6 Reasons to Use Fiberglass Reinforced Plastics (FRP)

The use of Fiberglass Reinforced Plastics (FRP) in wastewater applications has grown since their introduction in the 1960’s. Their increasing use can be attributed to six key factors:

Superior Corrosion Resistance

Wastewater is a corrosive environment.

Hydrogen sulfide is the leading cause of corrosion, but chlorine and other chemicals can corrode equipment both above and below the waterline. The orthphathalic polyester resins used to make flumes, weirs, flow metering manholes, and equipment enclosures resists the oxidizing effects of these chemicals, and protected by Iso/NPG gel coats, equipment made from these resins should give long useful lives.

If an application is particular aggressive, or the flows will experience sustained high temperatures, other resin chemistries (isophthalic and vinyl ester) can be used. Likewise, surfacing veils can be applied to the surface to provide an additional layer of protection.

Lightweight

Equipment fabricated from fiberglass can be very lightweight for its size. For a flume, a ¼-inch wall thickness is common. In fiberglass the weight (with reinforcement) is 2-2.5 lbs/sq. ft. A comparable flume in 12-gauge stainless steel weighs 4.4-5 lbs/sq. ft., while in aluminum the weight would be between 2.5-3.6 lbs/sq. ft.

Lighter weight means:

• Lower shipping costs
• Fewer personnel are needed to install the equipment
• Less expensive equipment is needed to move the equipment once it is on site

High Strength

Structural fiberglass exceeds the strength of many steels in the lengthwise direction at ¼ of the weight.

Minimal Maintenance

The high strength and superior corrosion resistance means that fiberglass equipment requires little in the way of regular maintenance. Other than a periodic wash down with a mild detergent (and potentially an application of wax if the surface needs to retain a gloss finish), there is no need to periodically coat, paint, or descale fiberglass.

Also, U.V. degradation (oxidation of the resin) can be slowed by the use of high quality Iso/NPG gel coats with U.V. inhibitors.

Shape Versatility

Working from master molds, fiberglass can be molded into complex shapes and geometries that are difficult or expensive to fabricate in other materials.

For truly complex geometries, fiberglass equipment can be fabricated in multiple sections and then chemically bonded together – resulting in a seamless, single-piece structure.

Dimensionally Exact

Precise master molds allow fiberglass equipment to achieve tight dimensional tolerances. In flow measurement, this is particularly important and any deviations from the nominal dimensions of a flume or weir will result in decreased discharge accuracies.

Low Cost

The resins, gel coats, and reinforcements used to make standard polyester fiberglass are relatively low in cost and typically only hand tools are needed to fabricate parts (no welding rigs or cutting torches), fabrication costs are usually lower than other materials.

Even when master molds are not available and the construction is one-off, fiberglass is still cost competitive.