Page 5 of 16

Re: Diesel corrosion

Posted: Fri Jun 17, 2016 1:03 pm
by bugbuster
ZM: No argument, the bugs are pesky. Moreover, too often, folks treat with a biocide - thinking that the treatment will work magic. First: if the UST is heavily contaminated and has a substantial slime layer (I've seen accumulations >0.5in!), biocide treatment without tank cleaning as part of the same corrective maintenance action is a waste of time and money. It's like taking one dose of an antibiotic that you are supposed to take daily for weeks: you'll kill some of the bugs, but the rest of the population will be left untouched. Second: although biocide labels list acceptable does ranges, unless you treat at the maximum dose, again you are wasting time and money. Third: biocides need to be soluble in both fuel & water, so that they can disperse throughout the fuel and contact all fuel-contacted surfaces. True, it's impossible to treat slime growth on UST ceilings and other headspace surfaces this way, but if your contamination is that heavy, my first point applies. There's now way to get at these surfaces without having a cleaning crew actually enter the tank. I agree that nitrogen blanketing can help reduce slime accumulation in UST headspace. Fourth: Biocides need time to work. 24 to 48h soak times are optimal, but unrealistic. The best we can normally do is add biocide just before a product delivery, so that both surface area coverage and soak time are maximized (recognizing that at high volume sites, this might be <8h). In my experience, folks how have adopted effective condition monitoring and data-driven, early treatment programs have reduced bug-related problems and overall maintenance costs dramatically.

Re: Diesel corrosion

Posted: Sat Jun 18, 2016 8:31 am
by ZMiller
Company operated tanks generally are kept full and worked from the top. Independent operators normally can't afford or justify keeping tanks full and typically work off tank bottom with only two or three days of throughput volumes. Tanks being mostly empty is not how tanks are designed to be used. Empty tanks open to atmosphere will accumulate moisture that wets exposed tank wall surfaces. Wet surfaces and empty space microbial produced low PH values encourage corrosion.

Re: Diesel corrosion

Posted: Sun Jun 19, 2016 7:14 pm
by cbauden
I would be interested in seeing the increase maintenance cost per gallon survey for corrosion in steel diesel fueling systems and tanks. Thank you for offering to post.

Re: Diesel corrosion

Posted: Mon Jun 20, 2016 10:51 am
by ZMiller
.0036 cents per gallon.

Re: Diesel corrosion

Posted: Tue Jun 21, 2016 4:03 pm
by tankgenie
ZMiller....I would love to see the math on that. Can you explain more?

Re: Diesel corrosion

Posted: Tue Jun 21, 2016 4:59 pm
by ZMiller
The math is a secret but for you I'll make an exception.

Re: Diesel corrosion

Posted: Wed Jun 22, 2016 8:38 am
by cbauden
ZMiller,

I would be helpful to see how the corrosion cost of $0.0036 was developed. What were the inputs?

Re: Diesel corrosion

Posted: Wed Jun 22, 2016 9:22 am
by ZMiller
PART ONE
First one has to determine what normal maintenance costs are.

What being normal means was a hard part of the survey formula to caculate.

With an example being filter manufacturers recommend changing filters at six month intervals or when product flow becomes restricted. Well please show me a customer that changes filters when they are supposed to.

It is in most jurisdictions the responsibility of the station owner to check calibration of meters.

Store managers and delivery truck drivers are supposed to stick tanks for water and at the very least make sure the tank fill has a cap on it.

Now I could go on and on about how one is supposed to maintain a gas station but we might all soon be no longer needed.

Response to fueling site issues or problems including corrosion is generally reacative and not preventative.

It may be best to say that sites surveyed included those where there either was or wasn't a maintenance plan or program in use. Cost per gallon differentials on well and properly maintained properties increased but were thought insignificant.

Re: Diesel corrosion

Posted: Fri Jun 24, 2016 2:55 pm
by ATLTech
Solid Math!!!!

Re: Diesel corrosion

Posted: Fri Jun 24, 2016 3:19 pm
by cbauden
Z,

When do you expect to post Part 2?