inserted nozzle configuration was based on a
desire to minimize machine and welding costs,
and meet the specifications of Paragraph AD-611
and Figure AD-610.1.
8) Viewport Mounting Ring. Assume that the viewport configuration to be
employed is of the type portrayed in Figure 3-6 in Chapter 3,
"Appurtenances." Such a configuration requires a penetration through the
shell. Assume that this penetration must have a 10.0 inch diameter. It is
decided to use a flat plate insert reinforcing ring as shown in Figure 2-11.
The taper transition was established by the requirements of Paragraph AD-420
and Figure AD-420.2, which deal with the joining of two sections with
significant differences in thickness. Basically, the length of the taper
must be at least 3 times the rise, on each surface, from one shell part to
its adjoining part. Such a reinforcement does meet the area replacement
specifications.* It does not meet the specifications of Article 4-6 and
thus must be evaluated for fatigue by some method other than the "Stress
Index Method."
(9) Entranceway-shell Intersection. The minimum thickness of the
cylindrical portion of the entranceway is established from Paragraph AD-201
by:
PR
tmin =
S - 0.5P
where all terms are described in Paragraph 7.b.(3) preceding.
Thus
(1000)(20.0)
tmin = =0.88 inches
23,200 - 0.5(1000)
use t = 1.00 inch.
The designer is now confronted with the intersection of a minimum thickness
main shell and a basically minimum thickness cylinder. Thus, reinforcing
material must be added to compensate for the opening. The area of
reinforcing material to be emplaced on a plane on each side of the opening is
Ar = 0.5(40.0)(2.0) = 4.0 in2
* NOTE:
At this time Section VIII, Division 2, sets the limit on height
of reinforcement only for those types of nozzles and other
reinforcements detailed specifically in Figures AD-540.1 and
AD-612.1. This is being changed. In the meantime, use Section
VIII, Division 1, para. UG-40(c). (Basically, 2.5 times the
nominal wall thickness of the vessel normal to each surface.)
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