Figure 2-17 shows a detail of the geometric model of the 4.0 inch nozzle

section. This illustration portrays exactly what the computer sees. As can

be noted, by comparing this figure to Figure 2-10, the actual geometry of the

structure was closely followed.

The loadings and boundary conditions applied to model No. 1 are shown in

Figure 2-14. The cylinder representing the support skirt is fixed at its

base. Parts 7 and 12 are loaded only by a meridional membrane force of 1,000

and 1006.6 lb/in. respectively representing the membrane forces in the pipes

leading from the nozzles. These pipe sections were modeled sufficiently long

such that no moment or shear loads are present at their ends. The pressure

acting inside the sphere is uniformly variable and is equal to the 1000 psig

applied pressure plus the pressure head of the water. The dead weight load

of the shell was neglected for two reasons: (1) it is small compared to the

other loads, and (2) it remains a constant factor and thus need not be con-

sidered from ,the viewpoint of fatigue. This latter point is valid as long

as the prior point is valid. Remember, all the load induced stresses must

meet certain static stress limitations prior to meeting the 2 Sa fatigue

stress limitation. Some of the maximum stresses and the location and

direction in which they act are shown in Figures 2-17 and 2-18. Here

[sigma] [PHI] is a meridional stress acting in the plane of the paper, along

the surface of the shell. [sigma][theta] is a circumferential stress acting

perpendicular to the plane of the paper along a circumferential line of the

shell. Membrane stress, whether in the [PHI] or [sigma] direction, is an

average stress assumed to act uniformly through the thickness of the shell.

This is true of course for all the models.

(b) Model No. 2.

This model, as shown in Figure 2-15, is

composed of 13 parts as follows:

Part No.

Type of Shell

Thickness, inches

1

Sphere

2.0

2

Sphere

2.0

3

Sphere

Variable (to model the taper

transition joint and part of

the reinforcement)

4

Torus

Variable (geometrically, a

spherical section and a

cylindrical section)

5

Cylinder

1.0

6

Cylinder

1.0

7

Cylinder

Variable (to model the flange

taper transition)

8

Torus

Variable (geometrically a flat

rectangular ring modeling

part of the flange)

9

Conical

1.5 (rest of flange)

10

Conical

1.5 (same as 9)

11

Torus

(Same as 8)

12

Torus

1.0

13

Torus

1.0

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