an increasingly popular choice for cooling tower installations due to their strength, durability, and resistance to corrosion. In this blog, we’ll discuss recommendations for the design and installation of fiberglass pultruded structural products, including:
Glass fiber-reinforcements may be either continuous rovings, continuous strand mats, woven or non-woven fabrics, unidirectional fabrics, or combinations of these. Glass fibers shall be made for A, C, E, E-CR or S-type glass. Other reinforcements may be specified for custom applications. The most common types of glass and glass forms used in pultruded shapes for cooling towers are:
The resin used throughout the part shall be either an isophthalic polyester, vinyl ester or other resin agreed upon between the cooling tower owner/operator and cooling tower manufacturer. The resin may contain additives for various purposes such as:
These additives should be selected to improve the overall performance of the product, without affecting the structural properties, chemical resistance, and/or longevity of the part.
The design criteria for pultruded, flat sheet, and structural shapes used under flexural and/or compressive loads must be obtained from an appropriate engineering design guide (i.e. The CTI FRP Design Guideline ESG-152) or the pultrusion supplier.
For structural products that are subjected to temperatures greater than 77°F for extended periods of time, the pultrusion supplier’s design criteria for flexural and compressive loads must be reduced to account for higher temperatures. These correction factors are published in CTI Standard 137.
All structural components for the tower should also be designed to account for maximum expected hot water temperature. This will help account for the possible effects of fan-off operation, the tower being idle in hot weather, and load excursions. A statement indicating the design temperature should also be included as part of the cooling tower manufacturer's proposal.
Quality Assurance Inspection
To ensure the consistency of the fiberglass reinforced pultruded structural products, a quality assurance inspection should be performed. The final acceptance criteria for these products should be agreed upon by both the pultrusion supplier and the cooling tower purchaser. The requirements for passing a routine quality assurance inspection are as follows:
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