Hey jha_amin... I found this little bit but I am going to look into it
further later on tonight. Gotta go!

http://vm.cfsan.fda.gov/~comm/transafe.html

Conversion Of Trailers From

"Non-Approved, Non-Food Service" to "Approved Non-Food To Food" and
"Food to Food" Service

(NOTE: There should be clear, legally binding agreement between
carriers, shippers and consignees concerning the use of converted
tankers. All conversion steps should be documented)

Minimum Tank Conversion Steps

The tank should be appropriately cleaned of prior product;

An internal inspection should include determination evaluation and/or
removal of:

Finish (parent metal and welds);
Evidence of pitting;
Corrosion;

Weld and parent material discoloration; and
Odors.

Remove, clean, pacify and/or replace:
Internal and external vents, valves and caps, discs, and piping;
Manifolds;

All gaskets (including those on accessories); and
Tank interior metal surfaces.

A final wash should be performed before applying a seal.

Apply a "Food Grade" decal, cleaning tag, and seals (if required).

Tank Requirements
Non-Dairy Liquid Food Grade Products

The shell, heads, and appliances with product contact surfaces should be
a minimum alloy #304 SS, low carbon;
Weld finish should be W-3;

All parent metal finish on product contact surfaces should be 2B;

The entire tank surface should be clean-bore (no baffles);

If compartments are permitted they should be equipped with double
bulkheads with evacuated airspace between bulkheads;
With the exception of center-discharge (belly drop) tanks, all tanks
should have a positive drain (minimum 4 inch slope from front to back of
tankers).

Accesories and Fittings on Non-Dairy
Liquid Tanks

All internal accessories should be capable of being disassembled to
clean product-contact surfaces.

Internal valves should be acceptable

(note: internal valves are mandatory if food-grade product is flammable
or corrosive liquid).

Clean-out openings should be appropriate.

Gaskets should be removable and non-porous.

Manways, fittings, and connections should be a minimum alloy #304 SS,
low carbon.

Vehicle-mounted product transfer equipment if used, should meet the
requirements established for the tanker.

Product transfer equipment

(vehicle-mounted versus facility-supplied) is a matter of choice
involving the shipper, carrier and consignee. If "vehicle-mounted"
product transfer equipment is used, such equipment should meet the
requirements established for the cargo tank.

If the use of seals is required by the shipper (at loading) such should
be provided and affixed by shipper representatives and should be "cable
type" or equivalent "tamper evident." The shipper should provide
authorized seals to carriers loading from remote rail facilities where
the carrier or a third party acts as the "shipper representative."

Dry-Bulk Food Grade Cargo Tanks

The use of aluminum alloys in the construction of shell, heads, and
accessory equipment is appropriate.
Clean-out openings are appropriate.
All gaskets should be removable and non-porous.

Product transfer equipment - vehicle mounted equipment to accomplish
pressure unloading is appropriate.