GRP tanks (Fiber reinforced plastic) are used in a variety of domestic and commercial applications, including chemical storage in laboratories, agricultural storage for farmers, and in the food and beverage industry. As an effective storage solution, GRP tanks are well protected from deterioration of their contents due to temperature changes and harmful chemicals. The reliability of these tanks is mainly due to the materials they are made of. FRP, also known as GRP and fiberglass, is a fiber-reinforced polymer known for its strength and low production costs, making it a very reliable long-term storage solution.

Here we will outline some of the very beneficial properties of GRP and why it is the best material for manufacturing storage containers.

Corrosion resistance

GRP is highly resistant to corrosion, making it an ideal material for storing chemicals and other substances. Because of its corrosion resistance, bacteria are much less likely to accumulate inside a GRP tank, which means the contents will be kept in optimal condition. It is also able to withstand harsh conditions, so your tank can be left outdoors without being damaged by the sun. 

Low maintenance

Because it won't rust or rot, fiberglass is a very low-maintenance material, making it ideal for creating water tanks. It also doesn't require any painting or surface treatment, so it's very useful for those who can't prioritize the maintenance of water tanks made from materials like wood or metal.

Strong and durable

Despite its lightness, GRP is a very strong and durable material, as are most metallic materials such as steel. In addition to being resistant to corrosion, GRP is also highly resistant to temperature extremes, UV rays and chemicals, making it a very reliable and long-lasting material that is guaranteed to last

Versatile

GRP can be easily molded and shaped, making it a very popular material for a range of different applications. This means that any custom requirements you may have for a GRP water tank can be easily met, as almost any shape or size can be achieved with FRP.

Low production costs

The production cost of manufacturing GRP water tanks is very affordable due to the ease with which GRP can be produced, manufactured and shaped. In addition to this, GRP is a very light material, which means that transporting these tanks requires hardly any additional costs, as they can be transported from the production site to the customer without the need for heavy lifting equipment.

Double-layered panels

Due to the corrosion resistant properties of FRP, the tank can be made entirely of composite material or a second liner can be used. In either case, the liner is made using material properties different from those of the structural part (hence the terms double (meaning two) and laminate (a word usually used for composite layers)).

In the case of liners made of FRP, they are usually resin-rich and use a different type of glass, called "C-glass", while the structural part uses "E-glass". Thermoplastic liners are typically 2.3 mm thick (100 mils). This thermoplastic liner is not considered to contribute to mechanical strength. The FRP liner is usually cured before proceeding to winding or lay-up, either by using a BPO/DMA system or by using a MEKP catalyst with cobalt in the resin.

If the liner is not made of FRP, there are a variety of thermoplastic lining options. The engineer needs to design the tank according to the chemical corrosion requirements of the equipment. PP, PVC, PTFE, ECTFE, ETFE, FEP, CPVC, PVDF are the commonly used thermoplastic liners.

Because of FRP's weakness to flexure but great strength to tensile forces and corrosion resistance, hydrostatic tanks are a logical application for this composite material. The tanks are designed to withstand the required hydrostatic forces by positioning the fibers in the tangential direction. This increases the ring strength and gives the tank an isotropic strength higher than steel (per pound).

The FRP constructed on the liner provides the structural strength required to withstand design conditions such as internal pressure or vacuum, hydrostatic loads, seismic loads (including liquid shaking), wind loads, regenerative hydrostatic loads, and even snow loads.

Applications

FRP tanks and vessels designed to BS 4994 are used in a wide range of applications in the chemical industry in the following areas: chlor-alkali manufacturers, fertilizers, wood pulp and paper, metal extraction, refining, electroplating, brine, vinegar, food processing, and air pollution control equipment, particularly in municipal wastewater treatment plants and water treatment plants.

Types

FRP tanks and process vessels are used in a variety of commercial and industrial applications including chemical, water and wastewater, food and beverage, mining and metals, power, energy, and high purity applications.

Scrubbers

FRP scrubbers are used to wash liquids. In air pollution control technology, there are three types of scrubbers, dry media, wet media and biological.

Dry Media

Dry media typically involves a dry solid media (such as activated carbon) suspended on a system of beam supports and grids in the middle of the vessel. The media controls the concentration of contaminants entering the gas by adsorption and absorption.

These vessels have several design limitations. They must be designed to:

Unloading and reloading of the media
Corrosive effects of the liquid to be handled
Internal and external pressures
Environmental loads
Support loads of fences and support systems
Lifting and installation of the vessel
Regeneration of the medium inside the vessel
Internal stack support for double bed structures
Redundancy for preventive maintenance
De-misting to remove liquids that degrade the dry media
Condensate removal to remove any liquid that condenses inside the vessel

Wet media

Wet media scrubbers typically pour contaminated liquids in a scrubbing solution. These vessels must be designed to meet more stringent standards. Design limitations for wet media scrubbers typically include:

Corrosive effects of contaminated liquids and scrubbing solutions.
High pressure and loading of the spray system
Aerodynamics of the internal media to ensure no bypass
Internal support system
Reservoir of scrubbing fluid for recirculation.
Internal and external pressures
Environmental loads
Lifting and installation of the vessel
Piping of scrubbing fluid to the vessel
Drainage to remove the liquid from the vessel
In a decarbonizer used to limit the concentration of gas in water in a reverse osmosis system, the air is the scrubbing fluid and the sprayed liquid is the contaminated water stream. As the water is sprayed out of the scrubber, the air strips the gas from the water and treats it in another vessel.

Bio

A biological scrubber is structurally identical to a wet media scrubber, but differs in design. The vessel is designed to be larger, so the air moves more slowly through the vessel. The media is designed to encourage biological growth, and the water sprayed across the vessel is filled with nutrients to encourage bacterial growth. In this scrubber, the bacteria scrub the contaminants. Also, instead of a single large support system (chemical scrubbers typically have a media depth of 10 feet), there are multiple stages of media support, which can vary the design requirements of the vessel. See Biofiltration for details.

Tanks

A typical storage tank made of FRP has an inlet, an outlet, a vent, an access port, a drain, and an overflow nozzle. However, there are other features that can be included in the tank. Ladders on the outside allow for easy access to the roof for loading. The vessel must be designed to withstand the load of someone standing on these ladders, and even withstand a person standing on the roof. Sloped bottoms allow for easier draining. Level gauges allow someone to accurately read the liquid level in the tank. The vessel must be resistant to the corrosive nature of the fluid it contains. Typically, these vessels have a secondary containment structure, in case the vessel bursts.

Size

The size of FRP Vessels is rarely limited by manufacturing technology, but rather by economics. Tanks smaller than 7,500 liters (2,000 gallons) are easily manufactured out of cheaper materials, such as HDPE or PVC. Tanks larger than four meters are generally limited by shipping constraints, and the economics suggest a concrete or steel tank fabricated at the tank's location.

For chemical storage and air pollution control, the choice is to make multiple tanks of smaller diameters. For example, one of the largest odor control projects in California, the Orange County Sanitation District will utilize 24 vessels total to treat 188,300 cfm (86,200 L/s) of odorous air, with a design of up to 50 ppm of hydrogen sulfide. For an equivalent single vessel to perform as well as the 13 headworks trickling filters, the single vessel would have to be over 36 feet in diameter. This would be impractical due to the high shipping requirements, internal supports, spray nozzles and other internals. Plus this single vessel would not incorporate redundancy for preventive maintenance.

Design standards

Fiberglass Tanks fall under regulation of several groups.

Bs4994-87 is the British Standards Standard for FRP Tanks and Vessels superseded by EN 13121.
EN 13121
ASME RTP-1 (Reinforced Thermoset Plastic Corrosion Resistant Equipment) is the standard for FRP tanks and vessels held within the United States under 15 psig and located partially or fully above ground.

Get in touch!

At Yongchang, we provide our customers with high quality GRP one-piece water tanks to meet all their needs. Our tanks are also available pre-insulated to protect their contents from extreme temperatures, and we can also manufacture specialized tanks to store chemicals if you need them. All of our tanks are fully tested and approved to meet current water regulations, making them completely reliable and ready for use upon delivery.

For more information or to receive a quote for our GRP water tanks, please feel free to contact us.