Chapter IV of the Code, Standards for Piping Components, tabulates the listed standards. Listed piping components are those that are in accordance with the standards listed in Table 326.1. Metallic pipe and tube listed in Appendix A are also considered to be listed components; they are included by note 5 in the table. Components that do not comply with those standards are considered to be unlisted components. Note that listed components for Chapter VII (nonmetallic) are listed in Table A326.1, metallic components for Chapter VIII (Category M) are listed in Table 326.1, nonmetallic components for Chapter VIII are listed in Table A326.1 and components for Chapter IX (high pressure) are listed in Table K326.1.
Listed components are manufactured in accordance with standards that have been reviewed and accepted by the code committee for use in ASME B31.3 piping systems. The requirements for piping systems in ASME B31.3 do not apply to listed components, unless specifically stated in the Code. As stated in paragraph 326.3, “The design, materials, fabrication, assembly, examination, inspection, and testing requirements of this Code are not applicable to components manufactured in accordance with the documents listed in Table 326.1, unless specifically stated in this Code, or the listed document.” #Little_PEng