How is Fiberglass Reinforced Plastic Fabricated?

fiberglass reinforced plasticsIn this post, the second of our FRP blog post series, we’re going to cover three of the most common fabrication methods for fiberglass reinforced plastic. The first of which is the most basic:

Hand Lay-Up

This is the most basic of fabrication techniques for fiber-glass-reinforced plastics. Sometimes, it is also referred to as “contact molding.” A simple mold, whether male or female, is used. It is first coated with an appropriate release agent and the layup fabrication is started. The first material applied is normally a 10-mil layer of resin and special corrosion resistant glass called “C-glass”. This reinforcing glass is in the form of a very thin veil or surfacing mat, similar in appearance to the “angel hair” used for Christmas decorations. This first 10-mil layer gives a high-resin, low glass content corrosion barrier.

In the hand-lay-up process, this 10 mil layer is followed by a minimum of two layers of fiberglass in a mat form. This mat consists of chopped glass fibers, randomly oriented, with a binder that holds them into a coarse cloth like form that can be cut, handled and applied. Resin, catalyzed to cure at a predetermined rate, is applied by means of brush or spray gun. The resin is worked into the chopped-glass mat by means of rollers, similar to paint rollers.

When the wall thicknesses are ¼ inch or more, (typically, when past the first two layers of chopped mat), a stronger glass reinforcement is used. This reinforcement is known in the trade as “woven roven,” and consists of continuous glass filament woven in a pattern similar to a coarse cloth. The woven roving reinforcement and chopped mat are put in alternate layers, with the final layer being chopped mat.

Spray Up

This is very similar to hand lay-up, and is also included in the general category of “contact molded” fabrication. Spray up is simply an automated way of depositing the chopped glass. Fabrication still starts with the 10 mils of surfacing vein glass in a continuous fiber form, similar to a thin rope. It is pulled through a gun head that chops it into short lengths and sprays it toward the mold. At the same time, catalyst and resin are sprayed through the gun head. Thus, the catalyst, resin and glass are all deposited at one time. The resulting spray lay-up is rolled to obtain good wet-out of the glass and to remove any entrained or entrapped air. Savings come from a reduction of labor and the use of a lower cost form of glass reinforcement. For heavier laminates, woven roving is still used between alternate layers of chopped glass laminate.

Filament Winding

In this fabrication method, which is primarily applicable to round or cylindrical parts continuous glass fiber, again in the form of a very thin rope, are pulled through a bath of catalyzed resin. In the bath, the glass fibers are thoroughly wetted and the excess resin removed. The resin-impregnated fibers are then wrapped around a rotating mandrel. Typically, this is mounted in a winding machine resembling a lathe. The glass fibers traverse the length of the rotating mandrel, laying the fibers in a predetermined pattern. Typical products that are produced by filament winding include frp pipe of various sizes and large diameter tanks. Depending upon the application, fabrication of the part will start with a number of layers of high-resin-content “C-glass” surfacing mat (usually 20 to 60 mils total), followed by approximately 100 mils of the randomly dispersed chopped fibers, and then followed by the filament winding.

Are There Other Fabrication Options?

Yes, in addition to hand lay-up, spray up, and filament winding there are three other fabrication options; pultrusion, press molding, and centrifugal casting. To learn more about these fiberglass reinforced plastic fabrication techniques, please download our free brochure, “Fiberglass Reinforced Plastics for Corrosion Resistance.”

Smoke Resistance? Fiberglass Reinforced Plastic is Smokin’

fiberglass reinforced plasticsBut seriously, during a fire fiberglass reinforced plastic does create smoke.  As we mentioned in a previous blog post, new regulations and code requirements regulating smoke toxicity have made smoke an important consideration, for some.

Why Is Smoke A Concern?

Personnel safety is the main reason why smoke is a concern in service environments. Smoke can present a personnel safety hazard for two reasons:

1. Heavy dense smoke cannot only make breathing difficult, but can obscure the escape paths when people are trying to escape from a building during a fire.

2. Smoke toxicity, especially from organic materials, is also a critical safety consideration. Even if the smoke is very light, but is highly toxic, personal injuries can occur.

Smoke toxicity is one of the reasons the New York City and New York State Fire Marshals have now added to their code requirement consideration for low smoke toxicity.

Is Smoke An Important Building Factor?

Whether smoke is an important factor in your construction is really dependent on your unique requirements. However, rather than deciding to spend a lot of time and energy trying to develop low smoke alternative, you really should try to determine if low smoke is really important in your service environment. If your tank, piping, or duct application is mostly outdoors in an industrial location, then perhaps smoke is of only minor importance. In cases where this is the case, if you are going to have a major plant fire, the smoke generated probably is the least of anyone’s worries. Likewise, in many service installations where there is low “people occupancy”, such as water and waste treatment facilities, composting facilities, warehousing buildings, etc., then again, low smoke is perhaps only of secondary importance.

Deciding whether fire retardancy (low flame spread), smoke generation, or smoke toxicity are even important or necessary for your application should be your first step in determining if smoke is an important building factor. These features are going to cost you extra money. If they are not required, do not specify them. Well over 90% of all FRP composite pipe and duct installed to date is not fire retardant and does not provide low smoke generation and low smoke toxicity properties.

When choosing and specifying the materials for your system, consider the cost of the materials, installation and, most importantly, long-term operating costs. Installation of a Factory Mutual approved system may provide lower insurance rates. However, such a system may also cost more in materials and labor, and may require replacement or repairs in half the time when compared to a properly constructed dual laminate system.

If smoke generation, smoke toxicity and smoke resistance are important to your project, then we recommend that you select the internal barrier/liner of your duct or pipe based upon the best resin matrix for your service environment.

What is FRP?

fiberglass reinforced plasticFiberglass reinforced plastic is not only versatile, but also offers a wide range of practical and environmental benefits. The ins and outs of FRP have given rise to a lot of questions over the years, so we’ve put together a short series of blog posts to cover some of the basics of FRP. Starting with…

What is FRP?

The term FRP, which is common throughout the industry, refers to plastic that has been reinforced with glass fibers. Fiberglass reinforced plastics (FRP) are used for many varied applications; from boats and bathtubs to missiles. However, examples of equipment currently fabricated out of fiberglass-reinforced plastics include FRP tanks and vesselsFRP pipe, FRP ductwork hoods, fans, scrubbers, stacks, grating, and specialty fabrications. One of the fastest growing areas is the use of FRP for pollution-control equipment.

What Can Be Used to Reinforce the Plastic?

Many reinforcements can be used for plastic materials-including polyester fibers, carbon fibers and, of course, glass fibers. For corrosion-resistant equipment, approximately 95% of the applications normally involve the use of glass fibers (with some polyester fibers being used on certain specific occasions.).

What Resins Are Typically Used?

Glass fibers can be added to virtually all of the thermosplastic and thermoset resins, For corrosion resistant equipment, the resins used are primarily those of the thermosetting type. These are resins that, once they have “hardened,” remain in their cured configuration when subjected to heat-up to their distortion temperature or the temperature at which they will degrade. Examples of thermoset resins include the epoxies, polyesters, vinyl-esters, and furan. There are other thermo- setting materials, but these four are used in the vast majority of applications for fiber-glass reinforced plastics. The term “polyester” is a generic one that refers to a wide range of materials. It can include everything from a general-purpose resin used in boats and bathtubs to the most exotic, high-temperature corrosion resins. For corrosion-resistant equipment, specialized corrosion-resistant-grade resins are available.

A number of companies manufacture isophthalic polyester resins, which have a distinct place in the hierarchy of corrosion-resistant materials. Very frequently, to reduce costs, a customer will have equipment built with one of the premium-grade resins used for the corrosion inner liner, the balance of the structural laminate being built with an isophthalic polyester resin.

One type of corrosion-resistant resin in use is the vinylester resin. The vinyl-esters are similar in corrosion resistance to the bisphenol A polyester resins, but for many applications, possess improved physical properties, especially impact and toughness.

The original vinyl-ester resin from Dow was known as Derakane 411. This is a very good resin up to 180°F, but the physical properties fall off very rapidly past that point.

Several years ago, Dow introduced Derakane 470 resin, with improved high-temperature properties and improved solvent resistance. Another addition from Dow has been Derakane 510, a fire-retardant vinyl-ester resin. This resin achieves its fire-retardancy without use of such materials as antimony trioxide.

FRP Fire Resistance: Fiberglass Reinforced Plastic and Fires

No one wants to have a fire in their building or business, but what if you do? How will materials made from fiberglass reinforced plastic react? What about FRP fire resistance? With new regulations and code requirements regulating smoke toxicity, like those in New York City, the amount of smoke created in a fire is also something a lot of builders are keeping in mind these days. So,

What Do You Need to Know About FRP and Fires?

While the fiberglass reinforcements used in corrosion resistant laminates will not burn, most thermoset resins used as the matrix for “FRP” laminates will support combustion. Even the “fire retardant” resins will burn vigorously when fire is supported by an outside source. The rate of flame spread is somewhat lower for these fire retardant resins. Fire retardant thermoset resins typically contain halogens or bromine molecules. When combustion occurs, these additives suppress or smother the flame and the laminate becomes self-extinguishing.

What About Smoke?                                                                               

When the more common thermoset resins (polyesters, epoxies, vinyl esters, etc.) used for fiberglass reinforced plastic composites burn, large amounts of heavy, black, dense smoke can be generated. The carbon chains in these resins contribute to that smoke. There is no difference in the density of the smoke generated between a non-fire retardant resin and a fire retardant resin. The only difference is that the amount of smoke may be less when fire retardant resins are used, and the fire is not supported by an external source.

Although some facilities can experience more damage from the smoke rather than the actual fire, such as in electronics plants, for most facilities the fire itself, and the damage it can cause, is of far greater concern than smoke. As one plant engineer of a major chemical plant told us one time, “When we have a fire in a chemical plant, we are allowed to have smoke.” In those cases of typically wide-open spaces, or facilities with low occupancy, the smoke generated is the least of the problems when a chemical plant or refinery catches on fire.

How Much Smoke Will Be Generated?

ASTM E-84 test results for polyesters, vinyl esters, and epoxies typically yield smoke generation values in excess of “750”. It can be said unequivocally that if FRP composite pipe and FRP ductwork is exposed to a “raging fire”, there will be a lot of smoke generated. The ASTM test can only provide a hint of how much smoke.

Inquiries to all of the major manufacturers of resin systems used for corrosion resistant applications have solicited written responses that they have no, and know of no, polyester and vinyl ester thermoset resin systems that will generate, by themselves, smoke generation values under 350. If you are going to be specifying flame spread and smoke generation levels, we recommend that you consult with either a knowledgeable fabricator, or one of the resin manufacturers.

If you want to learn more about fiberglass reinforced plastic and smoke, please download our “Smoke and Fiberglass Reinforced Plastic Components.”

The Storage of Sulfuric Acid in FRP Composite Tanks

Sulfuric acid (H2SO4) is a chemical that presents unique handling and storage problems. In the higher concentration ranges (96% to 97%), sulfuric acid (66Be’) can be stored in cast iron or carbon steel.  High concentrations of sulphuric acid, however, are very detrimental to FRP composite equipment. At these higher concentrations, sulfuric acid must not come in contact with FRP laminates.

Diluted sulfuric acid, on the other hand, is very aggressive toward cast iron or steel tanks, but can be stored and handled very well in FRP composite equipment. FRP composite equipment is best suited for concentrations of 70% sulfuric acid and below. At 75% sulfuric acid, the maximum temperature allowed with vinyl ester resins is 100° to 120°F. As the concentration decreases, the allowable temperature limits increase.

The procedure for dilution of concentrated sulphuric acid that has worked best in fiberglass composite vessels is as follows:

1. First, add to the storage vessel the entire amount of water required to achieve the desired solution concentration.

2. Then add the concentrated acid slowly into the center of tank by using one of the following suggested fittings:
a) an FRP top nozzle with a PVC flanged down pipe.
b) a PVC coupling and down pipe.
c) a 316 stainless steel coupling with a 316 stainless steel down pipe. The reason the concentrated sulfuric acid is added to the tank center is to prevent concentrated acid from coming in contact with an FRP composite nozzle, or sidewalls of the tank. The concentrated acid should not be allowed to drop onto the liquid surface. Introduce the concentrated sulfuric acid 2” to 3” below the liquid surface. One method of accomplishing this is to create vortex by adding baffles from the bottom of the tank to the height that concentrated acid is first added to the tank. Another alternate method is to extend the down pipe 6” below
the liquid surface.

3. During the dilution process, the mixture must be continually agitated to insure adequate dilution and prevent high concentrations of sulfuric acid from settling and damaging the FRP composite tank. To insure adequate dilution, a rubber-coated agitator, or pumping the tank continuously through a side bottom drain,is required. Circulation through any nozzle on the tank bottom could result in heavy viscous concentrated acid settling to the tank bottom and destroying the FRP composite tank below the nozzle.

4. The dilution of sulfuric acid generates considerable amounts of heat. The temperature of the diluted sulfuric acid must be controlled below 150°F for finished concentrations of 50% or less, and 140°F for 50-70% sulfuric acid solutions. This can be accomplished by regulating the flow rate of concentrated sulfuric acid addition, or by external cooling of the tank contents.

5. The preferred type of FRP composite vessel for storing sulfuric acid is a non-insulated, vertical, above ground tank. Even underground tanks, with the ground acting as an insulator, may have excessive storage temperatures.

6. Sulfuric acid (H2SO4) with trace organic impurities can cause reduced service life of FRP composite laminates.

Contact us today about your fiberglass pipe and fiberglass tank requirements.

How to Properly Bury Fiberglass Piping

Beetle Plastics has developed a series of specifications that pertain to buried flexible fiberglass piping where the fiberglass pipe, trench walls, and bedding material work together to form a complete pipe support system. This post outlines the sections covered in our engineering document available for download.

The elements of this system can best be defined by considering a section of buried flexible pipe and the loads acting on it. These loads, the dead load (backfill) and the live loads (vehicle traffic), act downward on the pipe, tending to deflect it into an oval shape. If the bedding material at the sides of the pipe is compacted sufficiently, it will resist the pipe movement and minimize the deflection and ovalization to an acceptable amount. For this reason, the construction of the trench and selection of bedding materials must be closely controlled.

These specifications cover the burial techniques required for the installation of fiberglass pipe under most conditions.

SECTION I: Fiberglass Pipe Storage and Handling

When storing fiberglass pipe directly on the ground, select a flat area free of rocks and other debris that could damage the pipe. Also, when preparing the ends for joining (butt wrap or tapered bell and spigot joints), do not roll the pipe over rocks, debris, or uneven ground that does not fully support the pipe.

SECTION II: Trench Excavation and Preparation

The actual depth of the trench is determined by the final grade, plus the depth required for the initial (bottom) layer of bedding material. The soil conditions and bedding materials being used will determine this additional depth.

Nominal trench widths are listed in the engineering guide available for download.

SECTION III: Bedding and Backfilling

The trench bottom is the first element of the pipe support system. There are many things to consider when building the bedding including pipe diameter, pipe type, soil type and density, and water table.

Schematics and details are contained in the fiberglass pipe engineering document.

SECTION IV: Concrete Structure

Where the fiberglass piping goes through or passes under a concrete structure, precautions must be taken to prevent excessive strain on the pipe due to the differential settling between the structure and the pipe. There are several methods discussed in the engineering document for compensating for settling without straining the fiberglass pipe.

Contact us today about your fiberglass pipe and tank requirements.

Fiberglass Pipe Thermal Expansion and Contraction

frp material properties, frp pipe

FRP Pipe Properties: Thermal Expansion and Contraction

Beetle Plastics fiberglass pipe is filament wound and, therefore, has different thermal expansion in the hoop and axial direction. In the hoop direction, the thermal expansion is about the same as steel. However, in the axial direction, the thermal expansion of the fiberglass pipe is about twice that of steel.

The relatively low modulus of elasticity of the fiberglass pipe is an advantage which should be considered in the design of a piping system. Since thermal forces are smaller, restraining equipment (guides, anchors, etc.) need not be as strong or heavy as for steel piping. There is some growth due to end load from pressure in the piping system; but experience has shown that this length change does not need to be considered in designing a fiberglass piping system. FRP composite piping systems can handle thermal shocks between maximum rated operating temperatures and -40°F, unless the pipe joints are mechanical joint style.

To determine the effects of expansion and contraction within a piping system, it is necessary to know:

  1. The design temperature conditions.
  2. The type and size of pipe.
  3. The layout of the system including dimensions and the thermal movements, if any, of the terminal
  4. points.
  5. The limitations on end reactions at terminal points as established by equipment manufacturers.
  6. The temperature changes for expansion are calculated by subtracting the installation temperature (temperature at time of final tie in) from the maximum design temperature.

Temperature changesfor contraction are calculated by subtracting the minimum design temperature from the installation temperature. Expansion and contractions of above ground fiberglass pipe may be handled by several different methods.

Four methods are:

  1. Direction Changes
  2. Anchors and Guides
  3. Mechanical Expansion Joints
  4. Expansion Loops

Guides, Expansion Loops, and Mechanical Expansion Joints are installed in straight pipelines which are anchored at both ends. The experience of users of FRP composite piping systems has shown that if directional changes cannot be used to accommodate thermal expansion and contraction, then the guide spacing design approach is usually the most economical method.

Operating experience with piping systems indicates that it is a good practice to anchor long straight pipe runs of above group piping at approximately 300-foot intervals. These anchors prevent pipe movement due to vibration, water hammer, etc.. Also, an anchor is used wherever a pipe size change occurs. When joining FRP composite piping to other piping systems, the adjoining system MUST be securely anchored to prevent the transfer of thermal end loads.

Contact us today and we can arrange a test installation in your plant comparing Beetle Plastics abrasion resistant pipe with your current piping and duct materials.

FRP and Abrasion Resistant Lining: Lined Pipe vs. Unlined Pipe

abrasion resistant lining

This is the second in a series of blog posts discussing lined FRP pipe vs. unlined FRP pipe. The first posts discusses corrosion resistance.

In this post, we discuss abrasion resistance.

Abrasion Resistance: There is an element of abrasive wear in almost all fluid service applications.  In the concern for corrosion resistance, this abrasion element of the environment is often overlooked.  Especially for pipe subjected to high flows or where there may be particulate matter contamination (i.e. cooling water applications, river water, waste handling, etc.) abrasion design needs to be considered for all FRP pipe.

As with corrosion resistance, the resin matrix provides the abrasion resistance.  With a properly designed and selected corrosion barrier/liner, the abrasion resistance (and the pipe life) can be up to ten times greater than for unlined pipe, where the glass filaments are directly exposed to the service wear.  With unlined pipe, very rapid wear can occur, with the roving filaments being “picked” away from the surface.

Through further modifications of the corrosion barrier/liner, consisting of proper resin
selection, proper type of non-glass reinforcement, and armoring modifiers, the abrasion resistance of the corrosion barrier can be further improved.

Another compelling reason for always using a corrosion barrier/liner in FRP composite pipe is to provide the capability for changes in service environment. Even if the current service environment would not benefit from the additional protection of a corrosion barrier/liner, the addition of a corrosion barrier/liner provides insurance that future changes in the service stream can take place without concern for the life of the FRP pipe.

Perhaps the nature of the waste stream may be different five or ten years from today. Perhaps even for relatively mild cooling water or river water service, the end user may want to add treatment chemicals in the future. The zebra mussel that is attaching itself to the insides of pipe has made headlines.

The addition of a corrosion barrier/liner for pipe would provide additional abrasion resistance in removing, by mechanical means or hydro blasting, such mussel buildups.  The small additional cost for a corrosion barrier/liner can be a very inexpensive insurance policy for the future. 

The final benefit to using lined FRP composite pipe is lower in-service costs.  One of the advantages of FRP composite plastic pipe is its internal smoothness over its entire service life, especially when compared to other materials such as concrete, steel, etc.  This smoothness is translated into less friction and, thus, lower pumping cost. In some cases, even a smaller diameter pipe can be used.

Even small differences in the smoothness of the FRP pipe interior can be translated into dollar savings in electricity or fuel (for the pumps). The glass smoothness of the high resin content corrosion barrier/liner is measurably better than for unlined FRP pipe. In addition, the energy savings advantage of the resin-rich corrosion barrier/liner increases with age.


Except for conduit, in almost all instances a corrosion barrier/liner can be economically justified for FRP composite pipe. We recommend, as a minimum, a 40 mil thick C-veil and/or Nexus reinforced corrosion barrier/liner. For moderate and severe corrosive environments, an even thicker corrosion barrier/liner should be considered.

We will be glad to work with you in selecting the best corrosion barrier/liner for their service
environment.  We are confident that “lined” FRP pipe will provide the end user their lowest cost per year of service life and, thus, their “Best Buy”.

Contact us today and we can arrange a test installation in your plant comparing Beetle Plastics abrasion resistant composite FRP pipe with your current piping and duct materials.

Improvements to Abrasion Resistant Pipe made from FRP Composites

abrasion resistant pipeJack Mallinson of FMC Corporation’s plant in Front Royal, Virginia, working in conjunction with Beetle Plastics, then located in Fall River, Massachusetts, conducted some of the earliest work in improving abrasion resistance of FRP pipe. These original developments took place
in the late 1960’s and early 1970’s.

This work found that significant increases in abrasion resistance could be achieved by adding armoring modifiers to the resin used for the internal corrosion barrier of the pipe. In those early days, the best modifiers were various forms and grades of aluminum oxides. There were problems in getting the aluminum oxide to disperse and “wet out”. However, once the aluminum oxide dispersed, improvements of abrasion life in the magnitude of two to three times over a non-modifi ed resin were achieved. The resin matrix used in those days was typically the Hetron 197 polyester resin.

While some companies that make so-called abrasion resistant pipe still use that same filler approach and formulation from the late 1960’s, Beetle continued to find a better way. In the early 1970’s, working with the late Walt Szymanski of Hooker Chemical, Beetle Plastics made major advances in the technology of abrasion resistance in FRP composites. In an extensive series of tests conducted in conjunction with Hooker, Beetle discovered that three fabrication techniques significantly influence the resulting abrasion resistance of the composite laminate.

Type of Resin: The type of resin used in making the inner abrasion/corrosion liner of the pipe influences the resulting abrasion resistance of the pipe. Special developmental elastomeric and epoxy vinyl ester resins signifi cantly increase the abrasion service life. Beetle Plastics
worked closely with Dow Chemical and Interplastics in developing these experimental resins. The selection of the proper resin, along with specifi c resin modifi cations, increases abrasion resistance by a factor of two to three times over a standard polyester or epoxy resin.

Type of Reinforcement: Beetle also discovered, in these series of Hooker tests, that the type of reinforcements used in the matrix signifi cantly infl uenced the abrasion resistance of the inner abrasion/corrosion liner. The tests demonstrated that specific types of
reinforcements greatly improved abrasion resistance of the laminate.

Also, a specific combination of selected reinforcements was critical to obtaining the optimum abrasion resistance. As the result of that knowledge, Beetle Plastics now uses a unique combination of laminate reinforcements that help significantly improve the total abrasion resistance of the composite laminate.

Armoring Modifier: Building on the early work done with FMC, Beetle conducted extensive tests to improve armoring modifiers. Beetle succeeded in developing a new type of modifier that provides superior armoring of the FRP composite. This material compares in toughness to
basalt, which in its natural form is often used as abrasion liners for steel pipe.

Over the years, Beetle Plastics has fine-tuned the specific grades of this armoring modifier material, selecting those that demonstrate the best performance in abrasion resistant FRP composite pipe. Beetle also developed techniques to gain the optimum dispersion and wetting out of this armoring modifier within the resin. Getting this ideal resin “hook” to the armoring modifier is also an important consideration when developing the best possible abrasion resistance of FRP laminates.

In order to gain maximum abrasion resistance from FRP composite pipe and laminates, it takes careful selection of all three of the important factors (resin, reinforcements, and armoring modifiers), in the proper ratios and interactions.  Test results from this research indicate reductions in abrasion loss in FRP composite laminates to just one-tenth that of non-modified laminates. In other words, you might expect increased service life of ten times, or more, from Beetle Plastics abrasion resistant composite pipe and ducts.

But, to paraphrase an old saying – “the proof is in the pudding”. For FRP composite abrasion resistant pipe, the proof is in the service life obtained in actual fi eld installations.

In tests, control installations showed substantial abrasion wear and failure in just several months of service life. Regular six-month and annual inspections at these plants of Beetle Plastics abrasion resistant pipe and elbows (an elbow is an area of high abrasive wear) showed little discernable wear.

Beetle continues to refine our FRP pipe abrasion resistant technology. As a result, you can confidently turn to Beetle Plastics for the best FRP composite abrasion resistant piping system available.

Customers at numerous projects have achieved outstanding FRP piping service life in highly abrasive applications such as lime slurry, fly ash slurries, and the extremely abrasive bottom ash service.

Contact us today and we can arrange a test installation in your plant comparing Beetle Plastics abrasion resistant pipe with your current piping and duct materials.

Lined Pipe vs. Unlined Pipe – Pipe Strength and Structural Integrity

lined pipe vs. unlined pipeIn earlier posts, we discussed the first reason to choose lined FRP pipe: abrasion resistance and corrosion resistance. The third major reason to choose Lined FRP pipe is Structural Integrity.  While typically the corrosion barrier/liner is not counted on for adding strength to the FRP pipe, it does enhance the structural integrity.  Depending upon the service environment, sometimes the structural properties of the SPI type corrosion barrier/liner are included in determining the pressure rating of the FRP pipe.

One of the advantages of properly designed and manufactured fiberglass filament wound composite pipe is that it will typically show signs of “weeping” through the pipe wall when over-pressurized, long before a catastrophic failure occurs.  Such weeping occurs by fluid wicking following the continuous glass roving used in filament winding.  The weakest portion of the structural wall is the glass/resin interface. The corrosion barrier/liner, thus, serves to prevent the fluid media from getting to that continuous fiberglass filament.

From a purely structural viewpoint, the ideal corrosion barrier/liner would be a rubber bag. This rubber liner would continue to stretch, allowing the structural wall to fully take advantage of the superstrong, continuous glass filaments until they actually broke.  A properly designed resin corrosion barrier/liner serves the same function allowing the structural wall to take the full load without concern for pipe wall weeping.

Contact us today and we can arrange a test installation in your plant comparing Beetle Plastics abrasion resistant composite FRP pipe with your current piping and duct materials.