MIL-T-13291 Tank, Hot-Dip, Directly And Indirectly Heated

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MIL-T-13291F

from 5 to 10 cubic feet not less than 1 inch and larger than 10 cubic feet

1-1/2 inch nominal pipe size.

The drain shall embody a valve and permit

Type I directly heated tanks

attachment of standard threaded pipe fittings.

shall have heating units attached to the bottom of the dip compartment and no

less than two sides. The side mounted heating units shall be located in the

area between the compartment bottom and 2 inches below the dip material level

with the dip compartment filled to 75 percent of capacity.

When specified,

tanks with dip compartment capacities of 150 gallons or less shall be provided

with an overflow drain. The location of the overflow in the tank and overflow

The overflow requirements of

pipe size shall be as specified (see 6.2.1).

tanks having dip compartment capacities greater than 150 gallons shall conform

to the requirements of OSHA. There shall be no permanent deformation of the

tank or leakage when the tank is filled with applicable material. The tank

shall have a fill line to denote the maximum no load liquid or solution.

3.6.3 Heat transfer fluid jacket. Type III hot-dip tanks shall have a heat

transfer fluid jacket fabricated of sheet steel of the thickness of not less

than specified for the dip compartment (see 3.6.2). All seams shall be secur-

ed and there shall be no permanent deformation of the jacket or leakage of

heat transfer fluid from the jacket when filled to its maximum working level.

The jacket shall permit uniform heating of the bottom and four sides of the

dip compartment to a height of 1 inch above the dip material upper working

The jacket shall be provided with a filler opening and cap not less

level.

than 1-inch nominal pipe size. The jacket shall be vented to preclude pres-

A drain not less than 3/4-inch nominal pipe size

sure buildup due to heat.

shall be provided at the lowest part of the jacket. The drain shall embody a

valve and permit the attachment of standard threaded pipe fittings. Construc-

tion of the jacket shall prevent contact between heat transfer fluid, dip

and insulation during filling, draining, normal operations, and

material,

shipment.

The heating units shall be located in the lower two-thirds of the

area between the jacket bottom and heat transfer fluid level.

3.6.4 Heating units. The heating units shall be of sufficient capacity to

conform to the requirements of 3.5. The units shall be electrically insulated

from the tank and shall be readily accessible for servicing or replacement

without use of special tools.

A removable cover or covers with gasket and

conduit connector shall be fitted over the heating units to prevent entrance

of flammable liquids and vapors. The cover shall be insulated to prevent heat

loss.

3.6.5 Insulation. Each hot-dip tank shall be completely insulated on all

four sides and the bottom with not less than three inches of nonsettling

The tank outside jacket covering the

fiberglass or rockwool material.

insulation shall be fabricated of sheet steel of not less than 14 gauge.

3.6.6 Cover, removable.

Unless otherwise specified (see 6.2.1), the tank

shall be equipped with an insulated removable cover which shall fit the inside

dimensions of the tank and rest on a suitable heat resisting gasket securely

attached to the cover. The cover shall be equipped with suitable handles.