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Flanged only heads

The formed head most economical to fabricate is that produced by simply forming a flange with

radius on a flat plate. This head is identified as a flanged-only head and is illustrated a of fig 5.7the

radius of a flanged-only head decreases somewhat the abruptness in change of shape at the junction of

the flat head and the cylinder. The resulting gradual change in shape local stresses.

The flanged-only head finds its widest application inclosing the end of horizontal cylindrical

storage vessel at atmospheric pressure. These vessel typically store fuel oil, kerosene, and

miscellaneous liquid having low vapor pressure. Flanged-only heads may be used for the bottom heads

of vertical cylindrical vessel that rest on concrete slabs and do not have diameters in excess of 20 ft.

these heads are fabricated on the basis of using the outside diameter as the nominal diameter. Head

diameters based on the outside diameter are available in increments of 2 in. from 12 to 42 in.

increments of 6 in. from 42 to 144 in. and in increments of 12 in. from 144 to 240 in. a head with a 246-

in. outside diameter is also available.

Flanged standard dished and flanged shallow dished heads.

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Typical application of these head occur in the construction of vertical vessels for low pressure, of

horizontal cylindrical storage tanks for volatile fluids such naphtha, gasoline, and kerosene, and of large-

diameter storage tanks in which the vapor pressure and hydrostatic pressure is too great for the

practical use of flanged-only heads. Vessel with Flanged and shallow dished heads are primarily used forhorizontal storage tanks.

Elliptical dished Heads

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Used in preference to code flanged and dished heads form with two radii for many vessels

designed for pressure in range of 100 psi and for most vessel designed for pressure over 200 psi. the

elliptical dished heads are formed on dies in which the diametrical cross section is an ellipse. If the ratio

of major to minor.

Hemispherical heads

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For given thickness, Hemispherical heads are the strongest of the formed heads. These heads can

be used to resist approximately twice the pressure rating of an elliptical dished head or cylindrical shell

of the same thickness and diameter. The degree of forming and accompanying cost are greater than for

any of the heads previously described; also, the available sizes formed from single plates are more

limited. A great variety of hemispherical heads diameters and gages are available in segmental form and

can be field or shop welded.

Conical heads

Used as bottom heads for variety of process equipment such as evaporators, spray driers,

crystallizers, and settling tanks. The particular advantages of the use of conical bottoms lies in the

accumulation and removal of solids from such equipment. Cones having an angle at the apex of 60o

are

commonly used for removal of solids. Grearer angles may cause accumulation of solids as a result of the

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fractional resistance between the solids and the inside cone surface. Another common of conical section

is for changing the diameter of cylindrical shells; this is often necessary in some fractionating-column

design.

Conical section can be formed on the rolling equipment used to roll cylindrical shells. This is done

by spreading the rolls on one end according to the angle of the cone. The smaller opening of the conical

section must be large enough to accommodate the diameter of the bending roll, which usually is 4, 8, 10

or more inches in diameter.