Diesel corrosion

[PatSmyth]

Thanks Zane, just downloaded it from https://crcao.org/published-reports-full/.

I focus on the effect of biodiesel, and Fig 62 from this report gives an excellent depiction of how biodiesel and water interact. I can't post Fig 62, but the description says: Figure 62. Surfactants – a) schematic of surfactant molecule showing polar head and nonpolar tail; b) schematic of invert-emulsion micelle showing polar heads encapsulating water droplet and nonpolar tails extending into the medium (i.e., fuel); c) schematic of invert emulsion micelles dispersed in fuel; d) photo of 10 mL each fuel and water – left: before shaking; right: 24h after shaking (note stability of invert emulsion).

I have seen this stable invert emulsion on every tank I sampled that had B4 for 10+ years. No free standing water, rather a layer of haze, with water content running from 1200 to 28000 ppm. This layer is only a few inches thich. An ideal growth volume for microbes. In addition, since gensets draw fuel from the bottom, excess concentrations of water and biodiesel will increase emissions, lower power, and could damage the injectors

[ZMiller]

The latest report still reacting and reporting on symptoms while ignoring the problem. CRC should be studying tanks in further studies that don't have issues and looking for the differences.

[PatSmyth]

I agree. From the report "The results from this 12-week study confirmed that the presence of free-water was essential to corrosion".

There are two existing solutions that can address water in stored diesel. First off is nitrogen blanketing, which can prevent the absorption of water vapor into the fuel from the atmosphere. In addition, heated nitrogen bubbling through the fuel column can remove water from the fuel.

Secondly SAE J1488_201010 filtration was specifically designed to remove water in biodiesel blends. There are companies that can remove 96% + of the water in a single pass, leaving fuel well under 200 ppm water.

I see nitrogen blanketing on terminal storage tanks, and SAE J1488 filtration when fuel delivery trucks are loaded. This ensures dry fuel is delivered to the customers.

For customer tanks that store diesel for long periods, such as for emergency backup generators, I see both a blanketing and SAE J1488 filtration system.

[ZMiller]

You know there are probably people out there at the XYX knowing what they know about the history of ocean travel and women, That would still consider taking if offered, two Deluxe or First Class honeymoon cruise tickets on the Titanic's madden voyage.

Ships and now diesel and premium gasoline fuel storage tanks.

In both problemed scenarios the issue seems to have been and or is to much WATER.

Hint; Don't use a cheater on the wrench used to unscrew a product line leak detector........................................

[tankgenie]

Thanks for all the latest updates Pat and Zane.

[ZMiller]

The industry seems to be encouraging study and reports addressing root causes hoping that they will be inconclusive. This only means that no body wants to know for fear that somebody will end up taking the blame. For those studying the issues it may be that they have never owned or actually operated a commercial or retail fueling facility where fuel is stored in glass or steel tanks. Two cents worth of study probably would conclude that fuel stability and quality should be of utmost concern. You can not stop corrosion but you can slow the progression of it down. Protect the quality of fuel being stored and the containment degradation and down stream issues likely go away.

Water (wet fuel) in the fuel column being the most common factor causing issues? Then stabilize and protect the fuel.

[ZMiller]

Re: Corrosion Issue Symptoms or Solutions
Post by ZMiller » August 24th, 2021, 9:06 am

A major problem lies in the fact that the microbes living in diesel fuel excrete acids that damage the tank, fuel system components and fuel quality over time. Low fuel pH is a sign of this problem. Remember that low pH means high acid. The normal pH for diesel fuel is between 5.5 and 8.0, so a reading of below 5.5 is an indicator there could be a problem. The industry recognizes that the lower the pH, the higher the potential for serious corrosive damage to metal components in the system. Some systems with serious corrosion problems have had fuel pH measured as low as 2.5.

There is no known product on the market to raise the PH levels in diesel fuel. If you have low fuel pH, you have to address the source of the problem, which is usually microbes supported by water resident in tank and or fuel column. Once these are under control, the fuel pH will eventually rise and stabilize through normal consumption and dilution that occurs when more fuel is added to the tank. In cases where fuel pH is extremely low, the other option is to dispose of the fuel. No viable chemical treatment will fix a low fuel pH problem.

[ZMiller]

There are simple, inexpensive and almost instant pass or fail 10ml field test kits that will identify low pH in stored diesel fuel tanks.

I might suggest they be utilized to regularly monitor fuel conditions in critical use fuel tanks.

[ZMiller]

It's now my understanding that corrosion in tanks and containment sumps is no longer an issue?

[ZMiller]

FUELS INSTITUTE DIESEL FUEL SAMPLING STUDY 2021
An interesting read for those interested. Link PEI in Tulsa Letter.

The Fuels Institute’s Diesel Fuel Quality Council commissioned a fuel quality study to better understand the condition of diesel fuel sold and consumed in the U.S., and specifically, to evaluate diesel fuel for specific properties that may affect engine operations and/or contribute to tank corrosion and product contamination. The Council collected 190 nozzle samples and 134 tank samples from around the country and conducted 11 tests on every nozzle sample, six tests on every middle tank sample and five tests on every bottom tank sample. The report summarizes the findings of these tests in comparison to selected comparable benchmarks and evaluates the existence of any correlation between variables.

https://www.fuelsinstitute.org/Research ... ling-Study