Thousands of companies around the world use chemical storage tanks everyday. Their purpose however, varies greatly depending on the type of industry or material. This post outlines the different types and materials and analyses each of their advantages and disadvantages.
Choosing the correct tank type and the correct material can save businesses time and money. Conversely, choosing the wrong tank or material will mean regular maintenance, rapid deterioration or be fixed in its original location. Most importantly however, this mistake can lead to a leak being created after a few short years. Obviously, a damaged or leaking chemical tank can be extremely dangerous to property, the environment or your staff and customers. It can occur because of corrosion, no maintenance, transportation or installation errors and flaws in the construction or containment. Hence, it is imperative that businesses correctly choose their tank type and material.
The predominant tank type used in Australia is industrial chemical storage. This is due to Australia’s large mining and resource sector and its demand for chemical containment. A typical chemical storage tank can mix, process, store and transport raw materials and chemical products. Such products and materials include wastewater, crude oil, hydrochloric acid, petroleum and propane. The majority of tanks are rectangular or cylindrical but some specialised fabricators offer custom shapes and sizes.
Industrial tanks have several different types and include chemical storage, oil storage, hot water storage, plastic storage as well as water and liquid storage.
There are a number of factors when it comes to choosing a chemical storage tank material.
- Chemical Dosage
- Chemical Combinations
- Weatherability of Containment
- Design Life
- On-going Maintenance
- Price Point
Key factors in the decision making for customers include design life, price point, safety and the type of chemical to be stored inside the tank. Plastic tanks for example are able to store different types of chemicals as opposed to concrete tanks.
Chemical Storage Tank Types
Chemical storage tank materials can be broken down into four key types. These include plastic (Polyethylene, Polypropylene, PVC and PVDF), stainless steel, fiberglass (FRP) and concrete.
Plastic (PE, HDPE, LDPE, XLPE)
Plastic chemical tanks are the most popular material and offer several different types and manufacturing methods. Common types of PE used in tank fabrication are High-Density Polyethylene (HDPE) as well as Polyethylene and LDPE (Low-Density Polyethylene). HDPE advantages include environmental stress cracking resistance, chemical resistance, durability and cost. Similarly, LDPE is chemical resistant, but it also has increased low moisture absorption and impact and stain resistance. Another popular material for chemical storage tanks is Cross-linked Polyethylene (XLPE). XLPE is essentially HDPE that ties bonds and polymers together to enhance its physical properties. The material is exclusively moulded and cannot be welded. Advantages for XLPE include low maintenance, improved toughness, chemical resistance, leak resistance and a longer lifetime. Plastic tanks in general have a longer lifetime than steel and fiberglass due to its technical properties which include superior chemical and corrosion resistance. Polyethylene tanks are also more resistant to leaks compared to other materials. This is because when they are rotomoulded or fabricated, they are moulded into a singular structure without seams. Poly fabrication techniques include CNC machining, rotational moulding (rotomoulding), extrusion, injection moulding, blow moulding, vacuum forming, polymer casting and 3D printing.
Because PE is an all round material, its types and applications vary greatly. Plastic tanks have both domestic and industrial applications such as rainwater collection, chemical storage as well as liquid containment and transportation. Key advantages include
- Versatility for different applications
- Custom sizes available as well as standard cylindrical/rectangular shape
- Material strength
- UV resistant
- Corrosion resistant
- Long service life and low maintenance cost
- Lightweight meaning cheaper freight
Stainless Steel (304, 316, Nickel Alloy, Carbon Steel)
Stainless steel is the second most common type of chemical storage tank. This is because it is corrosion resistant, strong, durable and can be utilised for different applications. There are four main types of stainless steel tanks – 304 Steel, 316 Steel, Nickel Alloy and Carbon Steel. Stainless steel storage tanks are effective however, they are not suitable for some acids and are the most expensive option.
304 Steel is the most popular because of its price and corrosion resistance. It is ideal for construction or food applications. The 316 Steel is almost identical to the 304, except it has a higher resistance to chlorides making it suited for use in coastal regions. Nickel Alloy is very similar to stainless steel but has higher corrosion resistance meaning it is safer for chemical storage and transportation. Carbon Steel is not as shiny as the other types and is not as resistant to corrosion. Carbon Steel will corrode over time unless it is coated (often with Polyurethane) but the coating is not a permanent solution. It also requires regular painting. However, it is cheaper and better for use in non-corrosive applications and out of view locations. Disadvantages of stainless steel include maintenance and more expensive freight (due to heavier weight).
Fiberglass is another popular type of chemical storage tank. It has resistance to rust, corrosion, heat and abrasion. It is also lighter compared to steel or concrete tanks. Fiberglass tanks advantages also include customisation, reliability and easy installation and modification processes. Types of FRP chemical storage tanks include single-wall or bunded, underground, above ground, horizontal or vertical. The capacity for underground storage can reach 500,000 litres while the above ground capacity is 75,000 litres.
Fiberglass tanks are suitable for some applications. However, due to the construction process, a leak may form that will create more maintenance in the future. The tanks are also more prone to human error from the same construction process.
Concrete storage tanks have been used for water and chemical storage for decades. It should be noted though, as technological advancements in the chemical storage industry are made concrete tanks have become less common over the years. This is because concrete does not have the same material properties as stainless steel, plastic or fiberglass. Different types of concrete storage tanks include underground, poured on site and pre-made. Sometimes concrete tanks are requested to be lined with poly in order to mitigate potential leak issues.
The advantages of concrete are its strength, durability and applications in residential and commercial settings. Disadvantages include being susceptible to cracks or leaks, due to steel reinforcement and Lime which is found in concrete, as well as being more difficult to transport due to its weight.
Other less common types of storage tanks are onion tanks, which are self-rising fittings ideal for emergency water storage. Another is pillow (bladder) tanks which are collapsible tanks that can be reused for temporary storage. Steel panel tanks are commonly used for water storage in industrial or rural applications and come in a variety of shapes and sizes.
Overall, these different types of chemical storage tanks have their own advantages and disadvantages. It is important that the customer understands the chemical product inside the tank, the tank’s material properties and its durability. Polyethylene plastic, stainless steel, fiberglass and concrete are all viable options for chemical storage if they are used in the right environment for the correct application. Plastics as a whole offers greater material properties and capabilities compared to other alternatives regarding safety and durability.
For more information on chemical storage tanks, please contact us today via email at [email protected] or call 1300 465 888.