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  1. #61

    Red face cutting open drums

    Hello I used a saber saw wth a metal blade to cut the top off a oil drum, worked great only took about 5 minutes and I am still here to talk about it ! LOL!

  2. #62
    Join Date
    Oct 2012
    Location
    Portland, Oregon
    Posts
    6

    Default A lot of dangerous mis-information, except for entry by twk5 on 8-5-2012

    There is a wealth of well intentioned, but dangerous erroneous advice on this thread.

    The wisest contribution is from member "twk5" on on 8-5-2012; this person clearly understands the process. Many (but not all) of the others are applying "reason" and "logic" to the problem without fully understand the physics and chemistry of the problem of unintended vapor explosion. The suggestions about removing bungs and proceeding worry-free are the most irresponsible; suggestions describing displacing air with water are sound advice, but don't go far enough; suggestions to give a thorough cleaning of the oil drum are on the right track, but likewise don't address displacing any remaining fuel/air vapor.

    Member tkw5 clearly knows what he's talking about and obviously has much training and experience. Any hydrocarbon mixed with oxygen in the right range of concentrations will detonate (explode) if ignited. Ordinary flour finely mixed with air can explode, powdered sugar and air can a really explode violently, as can any hydrocarbon-based oil vapor.

    I've use plasma and oxy-acetylene to decommission and remove underground fuel oil storage tanks. The same methods can be applied to oil drums. Two tricks to avoiding an explosion or fire are either: 1) Displacing most of the oxygen, so the the oil vapor remaining has nothing to burn with; 2) Flushing the drum with so much air that too little fuel/air vapor remains to support combustion. In other words, flood the drum with a relatively inert gas, like CO2, or fill it with water; or drive the oil vapor out of the drum with large continuous volumes of compressed air.

    To learn how to safely cut or weld any fuel oil tank see American Petroleum Institute publication RP 1615 : Installation of Underground Petroleum Storage Systems-Fifth Edition or RP 1614: Closure of Underground Petroleum Storage Tanks-Third Edition, for the proper methods of inerting tanks prior to welding or cutting. In practice, I put 10 pounds of dry ice per 500 gallons of tank capacity into the tank to be removed, which normally has 30 to 70 gallons of oil and sludge still in the tank bottom, then wait a half hour. The oil and sludge act as a heat source to cause the dry ice to sublime into CO2 gas. The CO2 gas generated is heavier than air, forcing the lighter air out the ports at the top of the tank. Part of the trick is to keep air from getting back in; for example the plasma torch jet is an air source unless a nitrogen generator is used. It's okay if a little air gets into the tank while it's being cut into pieces as long as the dry ice subliming in the bottom of the tank produces enough CO2 gas to carry away the air injected by the plasma torch jet.

    And yes, I have experienced a few very small explosions. Hot dross and slag vaporized oil sludge, too much CO2 seeped out of the cuts down and across the tank, allowing a small pocket of air/vapor to float at the very top of the tank. On the next cutting pass, the plasma jet ignited the vapor with a heavy "THUMP", bending open some of the kerfs, causing no damage, but a big scare.
    Last edited by jpcallan; 11-20-2012 at 03:01 PM. Reason: Clarify leading paragraph.

  3. #63
    Join Date
    Apr 2010
    Posts
    270

    Default

    I did the math the other day and came up with one lb. of dry ice for the 55 gal. Pennzoil drum we're going to cut open. The local grocery store has dry ice from Airgas.

  4. #64

    Default Oil drum cutting

    Hi all Thought it time for a heads up caution on this activity. A work colleague was using an angle grinder with a 1mm cutter disc to cut open 200.

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