The problem

Did you know that your oil tank can suffer from corrosion when keeping tanks partially full?

We recently visited an underground storage tank at a data centre which was suffering from an extensive amount of corrosion because their tanks were only partially filled.

This corrosion was able to manifest and spread as the tank’s vents exposed the interior to the external atmosphere over a long period of time. As a critical component of a backup power system, diesel stored for emergency use must be maintained in optimal condition to ensure start-up and runtime of backup generators.

Steel tanks don’t like water – and a tank that contains more air than fuel is likely to accumulate condensation (water) on its inner walls as external temperatures fluctuate, particularly during the British spring months.

The images below show where the tank has been filled to and the area above which has succumbed to corrosion.

Oil Storage Tank Corrosion

What is the problem with condensation in oil tanks?

Hydrocarbon-based fuels, like red diesel, white diesel and heating oil are at a high risk of degradation through absorbing water from moisture in the atmosphere. This is a huge problem for stored fuel, particularly in long-term storage at data centres, as it causes free water to collect on the bottom of your tank and smaller particles to remain suspended within the fuel.

Water reacts with naturally occurring bacteria and causes sludge matter to accumulate and clog filters.

All of this dramatically reduces fuel’s shelf life and necessitates the need for regular fuel testing.

Condensation creates two issues for your oil tank: it creates the perfect conditions for microbes to grow in your fuel, which can cause sludge to accumulate in your tank and clog filters – and secondly, as water is heavier than oil, it will sink to the bottom of your tank, speeding up corrosion and eventually leading to tank failure.

Should the tank have been left like this for any longer, it would likely have sustained further corrosion, leaving the tank irreparable and unfit for use.

Without regular tank inspections and fuel deliveries, contaminants can decrease a tank’s integrity over time and lead to an increased likelihood of spills.

The solution: use a FAME-free stable fuel with a shelf life of up to 10 years

An increasing number of our data centre customers are realising the benefits of Hydrotreated Vegetable Oil (HVO), a 100% renewable fuel that works almost identically to conventional diesel. Derived from solely waste materials, HVO can be used as a direct, drop-in alternative but doesn’t face the stability issues that fossil fuels experience.

This is a key benefit for data centre operators – the ability to leave HVO in a tank for up to 10 years with no appreciable degradation, provided good tank husbandry and storage conditions.

Another critical benefit of HVO is that it reduces up to 90% of net CO2 emissions and significantly reduces notifiable air pollutants such as nitrogen oxide and particulate matter.

Concerned it might be too late?

Take advantage of our free site survey which is offered to all our large commercial customers and data centre sites. This service includes comprehensive fuel testing in our onsite laboratory at Crown HQ to determine the condition of your fuel system. We are then able to advise on the best course of action in a detailed report.

If the fuel is found to be contaminated and in poor health, we offer a buy back and rebate option for degraded stored fuel, providing the volume meets our minimum requirement for this service.

After the fuel has been uplifted, the tank will need to be cleaned by a full man entry tank clean. All our engineers have the required qualifications to ensure any challenges are addressed, such as working in confined spaces and cleaning hard-to-reach areas.

From the invasive clean, if the tank itself is showing signs of deterioration due to the low fuel levels (as shown in the images) it’s advised that an engineer fully examines the tank to ensure its integrity and safety by completing an NDT inspection. This is a must if you have concerns about the tank before you refill with your new stock.

Unrivalled service

The Crown Oil Group is proud to be able to offer all these services in-house with no external experts or use of third-party contractors who can often be difficult to manage and maintain. Our comprehensive service portfolio ensures your site is not only managed by the best in the business but also ensures your projects are completed on time and within budget by a company you can trust.

Save your business from lost revenue and a damaged reputation. Call 0330 123 3399 to book your tank inspection today.