Corrosion in Diesel Fuel Storage Tanks - Recommendations for Tank Owners

One of our most popular webinars from the past dealt with such an important issue - Diesel Fuel Storage Tank Corrosion - that we thought it was important to share it with our blog readers. Over the course of four articles, we will be sharing the content of that webinar here on the blog.

You can read the first part of this series, Corrosion in Diesel Fuel Storage Tanks- The History of Corrosion, here. You can read the second part of the series, Corrosion in Diesel Fuel Storage Tanks- The EPA’s Methodology, here. You can read the third part of the series, Corrosion in Diesel Fuel Storage Tanks - The Results, here.

Recommendation #1: Visual inspections of filter and inside of UST systems

Understanding the Hidden Risks

Even if your UST system seems fine, hidden dangers could be lurking. The EPA has found that 75% of tanks showed no visible signs of corrosion, yet over 80% had moderate to severe corrosion. This discrepancy highlights a critical gap in tank maintenance awareness.

Regular Visual Inspections: Your First Line of Defense

Whether your tanks are fiberglass or steel, regular visual inspections are non-negotiable. Think of it like monitoring your blood pressure: you might feel fine, but unseen issues could lead to major problems.

What to Look For:

1. Inspecting Filters: Look for sludge or particle accumulation. If you find debris resembling coffee grounds, it's a telltale sign of corrosive damage.

2. Checking Tank Interiors: Don't wait for evident symptoms. Early stages of severe corrosion can go unnoticed but have detrimental effects on your UST system's integrity.

Frequency of Inspections:

If anything, one of the critical takeaways here is that you should establish a routine inspection schedule. Regular checks, even in the absence of symptoms, are essential to prevent unforeseen issues and ensure the longevity of your UST system.

#2: Monitor and remove any water present in the UST

Why Regular Water Removal is Crucial

The EPA stresses the importance of regularly checking for and removing water from USTs to prevent corrosion. Surprisingly, many tank owners and operators neglect this crucial maintenance step. This oversight is especially common in tanks not used frequently or those outside stringent regulatory oversight, like emergency fuel storage tanks.

The Risks of Neglect:

Tanks that sit unchecked for years, such as some diesel fuel storage tanks, are highly susceptible to corrosion-related problems. This can lead to significant safety risks and costly repairs.

Best Practices for Water Monitoring:

1. Utilize Water Monitors: While many systems have water monitors, they should not be your only line of defense. These devices can fail or give inaccurate readings.

2. Human Inspection is Key: Regular physical inspections by trained personnel are irreplaceable. They not only confirm the readings from electronic monitors but also provide a more comprehensive understanding of the tank's condition.

3. Act Proactively: Regularly scheduled checks are essential, even for tanks that are rarely used. Don't wait for visible signs of corrosion or system failure - by then, it might be too late.

Implementing a Routine Schedule:

• Establish a regular schedule for water level checks, regardless of the tank's usage frequency.
• Document each inspection, noting any changes or potential concerns.
• Ensure that staff are trained in both using monitoring equipment and performing manual inspections.

Addressing Found Issues Promptly:

If water is detected during an inspection, immediate steps should be taken to remove it. This not only prevents corrosion but also helps maintain the overall health and efficiency of the fuel system.

Remember, consistent and thorough monitoring for water in your UST system is not just a best practice — it's a necessity for the longevity and safety of your storage tanks. Proactive measures today can save significant costs and prevent hazardous situations in the future.

Recommendation #3: Fuel should be filtered for water/particulate before it is delivered into the UST

To safeguard against tank corrosion, the EPA strongly advises that tank operators filter fuel for water and particulates, either before delivery into the UST or shortly after when recirculating the stored fuel.

Why Fuel Filtering is Paramount

• Direct Link to Tank Health: The EPA's study showed a strong correlation between water and particulate content in fuel and the condition of tanks. Filtering out these elements is key to preventing corrosion.
• Unpredictable Fuel Quality: Even if you maintain high standards for your fuel, the quality of fuel deliveries can vary. Filtering upon receipt ensures consistency and safety.
• Preventing Accelerated Damage: By removing water and particulates, you're proactively eliminating factors that contribute to fuel instability and tank corrosion.

Implementing Effective Fuel Filtering:

1. Choose the Right Time: Determine whether to filter before the fuel enters your UST or after it's stored. Each approach has its advantages, and your choice may depend on your specific setup and fuel turnover rate.
2. Use Quality Filters: Invest in high-grade filters designed for water and particulate removal. Regular maintenance and timely replacement of these filters are crucial.
3. Regular Monitoring: Even with robust filtering, consistently monitor fuel quality to catch any issues early.

Filtering fuel, as emphasized by the EPA, is not just a recommendation but a necessity for the longevity and safety of your UST. Implementing this practice can significantly reduce the risk of costly repairs and environmental hazards in the future.

Recommendation #4: Partner with UST-servicing companies to further evaluate corrosion problems

Owners should contact UST servicing companies to further evaluate extent of corrosion in their system, if they find corrosion or if they suspect it’s there. They should not hesitate to partner with service companies.

The EPA recommends this because they know that few tank owners/operators have the technical knowledge or resources to fix their own tanks or to more fully evaluate the extent of corrosion problems and damage in their tanks if preliminary signs manifest themselves.

UST-service companies are experts in their field, and solving corrosion issues in tanks should be more in their wheelhouse than a tank operator.

What the EPA doesn’t want to have happen is for tank owners to suspect they have a corrosion problem in their tank, but put off doing something about it because they don’t feel they have the resources or knowledge to solve it. Remember, the EPA undertook this because they recognized that corrosion damage and worst-case scenarios for fuel leaks into the environment had serious potential consequences for both environmental health and human health. They do not want tank owners to put off fixing a problem.

Recommendation #5: Repair or replace equipment if corrosion is found

Action item #5 from the EPA piggybacks onto what we were just talking about. If corrosion damage or its symptoms are found, the affected equipment should be repaired or replaced. And again, remember that a big reason why the EPA looked more closely at this issue was the potential for damaging releases into the environment.

The leak detection equipment in a UST was what the EPA was most concerned about. So, if that, or any other part of the UST, is found to be damaged by corrosion, they have to be repaired or replaced.

Recommendation #6: Use of biocides and liquid corrosion inhibitor additives

So far, the EPA’s recommendations have covered monitoring tank and fuel condition (both stored and incoming), housekeeping measures for contaminants, and the need for not putting off essential repairs.

The sixth and final recommendation addresses simple preventive measures that may be easily done by tank owners and operators themselves. These are the use of both biocides (to kill existing colonies and prevent future MIC) and liquid corrosion inhibitor additives – what the EPA terms “filming amines”.

Why did the EPA specifically call these two treatments out? Because they directly address the problems that tank corrosion is associated with.

EPA Recommendation - Use of Biocides

Given the link between storage tank corrosion and microbial activity, it stands to reason that the EPA would recommend tank operators incorporate something into their housekeeping that most directly controls microbial growth.

Biocides are the only chemical treatment that kills active microbes. So, using them brings both a remedial and a preventive benefit.

So, if a tank has microbially induced corrosion, it also has an existing microbial presence. Treating it with a biocide is the first essential step to killing the microbes, which is the only way to stop MIC from progressing. That’s the remedial benefit.

The preventive benefit comes from interval treatment of fuel storage tanks with low levels of biocide – typically around a 1:10000 treat ratio. This is proven to be the best way to prevent microbial presence from getting established in storage tanks.

This concept – the essential use of biocides as the most effective weapon against the biggest causal contributor to storage tank corrosion – this is a departure from the traditional rule of thumb the industry had held for years. If you kept the water under control, you wouldn’t have microbe problems.

But as they started seeing around 2007, even though they were doing the same things they always did, they were now having corrosion problems they didn’t have before. This was most likely due to the new ULSD fuels and their lack of resistance to microbes (because of low sulfur presence).

Now, it’s clear that water control isn’t enough. Extra measures must be taken. And that means using biocides, as the EPA recommends.

There’s a lot that may be said about selecting which biocide to use, probably a topic that’s worth a whole another webinar in and of itself. Suffice it to say that not all biocides are the same. They use different chemistries (isothiazolone, boranate, thiocyanate, dibam/nibam), and some work better than others in certain situations.

At the risk of over-generalizing, the best biocides will score well in these main areas:

• Kill speed – they should be able to work fast.
• Kill length – the most important one. This is the amount of time the biocide will maintain a 100% kill rate in the fuel. 4 weeks is going to be about the best you’re going to get. That doesn’t mean microbes all come back after 4 weeks + 1 day. However some popular biocides only last 1-2 weeks, and that’s a significant difference.
• Integrity in fuel and water – the best biocides will start in the fuel phase and will migrate or partition into the water phase. This is essential because the process of moving across the interface will kill microbes in that important area. Some biocide chemistries see their biocidal molecules undergo reactions in water, breaking apart into 2 or more different molecules.
• Impervious to pH – some biocide chemistries become less effective in acidic environments. This is a problem because fuels that are more acidic will be more likely to have serious microbial problems. They became acidic because of the low MW acids produced by the microbes.

So, it’s important to make a good biocide choice. If you’re going to take the time and the money to follow the EPA’s recommendation in this manner, you want to make sure you select the right one for you.

Some of the popular biocide trade names, you might have heard of – Bellicide, Biobor, and Kathon. There are differences between them. If you’re not sure, talk to us about it.

EPA Recommendation – Liquid Corrosion Inhibitors

Their other recommendation is the regular use of protective chemical agents that protect tank surfaces from damage.

Liquid corrosion inhibitors are added to the fuel in the tank, typically at very low treat rates between 1:10000 and 1:20000. They use a “filming amine” chemistry to lay down a protective film onto whatever surfaces the treated fuel comes in contact with. This film protects the surface from corrosion as long as the fuel is in contact.

Better liquid corrosion inhibitors also provide other benefits in addition, to increasing their value. They can also function as sludge dispersants and biomass dispersants. So in addition to protecting surfaces from corrosion, they also solubilize tank sludge and dissolve it into the fuel, which cleans the system over time. They can also improve the effectiveness of biocides when used alongside them because they break up and disperse biomass formations in the tank that otherwise would shield microbes from biocide presence.

Bell Performance has one such formulation – Tank Treatment SDF, that provides all of these benefits – protecting surfaces from corrosion and dispersing sludge and biomass.

One final note - there is a biocide chemistry, commonly known as MBO, that combines being a biocide and a corrosion inhibitor. ClearKill is one trade name for it, while if you were in Europe, you could find it sold under the trade name Grotamar. It is a worthwhile biocide to consider if you're aiming to follow the EPA's best practice recommendations here.

Proper Application Is Key for Best Results

To wrap things up, we would be remiss in not mentioning that these essential chemical recommendations – use of biocides and corrosion inhibitors – won’t work optimally if they are not applied properly. Their effectiveness hinges on correct application. It’s not as simple as just adding these chemicals to your fuel tank; they need to be properly distributed to be effective. Let's break this down:

1. Biocides & Contact: For biocides to work, they must come into direct contact with the microbes. Incomplete distribution can lead to ineffective treatment.
2. Corrosion Inhibitors: These need to reach all parts of the tank to provide comprehensive protection.

Application Methods

• Direct Injection: Ideal but may require specialized equipment.
• Addition with Fuel Circulation: More accessible for most operators, this method ensures better distribution of the chemicals.

Overcoming Application Challenges

Many entities hesitate to incorporate these practices due to perceived complexity, lack of time, or resources. However, neglecting these steps can compromise your fuel integrity.

The Role of Service Partners

Consider partnering with a specialized service provider who can:

• Handle comprehensive fuel maintenance, including chemical treatment.
• Perform tank cleaning and fuel filtration.
• Provide diagnostic testing to demonstrate the effectiveness of treatments.

Choosing the Right Partner

A suitable partner goes beyond basic tank servicing or fuel polishing. Look for providers offering a holistic approach, encompassing both mechanical cleaning and chemical treatment, as recommended by the EPA.

Conclusion

Proper chemical treatment is not a luxury but a necessity for maintaining fuel integrity. By understanding the importance of correct application and considering the support of specialized service partners, you can ensure your fuel storage system remains in optimal condition.

Bell Fuel & Tank Services

A good service partner should, essentially, be able to provide a turn-key service – handling all of these important elements – chemical treatment, mechanical fuel processing and tank cleaning, and diagnostic testing. And if you or another company doesn’t need all of these, they should be able to break out only what you need.

And that’s essentially the kind of service we offer with the Bell FTS program. Lots of people with stored fuel know the importance of these best practice recommendations. But it’s easier and more cost-effective for them to let a comprehensive service partner handle it for them. That’s what the Bell Fuel & Tank Services arm does. We cover all the bases, whatever is needed, and typically it’s more cost-effective for Bell FTS to handle it than it is for them to do it themselves.

What Did We Learn Today?

Normally we like to do a brief review of what we’ve covered in webinars like this. We will also make this available as a link with audio in case you missed anything that you want to refresh your memory on.

The important points:

• Due to an increased incidence of problematic corrosion, the EPA tank corrosion study – the largest to date on the topic with over 40 tanks comprehensively studied.
• More than 80% of the tank showed significant signs of corrosion damage. And this was true despite most of those tanks still receiving the same maintenance as they did before. So, it wasn’t like they were just being left there.
• Most of the owners of these tanks didn’t know they had problems or hadn’t seen any signs yet.
• Didn’t matter if it was metal or fiberglass tanks.
• EPA recommends controlling water in tanks, filtering the fuel for water and particulate, using biocide and anti-corrosion chemical treatments, and partnering with service companies to make sure tank damage is properly repaired. And it can also be helpful to partner with a service company like Bell FTS to ensure the fuel is properly treated, to take that out of your hands so you can concentrate on doing business better.

Missed Part of the Story? Catch Up Here

Click here to read the first part of the webinar transcript: Corrosion in Diesel Fuel Storage Tanks- The History of Corrosion

Click here to read the second part of the webinar transcript: Corrosion in Diesel Fuel Storage Tanks- The EPA’s Methodology

Click here to read the third part of the webinar transcript: Corrosion in Diesel Fuel Storage Tanks - The Results