Article courtesy of Mike Keegan with Plasti-Fab, Inc.
Referring to a Plasti-Fab gate or stop log as FIBERGLASS is like stating a Porsche Carrera GT is just a CAR. They both might fit the basic definition, but that is where the similarities end! Conventional fiberglass molding and fabrication techniques (spray-up or chopper gun processing) are extremely good for a wide variety of products. Boats, bathtubs and pick-up tops for trucks have been produced in (FRP) Fiberglass Reinforced Plastic for many years. The availability of these products and many others fabricated in Fiberglass Reinforced Plastic (FRP), compared to being built from other materials such as metal and wood, brought numerous benefits to the product. Strength, light weight, impact resistance, flex modulus, corrosion and chemical resistance, and being easily repaired were just a few of the major advantages achieved with FRP construction. However, there are limitations with conventional FRP methods of production.
When products with a much more severe and demanding application range (products like gates and stop logs for industrial flow control) were considered for production with FRP, standard processing methods were not going to be adequate.
Conventional FRP processing involves applying a polyester resin and fiberglass onto a mold. The fiberglass can be yard good materials, woven with specific design specifications or strands (roving) cut to specific lengths and randomly distributed within the resin. In most cases, a combination of both types of fiberglass reinforcements is used to fabricate the FRP laminate. With conventional FRP processing it is difficult to achieve and maintain desired volume fractions (fiberglass to resin ratios) and this can effect physical properties. It is equally difficult to remove all the air from the laminate matrix creating porosity or micro voids that result in avenues for water migration during the osmotic process.
Both of the above negatives are completely unacceptable for gates and stop logs used in flow control at municipal or industrial settings.
In a conventional FRP production process you are giving the operator an engineering degree. In both manual and dispenser applied applications the operators can adjust the flow rates of resin and the volume of fiberglass being applied to the mold.
With conventional FRP processing it is necessary to manually “roll-out” the resin and fiberglass to remove the air from the laminate. This step is critical and is difficult to QC and can be unintentionally circumvented on the production floor at numerous stages in the process.
The raw materials, corrosion resistant polyester or vinyl ester resins and fiberglass reinforcement, were ideal for flow control products but conventional design, engineering and manufacturing processes were inadequate.
Plasti-Fab developed and refined a closed mold, vacuum infusion process for manufacturing flow control gates and stop logs. Plasti-Fab flow control products were no longer FIBERGLASS – they were an ENGINEERED COMPOSITE.
With every Plasti-Fab gate and stop log our engineering department develops a precise laminate schedule. Specific fiberglass reinforcements and core materials (steel, composite and high density polyurethane) are positioned exactly in a mold. The mold is closed and sealed and a vacuum is pulled on the mold removing all air. A precision injection machine then infuses the mold with the prescribed amount of corrosion resistant resin.
The Plasti-Fab design and manufacturing process eliminates all variables that can have a negative impact on the finished product. The result is a one-piece, completely seamless ENGINEERED COMPOSITE flow control gate and stop log. The Plasti-Fab manufacturing process creates a “sandwich construction” with the resin and fiberglass reinforcement encapsulating the core materials.
The seamless construction of the Plasti-Fab gates and stop logs differs greatly from other fiberglass offerings. Competitive products fabricate conventional FRP panels which are then attached to a metal skeleton. This requires typically six (6) panels that are affixed to the frame with adhesive or mechanical fasteners. The seams and points of contact of each individual panel are stress points and areas for moisture infiltration.
The Plasti-Fab gates and stop logs are one piece! There are no points of contact, seams, or panels that must be affixed to a frame.
In conventional FRP laminates, the micro porosity (air voids) create a conduit for the water to move within the laminate matrix. This has a negative impact on the short term and long term performance and lifecycle of the device. Plasti-Fab, by using a vacuum infusion manufacturing process, removes all air from the mold before injecting the resin. There is no potential of porosity or air entrapment in the part – the air has been removed.
Moisture related oxidation and corrosion on metal gates is an issue that needs constant attention from the first day of installation. Metal gate manufacturer’s recommendations to “exercise” the gates on a regular basis is testament to the fact that if you do not open and close the gates on a very regular basis corrosion and oxidation will quickly occur and prevent you from performing the gates primary function, to open and close.
An ENGINEERED COMPOSITE using “sandwich” construction will have the absolute best strength to weight ratio. Regardless of the size of the gate or stop log Plasti-Fab products will have superior physical properties and be substantially lower in overall weight.
Weight can be a major consideration in flow control gates for both manual and electric actuator installations. Depending on the size of the gate or stop log and the amount of head pressure the gate or log is subject to there are numerous operational and economic variables to be considered. If the gate is manually operated an extremely heavy gate or stop log can turn a routine function into an all day operation. When electric actuators are employed the size of the operator must be significantly bigger and more expensive and excess weight will put extreme stress, wear and tear on the expensive electric actuator.
Depending on the size, an ENGINEERED COMPOSITE gate or stop log from Plasti-Fab can be 20% to 40% less in overall weight compared to competitive offerings which typically eliminates the need for wall thimbles. When sluice gates of average or larger dimensions are needed most metal gates will require the use of a wall thimble adding dramatically to the overall cost of the gate and substantially increase contractor installation costs in time and materials.
All Plasti-Fab gates and stop logs are fabricated using polyester and vinyl ester corrosion resistant thermoplastics. The corrosion resistant characteristics of these materials, along with our advanced and proven design, engineering and manufacturing techniques allows Plasti-Fab to offer a 25 year warranty against corrosion and oxidation. No other manufacturer of flow control products can offer this type of performance assurance on their gates and stop logs.
Plasti-Fab gates and stop logs are price competitive with all competitive fiberglass and metal products but offer a vastly superior flow control device and we stand behind the product with the best warranty in the industry! The attention to detail in our product is the result of over 40 years experience supplying gates and stop logs to customers across the globe. For more information on Plasti-Fab gates contact your local representative or view a brochure.