i.
Article D-9, "Attachments and Supports." This article provides
rules and recommendations as to the means of securing attachments and
supports to the main vessel. As before, partial-penetration welds and fillet
welds are permitted in certain applications. Again the designer is cautioned
concerning the use of such weld configurations; particular note should be
taken of paragraph AD-940, "Design of Supports."
j.
Article D-10, "Access and Inspection Openings."
Paragraph
AD-1000, General Requirements," states that
"All pressure vessels for use with compressed air, and those subject to
internal corrosion or having parts subject to erosion or mechanical
abrasion . . . shall be provided with suitable manhole, handhole, or
other inspection openings for examination and cleaning."
The content of this paragraph certainly applies to hyperbaric vessels. In
most cases, however, the need for such manways, etc., will be obviated by the
presence of the doors or hatches incorporated into such vessels. Where there
are specific areas in portions of multi-chambered vessels where interior
inspection may pose a problem, the designer is required to supply such
inspection ports.
4.
APPENDIX 3, "RULES FOR BOLTED FLANGE CONNECTIONS." The first three
articles in this appendix present rules and methods of designing bolted
flange connections of specific types and geometries. The methods, both of
design and analysis, are described in some detail and for the flanges
described the designer may follow these articles as presented. He should
bear in mind however, that, (1) some of the gasket materials and geometries
may not be compatible with the liquid or gaseous media to be employed in the
vessel, and (2) he must still justify his design from the viewpoint of
fatigue.
5.
APPENDIX 6, "EXPERIMENTAL STRESS ANALYSIS." It is within the intent
and specifications of Section VIII, Division 2 that the stress condition
throughout the vessel, while under load, be known. Mathematical analysis can
be carried only so far. It is true that great strides have been made in the
development of mathematical stress analysis techniques in recent years and
that this development of analytic procedures is progressing at an increasing
rate. There remain, however, areas in a complicated pressure vessel for
which no mathematical stress analysis technique is available. For such
areas, the designer may choose to prove his design upon either a model or, if
he has sufficient confidence in his past experience, on the finished pressure
vessel itself. Appendix 6 discusses briefly two basic methods of
experimental stress analysis, (1) use of strain gages, and (2) use of
photoelastic techniques. There are of course many other experimental
techniques that may be employed. References 16 through 23 deal with the
broad field of experimental stress analysis, and the designer may find the
method he chooses to employ described in them. One method of experimental
analysis, combining two techniques, is described briefly below. This method,
when used properly, develops accurate data in an economical manner.
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