Further, two-thirds of this material must be emplaced at a distance from the
centerline of the 40.0 inch opening equal to 26.73 inches. It was decided to
use a balanced reinforcement (equal thickness of reinforcement on the top and
bottom surface) as shown here in Figure 2-12. This is a forged section. The
1.0 inch wall 40.0 inch inner diameter cylinder is welded to the top of the
forging with a full penetration weld. (See Article D-4 and Figure
AD-610.1(a).) A 2.0 inch radius fillet weld is laid in and ground as shown.
Again the taper transition is equal to 3 times the height of the rise to the
top of the reinforcement surface. As in the case of the viewport reinforcing
ring, this configuration must use some other method than the "Stress Index
Method" for a fatigue evaluation.
(10) Door. The "door" falls into the classification of an
appurtenance and its design should be governed by the criteria described in
Chapter 3, "Appurtenances" of this manual. Its design will generally be
quite complex and may require experimental evaluation to meet the
requirements of Section VIII, Division 2. It must be so evaluated because it
does form a part of the main pressure boundary of the vessel.
However, as
an example of how "design by analysis" may be applied in this case a
torispheroidal or equivalent elliptical head and flange arrangement shall be
designed. The flanges are to be secured by some clamping arrangement. Bolts
could apply for a Class II vessel; some "C" type clamp arrangement could
apply for a Class I vessel. This example shall not go into the method of
hinging or clamping the "door."
o Design of head - the head was chosen to be an
ellipsoidal one where D/2h = 2. Here D is the
inside diameter of the 40.0 inch cylinder and
h is one-half the minor axis of the ellipse.
Thus h = 10.0 inches. Further, this head has an
L/D = 0.90 and a r/D = 0.17, where L is the inside
radius of the spherical portion of the head
and r is the inside radius of the toroidal section.
Thus L = 3.60 inches and r = 6.8 inches.
o To determine the minimum thickness of this head
apply paragraph AD-204.3. This paragraph requires
that tmin is the larger of
KPD
t =
2S
or
PD
t =
2S - P
where t = minimum thickness, inches
P = internal pressure plus a static head, psi
d = inner diameter of major axis, in this case
the inner diameter of the cylinder, inches
S = factor from Table AD-150.1 times Sm, in
this case 1.0 Sm psi
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