Discussion Central

  • 1.  Vapour Barrier_ Construction sites within vicinity of Fuel Tank Farm

    Posted 10-07-2020 20:45
    Hello, Can someone advise please.
    For a construction site that is contained within the vicinity of fuel tanks and knowing the hazardous nature of such an area ; does it need some sort of extra vapour barrier around the construction site? 

    Thanks!!



  • 2.  RE: Vapour Barrier_ Construction sites within vicinity of Fuel Tank Farm

    Posted 10-08-2020 00:11
    Hi,

    To my knowledge, fuel oil stored at ambient conditions will not release high vapor flow rates and flammable vapor content during the normal outbreathing of the tank. I will however, refer to NFPA 30 on area classifications and for maintaining a safe distance from the construction site.

    Regards,

    ------------------------------
    Shantal Ramdeo PE
    Senior Process Engineer
    Heritage Petroleum Company Limited
    Princes Town
    ------------------------------

    Original Message


  • 3.  RE: Vapour Barrier_ Construction sites within vicinity of Fuel Tank Farm

    Posted 10-09-2020 05:26
    Hello,

    There have been many fires as a result of construction activities near fuel storage tanks in the past. Out gases from breathing fuel tanks are normally too rich to burn inside the tank but in the atmosphere, as the gases disperse, they go through the flammable envelope. Normally the way these are prevented are to remove the ignition source and by location.

    Hot work of any kind can introduce a new hazard. Depending on storage tank operations like filling storage tanks with fresh, maybe slightly more volatile, fuel, cautions must be taken. High quality hot work permits with ongoing coordination to operations and continuous air monitoring for flammable gases may be required. It may be necessary to empty, stop fuel tank use and inert the tank with nitrogen for some steps in the construction. It all depends on physical distances per area classification, operations and weather conditions, too.

    I do not know of any vapor barriers that could be used to safely separate the tank vent gases from adjacent construction activities. Remember, hydrocarbons are typically heavier than air.

    Vapor barrier is a term typically used for film type materials used under concrete slabs or in walls and in food/other packaging film.

    Regards,
    Gary Koehler
    Brownsville, TX


    Original Message


  • 4.  RE: Vapour Barrier_ Construction sites within vicinity of Fuel Tank Farm

    Posted 10-09-2020 11:32
    It is a myth that the vapor pressure of fuel oil is too low to generate an explosive concentration of vapors.  These days, vacuum residual is cut with off-spec light ends to make six oil and the vapor pressure of the mixture is not negligible.  On top of that, compounds like phosgene have been found in the headspace of heated tanks, which indicates that cracking occurs.

    Don't trust the default vapor pressure values with anyone's life.  There is no standard test method for measuring the vapor pressure of heavy refinery liquids that has a precision statement so we are flying blind.

    This insulated tank exploded in May when someone was welding nearby.  Here is a story about an asphalt tank exploding because of improper work practices (asphalt is heavier than six oil).  There is no comprehensive source of information about accidents like this.  Too bad.

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    -Kirsten

    Kirsten Rosselot
    Process Profiles
    Calabasas, CA United States
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    Original Message


  • 5.  RE: Vapour Barrier_ Construction sites within vicinity of Fuel Tank Farm

    Posted 10-09-2020 13:14
    All,

    Kirsten is correct and there is variability in natural materials. So, one test will not necessarily represent a lifetime on products. Which version did you get today?

    Regards,
    Gary


    Original Message


  • 6.  RE: Vapour Barrier_ Construction sites within vicinity of Fuel Tank Farm

    Posted 10-12-2020 15:28
    Hi all,
    Appreciate your views on this subject. Thanks!

    Grace

    ------------------------------
    [Gracia] [Une]
    [Chemical & Biological Engineering ( Graduate)]
    [OSM Consultants]
    [Samoa]
    ------------------------------

    Original Message


  • 7.  RE: Vapour Barrier_ Construction sites within vicinity of Fuel Tank Farm

    Posted 10-08-2020 09:45
    It depends upon the tanks and the piping.  Since about 1988 or thereabouts, all fuel tanks were required to have double walls if steel, or in tank vaults, and they were required to have overfill protection and periodic testing of the yard piping.
    Unless there is a specific reason for it, I would not recommend a vapor barrier between the construction site and the gas tank storage area.
    If you are concerned, and if groundwater is shallow enough, consider digging a slit trench between the construction site and the tanks, and laying in corrugated piping and then back filling the trench with porous gravel.  You could even connect the piping to the surface via an elbow.  That should handle any concerns

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    [David] [Russell] [PE]
    [President]
    [Global Environmental Operations, Inc.]
    [Liburn] [GA]
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    Original Message


  • 8.  RE: Vapour Barrier_ Construction sites within vicinity of Fuel Tank Farm

    Posted 10-09-2020 08:54
    There are many safety guidelines on what vapor barrier is required on a construction site. AIChE Beacon guides, API regulations, company safety standards will have what you want. Your company's insurance company  will also help. You have taken the right safety direction which should ensure that no incident happens.


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    Louis Mielke
    Chemical engineer
    Johannesburg
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    Original Message