3 Part 2, Section II—Materials and Specifications
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Chapter 3 has multiple authors, and in Chapter 3.1, History of Materials in the ASME Boiler and Pressure Vessel Code, Domenic Canonico traces the chronological evolution of materials and associated technologies, from the need for materials to accommodate riveted construction to the acceptance of fusion welding as a fabrication process. Included in this discussion are the application of advanced materials, the revisions to the basis for setting allowable stress values, and the acceptance of Material Specifications other than those approved by ASTM. Also covered is the evolution of materials, from their humble beginning as a 35-page inclusion in the 1914 Edition of the Boiler Code to the 3994-page, four-Part 2001 Edition of Section II of the ASME B&PV Code. Chapter 3.1 provides some insight not only into the materials needed for the design and fabrication of power boilers but also into the determination of the Maximum Allowable Working Pressure. With the aid of tables, Domenic discusses the Material Specifications from the 1914 through the present Code Editions. Chapter 3.2, authored by Richard Moen and Elmar Upitis, discusses Code Section II, Part A—Ferrous Material Specifications, adopted by ASME for the construction of boiler, pressure vessel, and nuclear power plant components. They note that all materials accepted by the various Code Sections and used for construction within the scope of the Code Sections' rules must be furnished in accordance with the Material Specifications contained in Section II, Parts A, B, or C, or referenced in Appendix A of Part A—except where otherwise provided in the ASME Code Cases or in the applicable Code Section. Discussions in Chapter 3.2 include The Organization of Section II, Part A, Guideline on the Approval of New Materials, Appendices, and Interpretations.
In Chapter 3.3, Dennis W. Rahoi provides the basis of and commentary on Section II, Part B—Nonferrous Material Specifications, adopted by ASME for the construction of boiler, pressure vessel, and nuclear power plant components. He notes that all materials allowed by the various Code Sections and used for construction within the scope of the Code Sections' rules must be furnished in accordance with the Material Specifications contained in Section II, Part B or referenced in Appendix A of Part B—except where otherwise provided in the ASME Code Cases or in the applicable Code Section. Dennis discusses alloy definitions; the organization of Section II, Part B Appendices; the acceptable ASTM Editions; Nonmandatory guidelines; the guideline on the Approval of New Materials; the allowable stresses for alloys; and the basis for material acceptance for Code Construction. Dennis also provides cross-references to weldability; ASME Code Sections I, III, IV, VIII, and IX; and Piping Codes B31.1 and B31.3.
Chapter 3.4, authored by Marvin Carpenter, discusses Section II, Part C—Specification for Welding Rods, Electrodes, and Filler Metals. Welding plays a major role in the fabrication of pressure vessels and related components to the requirements of the ASME B&PV Code. Marvin provides the basis for the Specifications and Standards enveloped by Section II, Part C and their relations to the ANSI∕AWS specifications. Marvin indicates that Section II, Part C does not include all the welding and brazing materials available to the industry—only those Specifications applicable to ASME Code Construction. Discussions also include Code Cases pertinent to this chapter. Chapter 3.4 highlights the major features of the Welding Material Specifications contained in Section II, Part C and the relationship of these Specifications to other Sections of the Code, including Section IX. Included are the electrode classification system, material descriptions, welding material applications, welding material procurement, and filler-metal certification. Chapter 3.4 should prove useful for one to gain a basic understanding of ASME∕AWS Welding Material Classification and Specification.
Chapter 3.5, authored by Richard Moen and Elmar Upitis, covers Section II, Part D—Properties. The coverage includes properties of ferrous and nonferrous materials adopted by the Code for design of B&PV and nuclear power plant components. This coverage includes tables of maximum allowable stresses and design-stress intensities for the materials adopted by the various Code Sections, as well as a discussion of yield strength and tensile strength at various temperatures, external-pressure charts, and other properties for the design of items covered by the various Code Sections. With the aid of several tables, they provide in-depth information about “where is what” in Section II, Part D, and in addition, they note that although much of the information in the various Subparts and Appendices of Section II, Part D was compiled in several places in earlier Code Section Editions, in current editions it is compiled entirely in Section II, Part D to reduce the length of, avoid the duplication of, and facilitate the use of the Code Sections. Thus their commentary can be a useful “road map” even for Users of earlier Code Sections, because it encapsulates—all in one place—information crucial to Designers and Practicing Engineers.