Diesel corrosion

djenkins · Post by **djenkins** » Sat May 24, 2014 12:06 pm

Corrosion:

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We have a c-store in NJ/NY area with 3 x 12,000g F/G diesel USTs. Throughput is 10,000 to 20,000 g/day. We have treated with biocide on a monthly basis; have no significant water; bottom samples show clean fuel. Yet we still have bouts with heavy corrosion in STPs, meters and filters, to the point that nozzles are not closing completely, and/or nozzles dispense fuel without registering on registers.

Sales reps say "try this treatment", at great expense, but we can't seem to get at the bottom of this. Have not done costly lab analysis - yet.

From what I've learned on my own, I firmly believe the vapor spaces in the tanks have become highly acidic, causing the corrosion. All product is pulled from one terminal on the Hudson River.

Any experiences out there similar to this???

Post by **whittingtonm** » Tue Jun 17, 2014 4:14 am

ZMiller? From talking with Zane and reviewing other reports, that vapor space issue seems like a good suspect for a lot of the corrosion we have been seeing. Why else would risers corrode and drop corrosion onto the V-R float, for example?

tleaf · Post by **tleaf** » Tue Jun 17, 2014 5:03 am

If you read that Battelle report, you'll find that the acetic acid formed by bacteria and ethanol in the fuel rises to the top of the fuel surface, and vaporizes into the tank headspace. Acetic acid has a higher vapor pressure and thus goes directly into the vapor. Of course, we cannot fill the tank high enough with biocide treated fuel to deal with this.

I guess what we need is a biocide that vaporizes!! Gas masks anyone?

SuperTechNOT · Post by **SuperTechNOT** » Fri Oct 03, 2014 7:22 am

With the amount of drop tubes every year that takes hours instead of minutes to remove because they are fused to the riser got to be some issue other than water.

Post by **ZMiller** » Sat Jan 31, 2015 10:28 am

Control of diesel corrosion issues in the tanks empty space have been somewhat resolved with installation of inexpensive nitrogen padding systems. Installation of padding systems when combined with a vending option makes the cost a push. Sump corrosion issues though ugly are not much of a component integrity concern.

Unfortunately we are now seeing ULS Gasoline introduction and corrosion system component failure issues in California and along the Gulf Coast. The issues seen mimicking those as with ULS Diesel.

Post by **ZMiller** » Fri Feb 27, 2015 12:36 pm

I say again who's fooling who?

In the refining of petroleum products, such as crude oil, hydrochloric acid is generated which can cause high corrosion rates on the distillation unit metallurgy, including the overhead system. Neutralizing amines are added to the overhead system to neutralize the hydrochloric acid (HCl) and make it less corrosive. However, excess amines can form salts that will also lead to corrosion. Consequently, the refining industry has, for many years, suffered from amine-hydrochloride salt deposition in crude oil distillation towers, overhead and pumparound circuits. The problem occurs when ammonia and/or amines are present in the desalted crude. These amines react with hydrochloric acid and other acids while ascending the crude tower and deposit as corrosive salts in the tower and the top pumparound equipment. The amines can be present from several sources, including but not necessarily limited to, crude oil (e.g. hydrogen sulfide (H2S) scavenger chemicals--amines added to neutralize the corrosive and other deleterious effects of H2S), slop oil (frequently containing gas scrubbing unit amines) and desalter wash water (often composed of overhead sour water containing amine neutralizer). The problem has worsened in recent years in part due to higher crude salt content, which yields higher HCl contents as a byproduct and in turn requires more overhead neutralizer, consequently both salt reactants are present in higher quantities at the process level and down stream. Additionally, market conditions have encouraged many crude towers to be operated at a colder top temperature, which further encourages salt formation in towers. Longer run cycles between turnarounds have caused problem resolution to become a priority.

Additional changes are foreseen which are likely to make the problem even worse. The economic incentive to use discounted crudes has led to a general deterioration of crude quality, and further, more plants are attempting to maximize internal water reuse. A recent effort to design new amine neutralizer options for overhead systems does not offer relief in all cases, because such amines will not help in systems where salts are present from ammonia or tramp amines entering the system with crude oil or slop oil.

Clearly, amine salting in towers has become a bigger downstream problem in recent years, and future trends indicate continuation of the problem.

I would like to know why the Battelle Report conclusion is reading like a press release form a major oil company by suggesting further study while ignoring what seems to be obvious causes and compounding issues?

Post by **ZMiller** » Thu Nov 05, 2015 10:59 am

Seeing this post has been around since 2012.

Have we learned anything?

cbauden · Post by **cbauden** » Thu Jun 16, 2016 1:23 pm

Good question whether anything has been learned since the initial posting of this string in 2012. The refining process of ULS diesel has caused increased complaints of corrosion, fuel quality, and clogged filters in UST. One cause is from microbial contamination. Even in FRP tanks these pesky bugs can attack the resin of the tank causing delamination of the fibers.

We have also experienced increasing bug problems in gas, especially containing ethanol. Water is one of the big problems here; not just from the ethanol absorbing water but from poor house keeping practices as well. One comment in the string stated there was no significant amount of water in the system. Bugs don't need significant amounts of water.

A microbial audit is the first step in determining whether a bug problem exists and how to combat it. The audit also provides recommendations for reducing the cost impact of uncontrolled microbial growth.

What do you want to do?

Post by **ZMiller** » Fri Jun 17, 2016 8:06 am

Chauden thanks for reviving the topic,

You are correct with the observation that corrosion is now showing up in gasoline tanks. More so at alarming rates. You think we have a problem now? We ain't seen nothing yet just wait a year or two.

The pesky bugs and molds are inherent in ULSD and to a degree in all fuels. There is no way to permently get rid of them. At best you control the environment and the bugs communal activities. Again I say bugs are not Darwinian. They survive using diversity and the ability to quickly adapt to conditions in their environment. Because microbial strains are so numerous and diverse none in tanks can maintain dominant colonitations. Chemically you can treat but what ever bug or mold you kill is just replaced in cycle by another strain, sister, brother or cousin.

There are corrosion control methods that control the environments in storage tanks BUT advising changes to control corrosion in tanks and fueling systems would be admitting there is a problem. Admitting there is a problem then people start looking for who it might be blamed on. In the mean time we watch the worlds infrastructure of storage tanks just rot away.

Let the xxxxx regulating agencies and research institutes continue their finger up the xxx with "we need more study" efforts to define the problem without trying to actually solve the issues. We know what we can't change causing the corrosion for God's sake so why not get started resolving and preventing premature system component and tank failures.

The best advice for tank owners with any brains might be to read the fine print on their tank warranties. Then clean up their maintenance issues and where necessary install simple and better corrosion control equipment.

Post by **ZMiller** » Fri Jun 17, 2016 8:29 am

There is an increased maintenance cost per gallon survey just completed for the corrosion effect in glass and steel diesel fueling systems and tanks. I'll post it if anyone is interested.

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