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Manual Manufacturing Chemists’ Association, Inc. Tolylene Diisocyanate
Sheet
SD-73

is recommended for tank padding. Also acceptable be plugged with ureas. All storage areas should be
is dry air (—40°F. dew point). provided with an automatic sprinkler system.
(c) A filter should be located in the line Drums should be arranged in an orderly man­
between the tank car unloading equipment and the ner. Rows of drums should not obstruct doorways
storage tank into which the tolylene diisocyanate is in case a hurried exit from the storage area is
to be discharged. This will remove any solids that necessary.
may be present.
7.6.2 Bulk Storage
7.5.2 Return Precautions
7.6.2.1 All tanks in which tolylene diisocya­
Empty tank cars should be returned as promptly nate is stored must be blanketed with a dry gas,
as possible, in accordance with instructions received such as nitrogen, or with dry air (—40°F. dew point).
from the shipper. The shipper’s routing instructions This will prevent the reaction of any moisture that
should always be strictly followed. could otherwise be present with the isocyanate to

7.6 STORAGE 7.6.2.2 Heating may sometimes be necessary
because the 2,4 tolylene diisocyanate isomer will
7.6.1 Indoor Storag begin to crystallize out at temperature below 70°F.

Indoor storage areas should be dry, fireproof, 7.6.2.3 Tolylene diisocyanate in storage tanks
and adequately ventilated. It is desirable that floors should be thoroughly stirred before being pumped to
be pitched to trapped floor drains. If drains are processing equipment. This is necessary to assure
not provided, four inch curbs or a drained gutter, uniformity of isomer composition (when both the
covered with an appropriate grill, should be con­ 2,4 and 2,6 isomers are present), because stratifica­
structed at door openings. In' areas where spillage tion into isomer layers will-result if at any time the
is likely to occur, a drained gutter arrangement is storage tank has been cooled enough to cause the
preferable since a trapped floor drain would soon material to begin to freeze.

8. TANK AND EQUIPMENT CLEANING AND REPAIRS

8.1 PREPARATION OF TANKS AND EQUIP­ leading in and out of the tank should be blanked
MENT off or disconnected. If an agitator is used, it should
be locked out at the main cut-out.
8.1.1 Tank and equipment cleaning should be
under the direction of thoroughly trained personnel
who are fully familiar with all of the hazards and 8.2 ENTERING THE TANK
the safeguards necessary for the safe performance
of the work. 8.2.1 No one should enter a tank or confined
space until a work permit has been signed by an
8.1.2 Process equipment shpuld not be repaired authorized person indicating that the area has been
when in operation. Lines should be drained and tested and found to be safe.
then blown dry with a dry inert gas such as nitrogen,
if practicable. Workmen should wear appropriate 8.2.2 No workman should enter a tank or vessel
protective devices (See Section 5.2). Any spills that does not have a manhole opening large enough
from lines or equipment should be cleaned up im­ to admit a person wearing a safety harness, life
mediately. (See Section 7.2.2.) line, and emergency respiratory equipment. It should
be ascertained that the tank or vessel can be left
8.1.3 A tank that is to be entered should be by the original entrance. A man outside the tank
drained and then flushed with solvent. It is prob­ should keep the man in the tank under observation
ably most convenient to use the process solvent for at all times. Another man should be available near­
this purpose, although any other conventional or­ by to aid in rescue if necessary. •
ganic solvent may be used, providing it is not too
flammable. The tank should then be filled with 8.2.3 A supplied-air respirator or self-contained
water once or twice and drained to remove vapors. breathing apparatus, together with rescue harness
After a purge with fresh air, a check should be and life line should always be located outside the
made to determine whether any vapors remain. If tank for rescue purposes, regardless of the type of
not, and if a further test for oxygen sufficiency proves respiratory equipment or air supply which is pro­
satisfactory, the tank is safe to enter. All lines vided for employees inside the tank.

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