b.

Materials and Initial Calculations. Carbon steel, ASTM

Specification A-516 grade 70, a Category 1 plate material, is chosen as the

material from which to fabricate both the chamber and the support cylinder.

From Table ACS-1 of Section VIII, Division 2*, the design stress intensity

value, Sm, is shown as 23,300 psi at 100 deg. F and 23,100 psi at 200 deg.

F. Linearly interpolating sets Sm at 150 deg. F at 23,200 psi. Based on

this, the Stress Intensity Limits for the vessel become (see para. 2.e of

this Section):

Pm < / = 23,200 psi

PL < / = 34,800 psi

Pm (or PL) + Pb < / = 34,800

PL + Pb + Q < / = 69,600 psi

(1) Stress Intensity Range. From Figure 5-110 1, for a life of

10,000 cycles, a permissible Sa = 37,000 psi. Thus, since the pressure

loading is from 0 to 1000 psig, the full allowable stress intensity range is

2Sa = 74,000 psi.

(2) Membrane Stress Intensity Limit. From Table AD-150-1, the

factor to apply to the Membrane Stress Intensity is 1.0.

(3) Minimum Shell Thickness. From paragraph AD-202 of Article

D-2, the minimum shell thickness of the sphere is calculated from:

0.5 PR

tsp =

(for internal pressure loading only)

S - 0.25P

where

tsp =

minimum required thickness of sphere, inches

P

=

design pressure, psi

R

=

inside radius of shell, inches

S

=

factor from Table AD-150-1 times Sm, in this case

1.0 Sm, psi

0.5 PR(1000.0)(90.0)

tsp =

23,200 - 0.25(1000.0)

tsp =

1.98 inches, use 2.0 inches.

(4) Total Dead Weight.

The weight of the seawater in the full

chamber would be approximately:

* Note: Henceforth all references to Tables and Figures made in this

analysis shall be assumed to be those found in Section VIII,

Division 2, unless otherwise noted.

Integrated Publishing, Inc. |