Conical Heads

Internal-pressure design rules and formulas are given for cylindrical and spherical shells and for ellipsoidal, torispherical (often called ASME heads), hemispherical, and conical heads. The formulas given assume membrane-stress failure, although the rules for heads include consideration for buckling failure in the transition area from cylinder to head (knuckle area). 

External-pressure failure of shells can result from overstress at one extreme or n om elastic instability at the other or at some intermediate loading. The code provides the solution for most shells by using a number of charts. One chart is used for cylinders where the shell diameter-to-thickness ratio and the length-to-diameter ratio are the variables. The rest of the charts depic t curves relating the geometry of cyhnders and spheres to allowable stress by cui ves which are determined from the modulus of elasticity, tangent modulus, and yield strength at temperatures for various materials or classes of materials. The text of this subsection explains how the allowable stress is determined from the charts for cylinders, spheres, and hemispherical, ellipsoidal, torispherical, and conical heads. 

Cone-bottom vertical vessels are sometimes used where solids are anticipated to be a problem. Most cones have either a 90 apex (a = 45 ) or a 60 apex ia = 30 ). These are referred to respectively as a 45 or 60 cone because of the angle each makes with the horizontal. Equation 12-4 is for the thickness of a conical head that contains pressure. Some operators use internal cones within vertical vessels with standard ellipsoidal heads as shown in Figure 12-2. The ellipsoidal heads contain the pressure, and thus the internal cone can be made of very thin steel. 

The weight of nozzles and internals can be estimated at 5 to 10% of the sum of the shell and head weights. The weight of a skirt can be estimated as the same weight per foot as the shell with a length given by Equation 12-8 for an ellipsoidal head and Equation 12-9 for a conical head. 

Determine the weight for the following free-water knockout. It is butt weld fabricated with spot x-ray and to be built to Division 1. A conical head (bottom of the vessel) is desired for ease in sand removal. Compare this weight to that of a vessel without the conical section and that to ti ves.sel with a 4-m. plate internal cone. 

An artillery projectile may be either solid or hollow. Hollow projectiles may be filled with explosive or inert material, depending on the type. Artillery projectiles, although differing in characteristic details, are of the same general shape in that they have a cylindrical body and generally an ogival or conical head (or windshield). 

Each branch terminates in an inflorescence which is a dense capitulum of florets (individual tubular corollas), commonly called a flower. Each floret flower protrudes from a conical head surrounded by layers of bracts. The leaves, which develop along the stalk and branches, and the outer layers of bracts usually are spiny, although the types of safflower grown for the production of dye or food coloring are spineless, or nearly so. The seeds of the safflower plant develop within the head in a concentric pattern and are oblate with a flattened top, usually white, and about the size of a barley kernel (Figure 1) (20). 

Conical heads, UHT-19 Internal pres.. UG-32, UHT-32. Appx I -4.5 External pres.. UG-33. UHT-33, Appx L-6... 

Conical Head Head formed in the shape of a cone. 

Machine screws are generally used with threaded inserts, nuts, and clips. They rarely are used in pretapped holes. Particular attention should be paid to the head of the fastener. Conical heads produce undesirable tensile stresses and should not be used. Bolt or screw heads with a flat underside, such as pan heads, round heads, and so forth (Fig. 7.7), are preferred, because the stress produced is more compressive. 

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