Monday, January 28, 2013

Diesel Fuel Additive Corrosion Testing

Before any testing project can begin, we try to understand as much as possible. While on some subjects I struggle, some are closer to my heart and background. As an API tank inspector and 30 year chemical engineer, tank corrosion is one of the latter.

It's nice when there is an industry proven and well documented test protocol, but many boat applications lack these; they are just not high volume like automobiles. Often regulators try to apply automotive rules and standards, and like the fuel tank vent filters, they often miss the mark completely. Corrosion testing is one of those, since marine systems are completely how they are used and what they see.

I came across a study by Battelle, funded by the API intended to pin the blame for ULSD corrosion problems in part on ethanol. While I don't think much of our whole ethanol policy, I feel Battelle failed to make a conclusive case; there are simply too many factors, even though they may be right in part. They knew this, careful stating that the hypothesis was possible but not assigning causality. The most important failings were that most of the samples displayed some evidence of treatment with additives (specifics not determined), that other corrosive chemicals were present, and that there was no control case (one tank was asymptomatic, but it contained similar contaminants). Thus, the sample group was not well controlled, the fault of the client and not Battelle. In fact, because the data doesn't fit the hypothesis I believe much of it is honest science, with the conclusions overly extrapolated by the client. The Ethanol trade group responds by accusing the API of bad science and warped publicity, an amusing example of the skillet calling the kettle black.

For example, look at the composition of the bottom water. Note that NY-1 was non-symptomatic, while the other 5 displayed serious corrosion issues.

Chloride. Since this wasn't in the fuel to begin with, I would like to assume this is seawater. The NC-1, NY-1 and NY-2 samples have enough sodium to support this--in fact the the bottom water is 7-25% seawater, and I would think marine tanks could rationally be higher.

Glycolate and formate. Interestingly, these are primary decomposition products on ethylene glycol based antifreeze, and they were only found in the non-symptomatic tank. I wonder if that tank was somehow exposed to antifreeze, which would stop corrosion.

Acetate. Almost certainly from acetobacter, as they have supported with DNA testing. Was the food source ethanol? That is IMHO a stretch, but that doesn't mean organic acids are not common bacterial by-products. These levels are high, like 5-20% vinegar.

Fluoride. Common ingredient in hydrodesulfurization catalysts, though I'm very surprised to see it in these concentrations. It must accumulate in the water phase, suggesting that some of the water in these tanks came with the delivery. Finely dispersed water droplets must have collected the ions. Could be significant contributor to tank bottom corrosion, similar in action to salt water. I found it curious that they never mentioned this data.

pH. Supports organic acid numbers, though there has clearly been some neutralization. Could biodiesel contamination also affect some diesel? Sure, but all we can do is go by what we have measured; low pH. Like many other analytes that are affected by biological activity and pH--nitrate, ammonia, carbonate, calcium which can precipitate--it hints at the current condition but not so directly at a contaminant source.


While there is too much going on to nail down cause and effect, I think it's clear enough we can look at adding seawater and vinegar at dosages similar to those above. In practice, to insure some acceleration, I will increase them somewhat, using 25% seawater and sufficient vinegar to reach a pH of 3.5 (this isn't far from the pH of vinegar, so I will limit acetate to 35,000 ppm, which is a 40% solution of white wine vinegar). I think I can support my basis as more valid than the industry standard tests, which is designed around pipeline transport and uses distilled water and mixing.

In the end, we can prove which corrosion inhibitors will work all of the time, only which work in a specific set of circumstances, and that those circumstances represent a realistic scenario. Practical engineering with a few roots in chemistry.


Jessica Smokes Her Dad at Yet Another Sport....

Thank goodness there are still climbing and skating.

Yesterday we went to Liberty, for the first time in 2 years; last year there was no winter, and even 10 days ago they have only sparse cover. Though Jessica took to skiing like a duck to water, dad was able to stay ahead, relying on a deep base of ice skating skills and considerable effort. This year I got smoked.

  • I've laid off everything for 4 weeks, trying to get a rib to knit. The rib is better, but the legs were mush. It's different from biking too; high intensity rather than endurance.
  • I was being careful. I didn't want to fall, so I was less relaxed. But I did ski blues and blacks all day with zero falls, keeping up with the squirt until near the end, and I feel good about that.
Late afternoon, after having serious thigh cramps--so bad I had to lay down mid-slope and stretch--and preparing to call it a day, I joined her at the top of a double black diamond with a particularly steep start; about 200 feet at 45-35 degrees. Crampons would be required for accent, no way I would hike down it without them. Like looking down an icy staircase. I had already decided I would only watch. We watched a half dozen good skiers start down, sliding and falling, and groping their way down until it leveled out to a more human slope. Then Jessica mumbles some crap about it looking too hard (like she heard dad mutter before many rock and ice climbs--a private inside joke) and easily carves down the escarpment, like it was the bunny slope, with nary a break in form. I went off to cry.

Well, actually, I did take an straight forward black down to the lodge--I'm not that dead--where upon I had a medicinal Stella and waited for nightfall.

Tuesday, January 22, 2013

Practical Sailor--What Would You Like To See Tested?

rev. 3-8-2013

About 50% of the testing starts because a contributor has a problems and decides to expand his research enough to make it worth publishing. I started by investigating phase separation and additives because I was having trouble on my boat, but I went much farther down the rabbit hole than I would have for my own interests alone and learned a lot. We get curious. 20% comes from new stuff we see in a boat show or catalog or someone talks-up. The fuel tank vent filter bit started that way; I though it was a gadget but found value when I looked farther. The remaining 30% comes from suggestions or problems we hear of that seem common enough and where some research might yield an answer for many. The Joker valve bit started that way; I've seen too many valves ruined by propylene glycol and that brought fire to my pen. I tend to focus on chemistry-related topics; I'm a chemical engineer by training and long practice. But I've branched out occasionally if I saw a question I thought I might be uniquely suited to research. Some times a topic is assigned to me and I have to grow interested; by the time the article is finished it becomes the most important thing in my narrow little life... at least while I'm in front of the keyboard.

So, what would you like to see researched? A few that are all ready on the burner:
  • Dehumidifiers (draft in progress).
  • Diesels additives (draft submitted).
  • Joker valves and chemicals (draft in progress and 50% of trials complete).
  • Mildew preventatives, both coatings and vapor-type (tests started).
  • Water repellant treatments for canvas. Long-term (collecting materials).
  • Flexible window materials (Strata Glas etc.) and waxes. Long term (collecting materials).
  • Follow-up on sanitary hose (write in spring).
  • Follow-up on holding tank vent filters (write in summer).
  • Followup on gasoline and diesel vent filters (write in fall).
Your list, here. anything. I'll pass them along.

  •  Long term tests of Canvas. Color, abrasion, strength. Would take 5 years minimum; my mainsail cover is 16 years old. Ouch. Hard to accelerate.
  •  Same for coated products.
  •  Polyethylene pipe for sanitary use.

Sunday, January 20, 2013

Potomac Archaeology

A walk in the woods can be about the big picture, the small picture, or simply collecting thoughts. The small picture is often lost to the masses.

When I pointed out this neolithic rock art site to a friend of mine, he described the Native Americans responsible--respectfully--as early graffiti artists. Or did the glyphs have some more spiritual meaning? Can't say, though I'm guessing the teenagers that have since decorated this rock never noticed the faint older markings. The light needs to be just so. While rock art is common place in the desert southwest, it is quite rare in the mid-Atlantic area.

The Park Service archaeology group estimates this site at about 5000 BCE, though these sort of markings are inherently difficult to date; there are no other artifacts--the area is flood prone--and there is no carbon dating to nail it down. Weathering and style are the only guides.

Here we find a sequence of 4 figures (one was too faint to reproduce in 2 dimensions) in various stages of throwing spears with an atlatl. There may have been a rendering of prey or some other part of the story, but a piece of rock may also be missing. There is one grove in the rock that may be a spear in flight (not shown here).

Although they have been painted over, they have not been vandalized. There is one partial newer image added by a visitor no doubt. It's well of to the side and no harm was done.

I leave you with a teaser. I located this site by examining some photographs posted in a local news paper about 10 years ago. I knew the creek and I matched the pattern of trees. It's a bit off the trail, perhaps a large part of why it is still there.The Park Service doesn't talk about it. We've also found arrowheads laying on the beach from the same period (pre-woodland)

See what you can find. White folk were not first.



Modern graffiti artists have loitered in the same spot, decorating the the same rock, and no doubt telling their own tales over a few beers. There are always bottles behind the rock. It's not hard to imagine neolithic hunters lingering on the ledge telling lies or searching for meaning. It's been a naturally zen spot for millenia.

Marine Heads--What Chemicals Should I be Testing?

For several months, I've been torturing Joker valves by soaking them in various chemicals to see how they react. Measured are stiffness, change in size, and leakage after exposure. I've looked at...
  • Fresh water
  • Sea water
  • Propylene glycol (25%)
  • Ethylene glycol (25%)
  • Olive oil (98% sea water)
  • Canola oil (98% sea water)
  • Corn oil (98% sea water)
  • Urine
  • Several holding tank treatments
For what it's worth, there is no such thing as a canola plant; it is CANadian rape seed Oil Low Acid. I guess "rape seed" had an image problem.

Scheduled are...
  • Ammonia (since the nitrile valves did not react well to stale urine--they got stiff)
  • Bleach (30% dilution of 3% hypochlorite house hold bleach)
  • Vinegar
  • CLR (dilute lactic acid--5% as used)
  • Baby oil
  • Super Lube
  • Water proof bearing grease
  • Methanol-based antifreeze
  • Lysol toilet bowl cleaner
Manual head joker valves from left to right: Jabsco, Groco, Raritan

 Does anything else come to mind? Some cleaner that some one might actually use? So far, all are demonstrating considerable chemical resistance, though pluses and minuses are appearing. The material is either neoprene (Jabsco) or nitrile (Raritan and Groco). Which is doing better? Mixed results, depending on the chemical.

Wednesday, January 9, 2013

Speak English!

Underweigh: a ship that has weighed anchor, whether under canvass, adrift, or under tow.

Underway: a ship that is making way through the water.


As this would be spoken, at any time when the difference was important, what is the value of the distinction?