ASME BPVC 2023 Section II part D (metric)

NONMANDATORY APPENDIX A
ISSUES ASSOCIATED WITH MATERIALS USED IN ASME CODE
CONSTRUCTION
A-100 GENERAL
The performance over time of the various ferrous and
nonferrous alloys permitted for use in Code construction
may be influenced by many factors, ranging from the processes
involved in their fabrication into components and
their installation to changes in the material structure or
direct damage to the material related to operation in
the intended service. If Code-constructed equipment is
to provide the reasonably long period of safe operation
expected by the users of that equipment, then the equipment
designers must be aware of any potential change in
the materials properties related to fabrication, installation,
or service as they go about selecting materials for
Code usage. Although the Code does not mandate that
all of the various metallurgical phenomena and environmental
effects that can influence material performance
be considered in the design of a Code component, such
consideration is a part of the good engineering judgment
that is expected to be exercised in all Code-related matters
and, as such, this Nonmandatory Appendix is provided
to designers and other Code users to assist in the
material selection process.
Historically, some of the information contained in this
Nonmandatory Appendix has been available in other Sections
of the Boiler and Pressure Vessel Code, as well as in
the Piping Code. In addition to information provided previously
in Nonmandatory Appendix A, Metallurgical Phenomena,
in Section II, Part D, there was information
available in Section VIII and more recently in Section III
Appendices, Nonmandatory Appendix W, Environmental
Effects. A review of these various information sources revealed
that there were many important issues not covered,
and that there were other issues that required
revision to incorporate new information. Thus, what follows
is an expanded coverage of metallurgical phenomena
and environmental effects. It is emphasized,
however, that this is not a comprehensive coverage of
all possible mechanisms, nor is it an exhaustive treatment
of the individual topics. Rather, this revised Appendix is
intended to serve as a more convenient resource for designers
and users of Code equipment as they consider
the many issues that could adversely affect materials in
Code service.
A-110 ISSUES COVERED
Issues covered in this Nonmandatory Appendix include
those listed below it is recognized, of course, that some
of these issues could be placed in more than one of the