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TM 9-2330-272-14
4-64. PURGING TANK (Con’t).
d.
STEAM CLEAN PURGING
WARNING
l DO NOT perform purging operations in an electrical storm or if a storm is threatening.
Keep open flames or other sources of ignition, such as welding and cutting torches
and ordinary electrical equipment, away from area where purging operation is in
progress. Sufficient fire extinguishers must be present and manned. Failure to follow
this warning will result in serious injury or death to personnel.
. Connect bonding and grounding connections before beginning purging operations.
Maintain bonding and grounding connection until after all purging is completed.
Connections must be made to clean, unpainted surfaces. An unbended and
ungrounded or improperly bonded and grounded semitrailer could produce a spark.
The resulting explosion will cause serious injury or death to personnel.
l Personnel engaged in purging operations must not wear wool, nylon, silk, rayon, or
other clothing that generates status electricity. Wear clean cotton clothing with no
metal zippers. Remove all contents from pockets. Wear rubber boots and gloves to
keep fuel off skin. Use cotton cloths for cleaning purposes. Before climbing onto
semitrailer, grasp static ground wire to discharge all static from body.
. Give IMMEDIATE medical attention to personnel exposed to hydrocarbon or toxic
vapors. Signs of distress are weakness,
nausea, coughing or intoxication,
nosebleed or cramps, or other unusual symptoms. Qualified personnel able to
administer artificial respiration and simple first aid must be present.
l Should an emergency arise requiring entry into a tank which is not vapor-free, or
which has an oxygen content less than 19.5%, personnel entering must have an
attached lifeline and wear protective respiratory equipment in the form of
self-contained breathing apparatus or a full facepiece mask with a pressure supply of
breathable air. Another person, also provided with respiratory equipment, MUST be
stationed at manhole opening and remain there with full ability to watch personnel
inside tank and summon assistance in the event a rescue operation is needed.
Personnel MUST NOT enter a tank which is in the explosive range.
l If semitrailer is Ieft overnight after purging procedure, retest with combustible gas
indicator set to ensure a SAFE reading. Tanks may recharge themselves with
seepage of undetected pockets of vapors. Failure to follow this warning may result in
serious injury or death to personnel.
NOTE
This method is an alternate to chemical method. If is effective for the removal of high
viscosity petroleum products. Low pressure steam is injected into tank for a period of
time to bring the temperature of tank to 76°C (170°F).
1.
Ground semitrailer to steam cleaner. Ensure that semitrailer bonding and grounding connections are made
(para 2-13).
2.
After draining tank, ensure that all valves and drain points remain open.
3.
Introduce steam through manhole openings in sufficient volumn to raise temperature of tank to 76°C (170°F).
Close manhole fill covers as far as steam lines wiII permit.
4-134
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