Stainless or Aluminum for diesel fuel tanks?

Discussion in 'Powerboats' started by Timberwolf, Jul 13, 2010.

  1. Timberwolf
    Joined: Jun 2010
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    Timberwolf Junior Member

    I have seen lots of discussion on how to mount tanks, but not much about the tank(s) themselves!
    Which materialis best and why?
    Anyone care to recommend a fabricator to buy tanks from?
  2. TeddyDiver
    Joined: Dec 2007
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    TeddyDiver Gollywobbler

    Polyethylene if find one that fits.. Second choice epoxy/glass.. Metal for day tank..
  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Aluminum is better than stainless. You can find many threads on the subject. Depending on the size, plastic is a good option.
  4. rasorinc
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    rasorinc Senior Member

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    FAST FRED Senior Member

    "Polyethylene if find one that fits.."

    The poly tank takes a bit of fitting.

    After it is laid in place , it needs to be fuel filled.

    They expand a bit , then it is strapped or simply foamed in place on the boat.

  6. Ike
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    Ike Senior Member

    Aluminum. Stainless is fine for small cylindrical tanks but not good for large tanks with lots of welds. SS suffers friom crevice corrosion which is usually in the weld seams. The more welds the more chance of crevice corrosion. Aluminum has it's own problems. Build a decent mounting system that keeps all sides including the bottom of the tank exposed to air and dry.

    But the best are Polyethylene tanks. No corrosion, no seams (if it is a rotomolded tanks) and it isn't affected by anything in the fuel. Alcohol and other additives won't touch it. Thes tanks last virtually forever. But again, you need to allow for tank expansion (about 3% in volume) and the tank has to be well strapped down. The drawback? No baffling, unless you build a PE tank with welded seams. then baffling can be installed.
  7. Willallison
    Joined: Oct 2001
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    Willallison Senior Member

    Yep... PE would definitely be my 1st choice.
    I had a 525L PE tank custom made recently - with baffles. The Wall thickness was greater than typically found on rotomoulded PE tanks, so it was heavier than would otherwise have been the case. But the upside is that it expanded much less.
    It was such a work of art that I very nearly kept it and used it as a coffee table!!
  8. mark775

    mark775 Guest

    What is the fire rating of this polyethylene?
  9. raw
    Joined: Jul 2006
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    raw Senior Member

    The answer depends on any or all of the following: type of fuel, size of vessel, type of vessel, classification requirements, size of tank, vessel construction, price, availability and the arrangement of the space in which the tank is to go.

    Easy huh? Make sense?
  10. mark775

    mark775 Guest

    Okay then, for a given thickness, at what temperature is it tested to survive for how long?
  11. Ike
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    Ike Senior Member

    I don't know the exact fire rating, but PE gasoline tanks have been tested for fire resistance by Underwriters Laboratories and Imanna Labs. they have passed the USCG and ABYC requirements for surviving a 2 1/2 minute fire test without leaking. Simply put ( the test is more complex) they are filled with gasoline, and engulfed in a fire for 2 1/2 minutes. They are then pressure tested. If they leak they fail.

    None have failed.
  12. raw
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    raw Senior Member

    Sorry Mark, my post was not a response to your question. I was trying to point out that more information would be required from the original poster to get a good answer.

    I have designed many fuel tanks in steel, stainless steel, al, FRP, both integral and free standing from say 75L through to 5000L (plus one barge that had integral tanks of 35000L) plus a couple of small PE ones and in each case the material selected was the right one for the job at hand. The original questions is simply put, too broad to give an answer that is 100% correct. I would however most likely lean toward Al in most cases....
  13. Manie B
    Joined: Sep 2006
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    Manie B Senior Member

    Hi Guys

    in my neck of the woods aluminium or stainless tanks are just way too expensive
    rotomoulded or "plastic" tanks would have to be imported at mega costs

    we would like to build a 1000 litre (200 gal) GASOLINE tank - epoxy glass / aramid with a marine plywood core
    the general idea is that we can build a tank to our shape and size - to coast guard standards - top fill - top suction - top breather - all well ventilated away from the motors - galley - flames - any source of spark AND a 50mm (2inch) space all round from the hull for4 accident damage

    any suggestions ??
    any advice what to do and what not ??
    type of epoxy / glass - type of internal coating / paint - type of core ??
    wall thickness / baffles ??

    the tank will gravity feed to the motors

    1 person likes this.
  14. Ike
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    Ike Senior Member

    My suggestion is don't. There have been significant problems of delamination with fiberglass gasoline fuel tanks. The resins dissolve over time. There are resins that are very fuel resistant but they are expensive and hard to find. I have seen tanks that failed in as little as six months. Most of the failures though were long term use, 10 to 20 years. Alcohol (ethanol) in the fuel make it worse.

    Is this for a boat? Gravity feed is a no go. Gasoline tanks are require to not have any openings below the top of the tank, so the pickup has to be mounted on top and extend down into the tank. This requires some type of pump, usually on the engine to suck the gas. The pump has to be on the engine or within 12 inches of the engine. If you mounted it high enough above the engine to create a siphon, then you would need an anti-siphon valve at the tank

    See for the USCG rules

  15. Tad
    Joined: Mar 2002
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    Tad Boat Designer

    Manie......Ike has given you some good advice....I will note that epoxy and "fiberglass" are often very different things.....

    Here are some general guidelines from the Gougeon Brothers on epoxy/ply tank building......

    View attachment tanks.pdf

    Also I second the gravity feed comment....don't do puts the entire fuel system under pressure all the time.....
    1 person likes this.
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