What is FRP?

FRP standsare initials for Fiberglass Reinforced Plastics.

FRP is a composite material made of a fiberglass-reinforced plastic thermostable resin matrix. In Peru, this product is usually called "Fiberglass", while in other countries of the region it receives the name of “Reinforced Plastic.

The plastic matrix provides chemical resistance and may be made of different types including Ortoftalic resin, Isoftalic resin, Epoxi Vinylester, etc.

The fiberglass adds mechanical resistance to the resin. This highly resistant reinforcement gives the composite the required stiffness and stability.

Yes. It is possible to manufacture large, one-piece molded FRP products without using internal metallic reinforcement.

Like other materials, FRP has defined mechanical, physical, and chemical properties according to its composition. Therefore, the correct design of these products is what makes them safe and reliable when they undergo extreme mechanical loads.

In some cases, FRP is reinforced with stiffening elements or steel accessories. This is not due to FRP's failure to resist overloads, but to specific improvements in the technical-economic balance of the product. That is the case of grommets, rings, support columns, anchoring devices, etc.

Can ladders, railings, or other kind of accessories be attached to FRP pieces?

Accessories may be attached to tanks. FRP is very flexible in terms of product shape and such accessories as ladders, railings, tank manways, tank fittings for agitator shafts, piping supports, etc, can be attached.

Yes, It is possible to bind metallic and other kinds of accessories as long as the appropriate design and manufacturing technology are used.

It must be noted, however, that metals and the majority of thermoplastics do not have chemical affinity to FRP, therefore, it is not a matter of just “sticking” an accessory to the tank.

There are well-established design, calculation and application standards and procedures issued by organizations and institutes specialized in FRP.

Since most of the chemical resistance of FRP comes from the resin (plastic matrix) component, manufacturers worldwide publish a “Chemical Resistance Chart” of their products, which is consistent with the kind of fluid to be stored, its gravimetric concentration, the maximum work temperature, plus other considerations (pH, impurity concentration, phase, etc.).

These charts, used by FRP manufacturers and specialists, show product's resistance to different kinds of fluids. Nevertheless, it should be noted that despite resin being the main component for chemical resistance, the fiberglass or reinforcement must be properly selected based on compatibility with the resin and the fluid to be stored.

The maximum work temperature to which FRP can be exposed depends on the resin's resistance to the different types of fluids to be stored or transported as indicated in the Chemical Resistance Chart mentioned on FAQ 5.

As a general reference, though, FRP can undergo work temperatures as low as -20°C, and a max. temperature of 200°C depending on the fluid or gas.

The maximum work pressure depends on design. Nevertheless, there are certain size limitations in the case of pressurized equipment. For this reason, it is advisable to strike a technical balance between the size of the equipment and the pressure it will undergo. This means that small pieces such as a 2” pipeline can undergo very high pressures (3000 psi approx.) while for wide-diameter equiment pressures of no more than 15 psi are recommended to avoid a disruption of the technical-economic balance.

In some particular situations, it is recommended to apply a coating to encase a steel or concrete tank in FRP instead of molding a tank in FRP. These situation include:

In all the above situations, the technical-economic balance suggests the use of FRP coating. FRP coating can also work for other other particular cases.

However, the difference between the thermal expansion rates of steel and FRP, and of concrete and FRP, restricts the use of FRP coating to equipment that operate at temperatures below 80° C - 100 ° C, and calls for an analysis of the specific application for temperatures above 60° C.

In all situations, special care must be taken in the preparation of the base layer for proper adherence.

Unlike the majority of thermoplastics, FRP shows a high UV light stability. There may be some changes in the physical appearance of the equipment (e.g. color), but minimal changes in its mechanical properties.
Since a wide variety of UV light inhibitors are available and should be added to the top coat of the equipment.

The widely spread applications of FRP are due to its high flexibility as a manufacturing material. This characteristic also makes the repair of FRP equipment easier.
It is necessary to assess the damages first since the repairs might not be economically viable or technically advisble.
It should be considered that when a piece of equipment gets damaged during operation, it should be put out of service, emptied, and the work site must be prepared for the fixings.

Like any other material, FRP products comply design standards, such as ASTM, ASME, BSI, etc. These standards determine the thickness of each part of the equipment, including the body, lid, bottom and accessories of the tank.

The design will also depend on the kind of fluid to be stored, the place where the tank will operate (seismic zones, strong wind zones, heavy snow zones, etc.), the work temperature, etc. It is also possible to design tanks that are thicker at those parts where extra resistance is needed, in order to make the tank lighter.

Therefore, it is not possible to establish a standard thickness for all kinds of tanks.

As with many other plastics, the vibration and shock absorption properties of FRP are determined by its elastic modulus. The elasticity and high mechanical resistance of FRP make it a highly shock resistant material for structural laminates.

For corrosion resistant equipment, a shock or impact may not damage the structure, but the chemical barrier should be carefully inspected before the repair work is started.

One of the main advantages of FRP is its light weight when compared to metallic materials, including aluminum. FRP's density ranges between 1450 y 1800 Kg/m3, against 7800Kg/m3 for steel.

Despite of steel's higher mechanical resistance and stiffness, FRP's weight-resistance rate is better compared to steel.

In some cases, the equipment's top coat may be treated, any deposits on the equipment internal walls must be removed, or damage caused by external factors should be repaired. Beyond that, FRP equipment does not require any other type of maintenance procedure.

The useful life of FRP equipment is hard to estimate, since it depends on the kind of fluid stored, the work conditions, the equipment design, and the manufacturing process. Some resin manufacturers perform tests using with different fluids with an estimated extrapolation of 50 years. The test results are shown in the “Chemical Resistance Chart”.
There are many records of FRP equipment built around the world which provide a great deal of information about FRP performance.