FRP vs PVC Storage Tanks: Which One Should You Choose and Why?
Selecting the appropriate storage tank for your industrial, commercial, or residential purposes is an important consideration when selecting a tank, as it determines the durability, cost-effectiveness, and safety of the tank. Fiberglass Reinforced Plastic (FRP) and Polyvinyl Chloride (PVC) are two of the most commonly compared materials. Although both types of tanks provide numerous benefits, how suitable each will be to you will depend on your unique application. This in-depth article will provide you with all the information you need to better understand the differences between FRP and PVC Storage Tanks, including the advantages, disadvantages, and best uses of FRP and PVC materials for tanks.
Understanding the Materials: FRP and PVC Explained
FRP (Fiberglass Reinforced Plastic) is a composite material made out of a polymer resin with fine strands of glass embedded within it. The strength of both materials together creates an extremely strong and lightweight product that also has corrosion resistance. The process for making FRP tanks involves winding to form seamless walls that are very strong and have a variety of wall thicknesses that can be specified by the user.
PVC stands for Polyvinyl Chloride and is one of the most commonly produced synthetic plastics in the world. PVC is rigid, inexpensive, and resistant to many different chemical substances. Most PVC tanks are produced using either the extrusion or the molding methods, and they have smooth, clean, and non-porous surfaces.
Head-to-Head Comparison: Key Factors to Consider
1. Strength and Durability
Fiberglass Reinforced Plastic (FRP): FRP’s fiberglass reinforcement provides exceptionally high tensile strength (ability to withstand pulling) and impact resistance (ability to withstand forceful contact). FRP tanks exhibit high structural integrity and are designed to withstand some of the worst environmental conditions, such as heat and cold temperature differences, physical stresses, etc. Compared to many plastic tanks, they are less likely to crack under pressure or impact. Under proper care, FRP tanks have an approximate useful life of approximately 20 to over 30 years.
Rigid Polyvinyl Chloride (PVC): While Rigid PVC is considered to provide very good mechanical strength for a thermoplastic material, Rigid PVC cannot achieve the same strength-to-weight ratio as FRP does. PVC will eventually become brittle if exposed to sunlight without some sort of UV inhibitor, and even with a UV inhibitor, PVC will still develop rigidity with time. Therefore, PVC will crack more easily than FRP when subjected to a sharp impact and/or stress. Lifespan varies, but the typical useful life is around 10 to 20 years.
Conclusion: Overall, with respect to both strength and durability required for heavy-duty long-term applications, FRP tanks are the clear choice.
2. Chemical Resistance
FRP, or Fiberglass Reinforced Plastic, has a very broad range of chemical resistance. The specifics of the resin used to build the product can also be chosen to maximize chemical resistance (i.e., vinyl ester, polyester, or epoxy can be chosen for the laminate and resin construction). Therefore, FRP is optimal for the storage of highly corrosive materials, industrial process fluids, and wastewater.
PVC, on the other hand, typically possesses a high level of chemical resistance to many different chemicals, such as acids, alkalis, salts, and alcohols. As a result, PVC is typically the preferred material for many corrosive applications. However, it is not recommended for use with many common solvents, such as aromatic hydrocarbons, ketones, or chlorinated solvents, as these materials can damage or weaken PVC.
Overall, PVC is considered a better option for the storage of common corrosive chemicals, while FRP provides manufacturers with an improved option when storing very unique and challenging chemical materials.
3. Temperature Tolerance
FRP:
In general, the temperature ranges that can be achieved with FRP tanks are much wider than those that FRP tanks can achieve. Most FRP uses a temperature range between -40°F to 180°F (-40°C to 82°C), and many FRP resins offer the ability to exceed these limits. The thermal expansion/contraction properties of FRP are also much less than those of PVC.
PVC Tanks:
The maximum continuous temperature of PVC is typically in the range of about 140°F (60°C). At colder temperatures, PVC becomes more brittle and easily broken due to impact. The coefficient of thermal expansion for PVC is much greater than that of FRP.
4. Cost Considerations
Cost of installation:
PVC tanks are often less expensive than equivalent tanks made of FRP (fibreglass) materials because they are typically cheaper to manufacture than FRP tanks. Thus, if someone is working with a limited budget or has a less demanding requirement and specification, PVC may be a more attractive option.
FRP tanks require a higher initial investment, largely due to a higher material cost and a more intensive manufacturing method.
Cost of ownership over the life cycle:
Although PVC tanks are less costly to install than FRP tanks, in the long run, FRP tanks provide better overall value than PVC tanks. This is primarily due to the extreme durability, long life span, and low maintenance of FRP, which can dramatically lower the total cost of ownership in industrial environments where tanks must be in service for extended periods (i.e., days, weeks, and months) before replacement is necessary. For example, if you need to replace a PVC tank due to failure two times prior to the need to replace an FRP tank, the total cost of ownership will shift significantly.
Conclusion:
PVC tanks will provide the lowest initial investment; FRP tanks will provide the greatest long-term value.
5. Weight and Installation
Fiberglass Reinforced Plastic Tanks (FRP) are a notable alternative to traditional steel/concrete tanks based on their relatively small weight versus the ability to withstand the same amount of pressure as a heavier tank. Because of their lightness, smaller to mid-sized FRP tanks require much less “specialised” equipment to assist with transport/installation/movement than do steel or concrete tanks.
Polyvinyl Chloride (PVC) tanks are also lightweight/easy to handle, but may be easier to move/installation than FRP tanks in smaller sizes.
Conclusion: Because both options are relatively lightweight, PVC tanks will likely have a small advantage over FRP tanks when it comes to installing small (simple, basic) tanks.
6. Maintenance and Repair
FRP tanks do not require extensive maintenance and have a long life span because they do not corrode and can be quickly and easily inspected for performance. In addition, if damage occurs, it is often able to be repaired in the field using a fiberglass repair kit.
Although PVC tanks also require very little maintenance, if they become damaged, it is usually very hard to permanently fix the problem, and often, parts of the tanks may have to be replaced entirely.
Conclusion: FRP has a small edge in terms of its field-repairability, particularly for applications where installation is critical.
Ideal Applications: Where Each Tank Excels
Choose FRP Tanks For:
Chemical Processing / Storing: Things like corrosive acids, alkalis, solvenst and other industrial waste are included.
Water / Wastewater Treatment: Chlorine, Sodium Hypochlorite; Ferric Chloride Storage; Clarifiers.
Pulp and Paper Production: Aggressive Bleaching Chemical(s), Chemicals, and Process Liquids.
Oil & Gas: Produced Water (Water with Oil), Brine; Storage for Mild Chemicals.
Storage of Very Large Amounts of Water: Potable (Drinkable) Water, Firewater (has a long life span), Irrigation (Fit for Irrigation).
Specialized Storage Applications: Food Grade Storage (Used Food-Grade Resin); High Purity Chemicals (Semiconductors), Tanks with Complex Shapes or Structure Supports.
Choose PVC Tanks For:
Chemical Storage Using Less Aggressive Chemical Products: Acids and bases are diluted in conjunction with the chart of compatible industrial chemicals used for storage.
Water Storage & Transport: Water sources can be stored and transported in accordance with Potable (drinking) water, Deionized (absent ions) water, and Rainwater Harvest systems & shall bear an NSF/ANSI Cert #61.
Agricultural Storage and Use: Describe how these tanks will work as not only storage but as a delivery system for fertilization, Irrigated Fields/ Reservoir Storage Tanks/ Animal drinking water.
Residential/Light Commercial Uses: Describe how these tanks will work for pressure tanks, wastewater systems (Septic), and any General Liquid Storage use.
Economic Project Considerations for Applications: Define applications using a combination of Chemical/Physical properties that would classify as a mild chemical environment, along with an initial budget constraint for this application.
The Sustainability Angle
Fibreglass reinforced plastic (FRP) offers a durable and long-lasting material that provides a way of achieving resource efficiency. Recycling of thermoset composites at the end of life has proven to be difficult; however, innovation is occurring in this area for FRP. The long service life of FRP may outweigh its initial environmental impact.
Polyvinyl chloride (PVC) has a recycling capability under Recycling Code #3. Many tanks made from PVC use recycled material in their manufacture. However, given its likely shorter service life in harsh service, a greater likelihood exists for the replacement of waste in the future.
The Bottom Line: Making Your Choice
The choice between these two materials is largely determined by your current needs and circumstances rather than by which one is always “better.”
Select PVC when:
- You need to stay within a lower initial budget.
- Your tank will hold water or mild, compatible chemicals.
- You’re using a tank that is small to medium in size.
- The temperature of the liquid will be moderate.
- You need a basic, standard tank solution for a shorter-duration project.
Select FRP when:
- Your need for a tank is for maximum service life (at least 20 years) and durability.
- You will be using a tank to hold aggressive, specially formulated, or high-purity chemicals.
- You require a tank that is large in dimensions and/or custom-designed/engineered.
- Your application involves extremes in temperature, severe climatic conditions, or high structural load demands.
- Your primary goal is to keep your total lifecycle costs and downtime as low as possible, even though you have made a higher initial investment.
Conclusion
Both FRP and PVC are available as materials for a number of applications. The material that will be most appropriate for a particular use is determined primarily by the specific requirements and priorities of an individual. Applications that call for the use of strong chemicals or high-temperature environments should generally utilize FRP due to its ability to withstand both high temperatures and corrosive chemicals. On the other hand, PVC may be the best choice if you are trying to find an economical storage solution for standard water or mild chemicals (e.g., solutions containing salts). It is important to remember that when selecting a material for use in your application, you need to select based on the fluid being transferred, the environment in which the material will be used, and the operational goals of the company. The selection should not only be based on the initial purchase price but also on subsequent operating costs.