Tank Closure without Tears Flashcards
What are the three points of the basic fire triangle? (NEIWPCC, p. 2)
How many points of the fire triangle are necessary to support combustion? (NEIWPCC,
p. 2)
Movement of which of the following causes static electricity: liquids, air or solids?
(NEIWPCC, p. 3)
What must be eliminated prior to the use of heavy equipment for handling the tank?
(NEIWPCC, p.3)
If static-producing movement can not be eliminated, how can the contractor provide a “safe” discharge of static electricity? (NEIWPCC, p. 3)
How can electrostatic ignition hazards be reduced when removing product or residue from
the tank? (NEIWPCC, p. 3-4)
Why should plastic (PVC) pick-up tubes be avoided on the stripping lines of vacuum
trucks? (NEIWPCC, p. 4)
Where should the vacuum truck be in relation to the tank when removing liquid or residues
from a tank? Where should exhaust hoses be situated relative to the tank? (NEIWPCC,
p. 5)
How does purging work? Which point of the fire triangle is dealt with in purging the
potentially explosive atmosphere in a tank? (NEIWPCC, p. 5)
What is the flammable range of vapor given off by most petroleum products? (NEIWPCC
pp. 5-6)
Below the lower explosive level (LEL) the mixture of fuel and vapor in a tank is too lean to
support combustion. What is the LEL for petroleum products? (NEIWPCC, p. 6)
What is the goal of purging? (NEIWPCC, p. 6)
How does inerting work? Which point of the fire triangle is dealt with in “inerting” the
atmosphere of a tank? (NEIWPCC, p. 6)
What is the goal of inerting a tank? (NEIWPCC, p. 6)
Why is it especially important to control sources of ignition when purging an underground
tank with air? (NEIWPCC, p. 6)
Which method of purging with air pumps fresh air into the tank and which one draws
vapors out of the tank? (NEIWPCC, pp. 6-7)
When purging a tank, one should NOT use .
(NEIWPCC, p. 7)
Once a tank has been purged, is there any need to continue monitoring it for flammable
vapors? (NEIWPCC, p. 7)
When testing with a Combustible Gas Indicator (CGI), a reading of 100 percent LEL
would indicate that what percent of gasoline vapors were present? (NEIWPCC, p. 8)
What substances can foul or “poison” a CGI probe? (NEIWPCC, pp. 8-9)
When inerting, how can carbon dioxide be generated? (NEIWPCC, p. 9)
crushing and distributing dry ice
When inerting a tank with dry ice, how many pounds of dry ice should be used for every
1,000 gallons of tank capacity? (NEIWPCC, p. 9)
15-20 pounds per 1,000
gallons of tank capacity
What are two ways to reduce the concentration of oxygen in a tank to a level that is
insufficient to support combustion? (NEIWPCC, p. 9)
Dry ice and nitrogen
What readings on an oxygen meter indicate a non-combustible atmosphere in tanks that
have contained most petroleum products? What readings should you target for a more
conservative safety rule of thumb? (NEIWPCC, p. 11)
1-10%
What percent oxygen by volume indicates a safe range for breathing? (NEIWPCC, p. 11)
19.5-21%
Should a single point of the fire triangle be the focus of efforts to avoid fire and explosion
during tank closure? (NEIWPCC, p. 12)
First,
sources of ignition were removed or controlled so
product could be pumped from the tank.
Can a combustible gas indicator be used to monitor a tank which is being inerted? Why or
why not? (NEIWPCC, p. 13)
KEEP TESTING
for the flammable concentration of vapors both in and
around the tank until the tank has been cleaned on-
site, or loaded for transport to be cleaned off-site!
What is the definition of “flashpoint”? (NEIWPCC, p. 13)
the lowest temperature
at which the liquid product gives off sufficient vapors
to support combustion (in the presence of enough
oxygen and an ignition source).
Why is it necessary to check the atmosphere in the tank before cleaning it when the tank
has already been purged or inerted? (NEIWPCC, p. 14
To check if there’s any more vapors
Why should tanks be cleaned regardless of whether they are to be removed or closed in
place? (NEIWPCC, p. 14)
Cleaning the tank will decrease the
amount of vapor regeneration.
What are the primary safety factors to consider when deciding whether to clean a tank onsite
or off-site? (NEIWPCC, p. 14)
The primary
safety considerations have to do with physical
surroundings, air flow and population in the area.
When closing an UST in-place, what is used to fill the tank? (NEIWPCC, p. 15)
UR
Cement slurry and sand
Where is the most dangerous position in relation to a tank if it should explode?
(NEIWPCC, p. 16)
The ends of the tank
What is the procedure for sealing corrosion holes in a tank prior to transport?
(NEIWPCC, p. 16)
Plugs
When transporting an UST removed from a site, how large should the vent hole be on the
top of the tank? (NEIWPCC, p. 16)
1/8 inch
What are the elements of a safe removal checklist? (NEIWPCC, p. 17)
• Make sure that the equipment available is
appropriate for the tank pull.
• Sand well out of the way and behind stable
objects until the tank has been lifted onto the ground
and blocked, or onto the transport truck and secured.
Cables and chains can snap and fly out in any direction.
• Tanks should not be dragged at any time.
• If a tank explodes, the weakest points of steel
tanks are the ends, so stay away from them.
