Choose your tank coating and tank lining carefully to save time and money
When it comes to protection, tanks present a series of difficulties. Not only does their exterior need protection from the environment, but their interior needs to be protected too – both from and for the cargo or substance being stored. These substances can be anything from petrochemical to water to beer, and the coating needs to combat the specific adverse conditions that accompany the substance while not contaminating it. To achieve this, tank lining and tank coating are formulated to be chemically resistant, hygienic, resistant to high temperatures, and capable of application over previously damaged substrates.
Starting off with the right coating will save you expensive problems down the line, and re-coating a tank is only 10% of the cost of replacing a tank. Whether you need tank coating for a new project, or need to recoat one that is no longer functioning optimally, there is a coating to match your need. In this article we will outline the many benefits of industrial tank coatings, tank linings and how to choose the right one for your project.
The right tank coating is 5 questions away
A tank lining needs to match both the substrate and the storage. They form a barrier, protecting the substrate from corrosion, chemicals, and heat, and protecting the contents from contamination. Tank lining and tank liners refer to two different products – tank lining adheres to the surface of the tank and forms a seamless barrier, where tank liners are installed as a freestanding barrier. Some tank liners are dropped in then bonded and sealed to the tank. In order to determine the suitable coating for your project, you need to be able to answer these 5 questions:
- What is the maximum possible downtime during application? Different tank coatings have different application and curing times.
- What are the local regulations regarding tank linings? The tank lining needs to comply with local standards.
- What is the tank storing? Chemicals, foodstuffs, water, each store has different needs.
- For how long will it be stored? Coatings can be formulated and applied to provide longer protection against constant exposure.
- What temperatures will the tank lining be exposed to? Both the environment and the cargo need to be taken into account.
Special tank lining for cargo and water tanks
The purpose of your tank will be the shaping influence on which coating you choose. This is particularly important for:
- Water tank coatings:
Tanks for both potable water and other kinds of water (waste, raw, etc.) make up most tank usage in the US. For potable water it is of vital importance that the tank and the coating do not contaminate the water, just as it is important that the coating protects the tanks from corrosion. In the US there are regulations for the coatings used for potable water. For wastewater tanks, the coating needs to be highly chemical resistant, as well as preventing the pollution from within the tank seeping into the environment, especially where the tanks are underground.
- Cargo tank linings:
For cargo tanks, the storage changes with each new job. Because of this, the lining chosen needs to protect your tank against harmful or corrosive cargoes while also reducing maintenance and ensuring a long service life. A tank lining system should reduce turnaround times between cargoes, allowing a quick switch and eliminating contamination between cargoes. It is important for cargo tanks to have chemical resistance, so common cargoes such as petroleum or oil do not damage it.
Choose from the 3 most common tank lining types
In the US the most tanks are used either for storing or transporting a spectrum of substances. Mild steel tanks are the most common but also other materials such as fiberglass and concrete are becoming more and more popular. So, let’s look at the different tanks and the tank linings they require. The incorrect choice of tank lining may lead to softening, contamination or even failure of the coating.
1. Polyurethane tank lining
Uses: Water tank linings, steel tank linings, concrete tank linings, chemical tank linings
Description: Polyurethanes are, like epoxies, a very versatile coating, and they have the benefit of being able to be modulated so they are more or less flexible/brittle. They can also be solvent-free, and have faster return-to-service times than epoxy.
Cons: Not vapor permeable (possible blistering), and very moisture sensitive when applied.
2. Epoxy tank lining
Uses: Water tank linings (potable and other), steel tank linings, concrete tank linings, chemical tank linings, high temperature tank linings, cargo tank linings where protection against chemicals, oils, waste water, high temperature crude oil is needed.
Description: Epoxy is a versatile coating type with many applications. It can be solvent-free to reduce VOC emissions, and protects against corrosion in aggressive and high temperature environments.
Cons: Not a very flexible coating, slow curing, impermeable so water vapor may cause blistering.
3. Polyurea tank lining
Uses: Water tank linings (not potable, but excellent for wastewater), steel tank linings, concrete tank linings, chemical tank linings
Description: Polyurea is a hot spray applied coating which dries in seconds to minutes, with the shortest cure time of all the options. It has great strength and flexibility, and the highest tensile strength of the coatings – allowing for stretching with a substrate under temperature extremes. Polyurea is solvent free (no VOC), moisture insensitive (unlike the other two), has a long service life, and is also abrasion resistant.
Cons: Not vapor permeable.
Tank coating and lining products & services in the US
For quality assurance and expert application, we advise you to have your tank lining applied by trained, experienced professionals. The risk of a coating failure due to poor or wrong application is too costly a gamble. We have compiled a sample of the products used by American applicators, to give an idea of the products available.
|Tank lining product||Description||Tank substrate and storage|
|International Interline 704 (AkzoNobel)||Epoxy coating with a 15 hour drying time (depending on temperature)||Steel storage tanks containing crude oil, gasolines, MTBE, caustic solutions, and solvents|
|International Enviroline 124 (AkzoNobel)||100% solids Epoxy Novolac coating with a 3 hour drying time at 77°F||Steel tanks which need high chemical resistance, above and below ground|
|Hempel Hempadur 15500||Epoxy Novolac coating with a 6 hour drying time at 68°F||Internal lining for a vessel’s cargo tanks, storage tanks and rail cars|
|Hempel Hempadur 85671||Epoxy Novolac coating with a 6 hour drying time at 68°F||Interior lining in steel and concrete tanks for hot water, brine, crude oil, vegetable oils, molten sulfur and other chemicals|
If you would like more information about tank lining, or have a tank coating project that requires coating expertise, get in touch! Our experts are here to help, and ready to connect you with one of our coating partners to best complete your project. Just click the “Request a quote” button at the bottom of this article and take advantage of our 100% free quote service.
Primary and secondary containment tank coating regulations
The tank in which a substance is stored is known as the primary tank (primary containment). However, to protect against environmental pollution due to a failure or leakage of the primary tank, this must be encapsulated in what is known as secondary containment. A bund is a secondary containment system. These must also be coated suitably to protect against the contents of the tank.
In the US, tank coatings and linings are subject to rigorous testing and inspection to ensure they continue to function as outlined by their specification. Not only does a coating failure cost thousands of dollars in downtime, lost revenue, and repair or replacement, but it can mean a violation of regulations. Environmental regulations are strict and tank storage facilities have a responsibility to guard against any tank leakage and ground or waterway contamination.