To be conservative let T = 4.0 inches. The details of the hatch geometry are
shown in Figure 2-23. Note the use of a fillet radius equal to one-half the
cap wall thickness at the intersection of the cap and the compression ring.
Figure 2-23 also shows the details of the tori-spherical end caps.
(8) Supports. The supports are to be saddles. Saddles are not
bodies of revolution and their design is rather involved. The only guidance
that Section VIII, Division 2 gives is found in Article D-9, "Attachments and
Supports," Paragraph AD-940, "Design of Supports" is very general.
Subparagraph (d) of this paragraph does set one limit requiring that
"Horizontal vessels supported by saddles shall use saddles such that they
afford bearing to extend over at least 1/3 of the shell circumference." A
good treatment of the design and analysis of saddle supports is given by Zick
(see Reference 26, Zick, Stresses in Large Horizontal Cylindrical Pressure
Vessels on Two Saddle Supports, 1951). Because of the complexity of the
design analysis of saddles supports, no details of design or analysis for the
supports will be given here. However, the saddles are shown schematically in
Figures 2-24, 2-25, and 2-26. These saddles are built up from 1.0 inch thick
plate sections as shown.
(9) Viewport Penetrations in Cylinder Wall. The viewport
penetrations in the cylinder wall are designed in the same manner that was
applied to the viewport penetrations in the head and the spherical chamber.
The details of these penetrations are shown in Figure 2-27. Note the
variation in taper transition zones as r goes from zero to 90 degrees.
c. Stress Analysis. As before, the above procedure forms the first
phase of a design by analysis. Again note that the vessel has been designed
to be "smooth."
(1) Loading Conditions.
The only loading condition considered was
an internal pressure of 1000 psig.
(2) Requirement for a Fatigue Evaluation. As before, all parts of
Condition A or all parts of Condition B of paragraph AD-160.2 are not met and
a fatigue evaluation is required.
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