Article D-5, "Openings and Their Reinforcement." This article
presents information, which, if used fully and rigorously, will insure a
satisfactory design of penetrations when the vessel is subject to a pressure
load only. Adherence to the rules presented in this article apply to all
"isolated" penetrations and do not apply, except in the most general sense,
to openings or penetrations that are so closely spaced as to be considered
"multiple" openings. "Multiple" openings are to be understood as two or more
openings, which, when considered individually, cause stress fields which
significantly over-lap the area or vicinity of the adjacent openings.
Further, compliance with the specifications of this article, though required,
components nor do these specifications deal with external piping loads. Both
of these factors must be considered carefully by the design engineer.
The designer is urged to read and understand this article completely.
Particular attention should be paid to paragraphs AD-520, -530, -540, and
-550. These paragraphs deal with the establishment of required additional
reinforcing materials and the geometric limits of their application.
Paragraph AD- 560 deals with requirements for nozzles with separate
reinforcing plates (pads, etc.). Though Code-allowable with severe
limitations, the designer is urged to not use such configurations for
pressure vessels for hyperbaric facilities.
Article D-6, "Nozzles and Other Connections." Here, as in article
D-5, rules are presented that deal with acceptable nozzle configurations.
The designer will note, as before, that heavy emphasis is placed on full
penetration and butt weld joints.
For most Code-approved vessels, partial
penetration welds for nonload carrying pipe connections are allowed.
This practice is not recommended for pressure vessels
for hyperbaric facilities. Paragraph AD-640, "Threaded
Connections," gives design data concerning the use of
threaded connections in the main pressure wall of the
vessel. The designer is cautioned to consider the
effects of corrosion, fatigue, and possible leakage
when applying these specifications to hyperbaric vessels.
Article D-7, "Flat Heads, Bolted and Studded Connections." This
article gives guidance in the select on of the initial design thicknesses for
flat head sections and makes specific recommendations as to their connections
to the main body of the vessel. It further makes recommendations and sets
limitations for bolted flange connections. The provisions of paragraph
AD-710 should be used in conjunction with the provisions of Appendix 3,
"Rules for Bolted Connections," of the Code.
Article D-8, "Quick-Actuating Closures." This is a very short
article mainly dealing with the prevention of unintentional opening or
operation of the device. The data detailed in this article provides
guidance in the design of devices described in pertinent paragraphs of
Chapter 3 "Appurtenances" of this manual.