A Guide to Oil Storage Tanks

Everything you need to look after your oil tanks

Oil tank owners have a legal duty to ensure fuels and oils are stored safely and securely. Without regular maintenance and the correct storage conditions, your fuel tank can easily become a liability rather than an asset.

This guide is helpful for anyone who has recently had a fuel tank installed or simply needs to update or refresh their knowledge, showing you the risk factors that you need to look out for and what you can do about them.

Oil tank regulations

There are different regulations that apply to fuel tanks, depending on the fuel stored, where they are located and how much you’re storing. To help untangle the red tape and ensure you’re operating within the law, we’ve put together a dedicated guide which includes everything there is to know for both commercial and domestic use.

The benefits of an onsite oil tank

An onsite storage tank is ideal for businesses who use large amounts of fuel or when oil barrels (drums) are too small or inconvenient. An onsite tank can save you time by not having to make frequent fuel orders, as well as reduced regular delivery costs and improved efficiency within your operations.

Having an onsite tank also allows you to buy fuel in bulk which helps to reduce the price you pay per litre. Companies can also benefit from fuel management systems such as oil tank telemetry monitoring, allowing you to control and monitor fuel consumption to further help reduce costs.

Common oil tank issues

External temperature fluctuations

Unfortunately, it’s quite common for water to get inside a fuel tank, particularly during the spring and summer due to heat gain and evaporation. When the external temperature increases, condensation can form internally and cause the tank to “breathe”. This accelerates contamination by causing water and bacteria to accumulate. 

In 2018, the UK experienced an extremely cold winter which was followed by a particularly warm and dry summer. This led to a 23% rise in callouts to instances of corrosion and reports of fuel contamination.

FAME content in fuels

Fuel tanks also face a number of issues due to the nature of the products stored. The introduction of ultra low sulphur diesel (ULSD) paired with the increase in bio (FAME) content and modern refining techniques has led to a widespread increase in contamination issues. These microbes sink to the bottom of the tank and build up with rust and dirt, resulting in sludge forming on the base of your tank.

Over time this can lead to hidden flaws, cracks and corrosion developing in the structure of your storage vessel. Even minor damage on any storage tank can hugely increase the risk of a tank failure. If left unmonitored, it can lead to an accidental oil spill which can have a significant negative impact on the environment and your bottom line.

While many different types of corrosion can occur, the majority are not visible by exterior examination and further internal testing, such as Non-Destructive Testing, is required.

Tank servicing and maintenance

According to the UK Spill Organisation, an oil spill costs a typical business up to £30,000 in fines, clean-up charges and production losses.

Tank owners have a legal duty to ensure that the fuel stored is safe and secure without posing a risk to the environment. Spills and leaks are extremely expensive to clean up and can contaminate nearby ground water supplies, building foundations, local wildlife and their habitats.  

The ongoing care of your tank is imperative. If you have any concerns about your oil tank, you must contact your fuel supplier or OFTEC registered engineer as soon as possible.

Do you have any concerns? Call our helpline on 0330 123 1444.

Ongoing oil tank care

You should carry out regular maintenance yourself to help ensure your tank lasts longer and is less likely to need expensive repairs or replacements.

A few simple checks now can save you thousands of pounds in the future. Signs of wear and tear include:

• Corrosion and rust
• Splits, discolouration or cracks in the tank
• Bulging and warping
• Faulty gauges
• Subsidence on the tank base
• Unusual oil smell

Oil tank types

There are two types of oil tanks: steel and plastic. Both have different advantages; some fuel users prefer the non-rusting properties of plastic tanks whilst others are drawn to the strength and robustness of steel tanks.

At Crown Oil, we supply both plastic bunded oil tanks and steel bunded oil tanks in a range of sizes across the UK. To help you decide which oil tank is best for you, we’ve comprised the pros and cons of both types below.

Plastic tanks

Plastic fuel tanks are a popular choice, especially for domestic use, as they are cheaper and don’t rust like steel tanks.

Benefits of plastic tanks

• Constructed from polyethene, making them less prone to corrosion than steel tanks
• A lightweight solution
• Fully compliant with all regulatory requirements
• A variety of off-the-shelf sizes
• Easy to install and manoeuvre
• Plastic is an insulator so there’s a reduced risk of contamination
• Deformed tanks can regain their original shape, provided there are no cracks
• Readily available and fully bunded

Drawbacks of plastic tanks

Once a plastic tank is damaged, you have no choice but to replace it which can be costly and inconvenient. A cracked fuel tank not only puts the environment and wildlife at risk, it also puts your fuel at an increased risk of contamination and spillage.

A damaged tank also increases the risk of water formation inside a fuel tank which encourages diesel bug growth. This can clog filters, injectors and fuel lines, and lead to a sudden and expensive halt to your operations.

Plastic tanks can crack due to several reasons:

• Cold weather – splits and cracks are common in low temperatures and from bouts of snow, putting the environment and wildlife at risk
• Temperature fluctuations – plastic tanks undergo huge stress when located outside from the weather and temperature fluctuations
• UV exposure – sunlight can cause whitening and discolouration which can lead to twisting, bowing and expanding of the plastic
• Stress – Plastic tanks can crack and shatter under heavy strain, from being installed on an uneven base or through the weight of snow or organic debris 
• Accidental damage – In high traffic areas, such as business yards, plastic tanks are at greater risk of irreparable damage that a steel tank would be able to withstand

Steel tanks

Steel tanks are usually used to store bulk amounts of fuel due to their desirable characteristics when compared to plastic tanks.

Benefits of steel tanks

• Sturdier and more resilient than plastic so can withstand greater impacts onsite
• Non-porous, meaning they won’t absorb any of their contents
• Fully compliant with all regulations
• Available in standard and bespoke sizes
• Can be repaired and patched, unlike plastic tanks
• Much longer lifespan than plastic tanks

Drawbacks of steel tanks

The properties of a steel tank also mean that they are more prone to corrosion from varying weather conditions such as UV light, heat and condensation. These fluctuations can cause chemical or electrochemical reactions between tanks and the environment and over time, leading to tank corrosion.

If ignored, corrosion not only causes the tank’s contents to degrade in quality but also negatively affect the tank’s integrity. This will eventually penetrate the tank structure, causing problems such as tank bottom perforation. If oil escapes through the tank’s walls, you risk damaging the environment, as well as expensive clean-up costs and voided warranties.

In a 12-month period, our engineers were called out to 482 instances of corrosion.

The vast majority of these cases could be avoided by regular checks, simple tank maintenance and keeping fuel levels optimal to reduce the risk of moisture in tanks.

So what can be done to protect tanks and fuel?

A proactive approach must be maintained to uphold fuel quality. While some degradation is inevitable, a wide range of techniques and materials have been developed to help prevent it.

Looking after your storage tank is essential to preserve efficiency, reduce pollution and prolong longevity.

Use a double skinned tank

A high-performing liner (either a single or double skin) provides leak detection and acts as a safety net, offering an excellent return on investment.

A double skin offers twice as much protection and ensures the original tank is contained within a vacuum to combat tank issues as there is no moisture or air held between the two skins. It also provides an extra layer of protection against accidental damage and impacts that would compromise a single-skinned tank. The thicker the skin, the better the protection.

Ensure your tank is bunded

A bund, also known as secondary containment, is constructed from concrete or brick and is legally required to contain and prevent spills that can occur from tank penetration. The extra outer protective layer will protect the tank and must be able to hold 110% of the contents under UK law.

If there is a leak or breach of the inner tank, such as overfilling or water build-up in the tank, the outer bund can fully contain it safely. It cannot escape to contaminate the surrounding environment, such as your site, nearby water courses or the environment.

Outside bunds are exposed to the natural elements so are likely to become filled within rainwater, organic debris and dirt which builds up and decreases the containment capacity over time. This increases the likelihood of oil escaping and surpassing the bund wall if a tank fails, so it’s vital that robust measures are implemented to extract rainwater from exposed bunds. For example, a valve should be kept closed at all times but can be opened to drain uncontaminated rainwater as necessary.

Keep tanks topped up

As well as structural preventative measures, keeping fuel tanks full, particularly during the hotter months, will leave less space for air. This means less humidity and condensation, and therefore a reduced risk of microbial growth.

Invest in regular tank inspections

Regular tank inspections are key to mitigating a whole host of problems which are common with both new and old tanks, as well as reducing the risk of oil leaking into the environment.

Our tank inspection services can help you avoid huge fines by leveraging our environmental expertise. We have the technical knowledge, experience and facilities to thoroughly test your fuel storage infrastructure for common and hidden faults, and provide remedial services if required. If these issues have already affected your fuel supply, we can also restore your fuel to an optimal level of cleanliness if required, securing the future of your business and its fuel supply.

The importance of internal tank investigations

Tank issues usually progress from the inside out, so the extent of the problem is often not known until external issues manifest. By that point, it can often be too late to rectify.  

As a rule of thumb, diesel should be stored for no longer than 12 months without being checked by a professional company. This will ensure your fuel meets usable specifications so it can be confidently relied on by your business.

Good practice when storing fuels onsite dictates that tanks and pipework should be regularly tested to ensure their integrity. By undertaking a proactive approach rather than reactive, you will help prevent business downtime and avoid having to fork out hefty clean-up costs from environmental damage. 

Oil tank disposal

As your tank starts to age, it’s important to keep a close eye on it. Once it’s out of warranty, it’s advised to replace sooner rather than later to avoid expensive issues from developing.

At Crown Oil, we can uplift the fuel, decommission and remove your tank safely and quickly, and supply a new tank at competitive rates.

If you’re concerned about your storage tank or are looking for some specialist advice, give us a call on 0330 123 1444 today.