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An Acceptable Repair or Wimping Out?

Discussion in 'Ask All Sailors' started by rardiH36, Oct 5, 2017. Add this thread to a FAQ

  1. rardiH36

    rardiH36

    Joined Jun 21, 2007
    2,029 posts, 30 likes
    Hunter Cherubini 36_80-82
    US San Francisco Bay's "Hurricane Glitch"
    Looking for suggestions or alternatives to the situation described below.

    My 37 year old aluminum 30 gallon diesel fuel tank located on a OEM shelf near the port side lazarette seat has finally started to leak. Very slowly though. A single sheet of paper towel in the aft end of the bilge absorbs the leak rate over the course of a month.

    The location of the leak at the tank can’t be reached for any sort of outside repair with epoxy. Anyway, I expect that more pinhole leaks will appear over the next few years. So repairing is probably a fool’s errand.

    The only way I can remove the tank in one piece is by reciprocating saw surgery to my cockpit liner. Not a happy option.

    I am thinking to:

    - Empty the offending tank of diesel using the in-line electric fuel pump (installed by a PO to aid bleeding the system). Then add a bit of water. Drain again. H2O once again for good measure.
    - Use my reciprocating saw to cut the tank apart so I can remove it and clear the space. Donate the tank to the local aluminum recycler.
    - Replace it with a Moeller “Roto-molded, cross-linked polyethylene” plastic tank with dimensions to fit in the existing space through the lazarette seat opening. The tank probably will be less than 30 gallons … But I don’t need anywhere that capacity for the type of sailing I do.

    Another option is just to drain the tank. Decommission it but leave it in place. Instead, install a new tank on the starboard side where I have a currently empty space.
     


    Last edited: Oct 5, 2017
  2. SG

    SG

    Joined Feb 11, 2017
    491 posts, 53 likes
    J/Boat J/160
    US Annapolis
    You need to put an inert gas into the tank after you drain it unless you want to become a Darwin Award recipient. The vapors with a spark could be fatal. (Classic construction accident that usually ends very badly.)
    You could steam clean the tank after draining it too. NO VAPORS of petroleum products before the saw.

    My advice, which you know in your heart of hearts: Yes, get the tank out and replace it. It doesn't owe the boat anything. It's time.
     


    Gunni likes this.
  3. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    Gas or diesel?
     


  4. capta

    capta

    Joined Jun 4, 2009
    1,924 posts, 295 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    "My 37 year old aluminum 30 gallon diesel fuel tank"
     


  5. Gunni

    Gunni

    Joined Mar 16, 2010
    4,350 posts, 565 likes
    Beneteau 411 Oceanis
    US Annapolis
    Yes, take the fuel out, add dry ice to fill it with CO2 vapor, you will see the off gas vapor. Cut away. Need to ventilate the work area as CO2 will fill your tub and create an oxygen deficient atmosphere. Best practice would be pneumatic shears.
     


    JamesG161 likes this.
  6. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    Thanks. Then the Darwin Award remarks are unnecessarly alsrmist. You can throw a lit match into diesel and it will just go out.
     


  7. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    Ridiculous. It's diesel, not gas!
     


  8. Ross S

    Ross S

    Joined Oct 20, 2011
    89 posts, 11 likes
    Precision 21
    US Great Sacandaga Lake
    Respectfully disagree. Diesel still evaporates and in the right conditions can form an explosive mixture.

    This is a better safe than sorry situation.
     


  9. SG

    SG

    Joined Feb 11, 2017
    491 posts, 53 likes
    J/Boat J/160
    US Annapolis
    What me worry.jpg
    Diesel vapors in a tank will explode, jviss.

    Darwin Award stuff. You might not have it happen -- but if it does...

    Dry ice or nitrogen are the the two most used gases to displace the oxygen. On construction sites, we have to deal with this all the time to cut-up an old tank and remove it -- or to cut a new port.

    https://app.aws.org/forum/topic_show.pl?tid=31041
     


    JamesG161 likes this.
  10. Richard19068

    Richard19068

    Joined Jun 11, 2004
    597 posts, 13 likes
    Oday 31
    US Redondo Beach

    LCO-47: Diesel Fuel Vapor Hazards
    by Vickie Hoffart

    Most off-road machinery is diesel-powered. Diesel fuel is widely regarded as safe to handle and store. In its liquid form, that is true for the most part. In its vapor form, diesel is very dangerous and can catch fire (or explode) easily in the presence of an accelerant such as fan air or oxygen.

    Diesel is a stable liquid at normal outdoor temperatures. At temperatures above 100 degrees, the diesel liquid can begin to vaporize. The vaporization rate increases as the temperature increases.

    Diesel vapors can ignite and explode when mixed with air. The vapors are explosive over a wide vapor-to-air mixture range. The lower explosive limit is less than 1%, and the upper explosive limit is about 10%. That means that diesel fuel vapors from a storage tank can explode with as little as 1% of the air being diesel fuel vapors.

    Welding on a fuel tank is one commonly encountered hazard associated with diesel fuel. If the tank contains diesel vapors, a welding arc can easily cause an explosion.

    Tank repair explosions have occurred with storage tanks, vehicle tanks, and machinery tanks. OSHA regulations specifically prohibit performing welding or cutting in the presence of explosive vapors. (See OSHA Standard 1910.252 for general safety requirements related to welding, cutting, and brazing: www.osha.gov/SLTC/weldingcuttingbrazing/)

    One way to prevent an explosion of diesel vapors during weld repair of a tank is to remove all the fuel and vapor from the tank. If available, fill the tank with an inert gas such as argon or carbon dioxide (dry ice can be used, too) to eliminate the diesel fuel fumes. The liquid fuel should be completely removed and all of the vapor should be purged. Sniffers are a readily available tool and are required for testing for the presence and concentration of fuel vapors.

    There are documented instances of a person using a pocket lighter as a light source to look down into a diesel fuel tank to check the fuel level. NEVER use or bring an ignition source anywhere near a fuel storage tank or fuel storage area!

    The consequences of a diesel vapor explosion include severe injuries and fatalities. Treat diesel fuel in the same manner as gasoline or any other volatile fuel. Keep fuels and ignition sources separate.

    Reviewed by:
    Vickie Hoffart, FRA Lake States & Western Regions Manager
    Prepared by the Southwide Safety Committee, Forest Resources Association Inc.
    Please follow equipment manufacturers’ recommendations for safe operation and maintenance procedures.
     


  11. Skipper

    Skipper

    Joined Oct 9, 2008
    1,338 posts, 138 likes
    Bristol 29.9
    US Dana Point
    I'm hesitant to believe that the mfg would allow that the tank can't be removed in one piece.
    What if you unbolted the shelf?
    Are there bulkheads or panels that appear permanent but that can actually be unbolted?
     


  12. Apex

    Apex

    Joined Jun 19, 2013
    603 posts, 40 likes
    Oday 28
    US Muskegon
    What about a fuel bladder in the old tank?
     


  13. jviss

    jviss

    Joined Feb 5, 2004
    1,811 posts, 102 likes
    Tartan 3800
    US Westborough Westport, MA
    I stand corrected. Who knew? The USCG doesn't require blowers or flash arresters for diesel engines, and the fuel safety relative to gasoline is one of the great attractions for these in boats. And yes, my home heating technician demonstrated by tossing a lit match into a bucket of diesel. Oh well!
     


  14. Ross S

    Ross S

    Joined Oct 20, 2011
    89 posts, 11 likes
    Precision 21
    US Great Sacandaga Lake
    Diesel fuel is safer than gasoline primarily due to the much higher flash point. However, you can also extinguish a lit match into a bucket of gasoline in the right circumstances too.

    In my opinion the problem present in this thread was that the person was considering cutting their tank out of their boat. Depending on how they cut it, that process could generate significant and sustained heating which could lead to the creation of a flammable mix of vapors.

    It's a situation of "less dangerous" not being the same thing as "safe".
     


  15. capta

    capta

    Joined Jun 4, 2009
    1,924 posts, 295 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    Oh yeah, there you go. I've seen boat manufacturers seal air conditioning units behind settees where the only way to replace the units was to remove the whole settee, unplugging the screws in the bright work. I've seen pumps laid under a floor before it was assembled and forget a hatch. On my boat you can't remove any of the tanks, fuel or water without completely tearing apart the salon flooring and the supports. Most boats require some pretty serious disassembly if you want to replace the engine, and that, like tank replacing, is something almost every boat will require at some point.
    I think you give boat manufacturers way too much credit for any thought about repairs or replacing things like tanks. Most couldn't care less, once they've got your money.
     


    Parsons, Alan Gomes, Skipper and 2 others like this.
  16. Ned Ludd

    Ned Ludd

    Joined Apr 4, 2016
    184 posts, 69 likes
    Newport 28
    US Oregon Richardson Marina
    The tank in my boat was installed before the interior liner, only access is a 12 x 12 hole. To actually answer the OP's question: remove the old tank safely buy cutting up (metal shears was a good recommendation) and install a new smaller one. You will be glad for any newly created storage space.
     


  17. rardiH36

    rardiH36

    Joined Jun 21, 2007
    2,029 posts, 30 likes
    Hunter Cherubini 36_80-82
    US San Francisco Bay's "Hurricane Glitch"
    Thanks all for the responses.

    In particular the combustible dangers of diesel in a vapor state. There are other products that one doesn't associate with blowing up. In my prior life, I frequented steel and metal plants. Best practice at the plants was to shut them down on a regular schedule for a thorough cleaning of all the metal and other by-product dust particles that would settle around inside the factory space. Only to be easily kicked up into the air. In certain conditions the aerated dust becomes explosively combustible in a confined space.

    Another Question now that explosive vapors have been indentified as a concern: If I opt to leave my leaking diesel tank in place, and simply install a new one one the other side, aside from draining and flushing a few times with water, what would be the practice for decommissioning the old tank? I ask because I know that one of the most dangerous conditions on oil/fuel/chemical tankers are the tanks/holds that have been total emptied of the product. The tanks need to be then washed and blowers fitted to vacate any residual vapors.

    Skipper: I will take another more creative look if the tank can be eased out in any direction. But I have looked at it quite a bit. The only way to slide it out would be to cut out the bulkhead, the molded-in fridge box and part of the interior liner and wood work. Definitely easier to cut apart the tank. But also the easiest is to leave it in place. An just install a new one somewhere else. I suspect the tank was installed/afixed by Hunter. Then they dropped/attached the upper deck molding.
     


  18. CaptKimble

    CaptKimble

    Joined Jul 29, 2017
    46 posts, 8 likes
    Catalina 380
    US San Pedro Los Angeles
    On the subject of explosive vapors etc. Google the sugar plant explosion in Savannah GA. That was sugar dust that killed all those people. Who da thunk it?
     


  19. Justin_NSA

    Justin_NSA

    Joined Jul 7, 2004
    3,910 posts, 366 likes
    Hunter 30T
    US Wichita, KS
    It's surprising sometimes what becomes dangerous and explosive. We get grain elevator explosions once in a while around here. Mostly wheat dust. Cardboard dust can explode too ! Fumes and dust are more volatile than liquid or solids.
     


  20. thinwater

    thinwater

    Joined Mar 26, 2011
    1,543 posts, 146 likes
    PDQ Altair 32/34
    US Deale, MD
    Bull. I've seen two diesel tanks blow up when cut on. I've also seen many many get away with it. But I saw a man thrown into the air and another tank stretched by over a foot. I've done accident investigations on several others.

    Yes, diesel will only burn, but cutting creates mist and generates heat. Either fill it with water or add dry ice.
     


    Alan Gomes likes this.

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