Chapter 7, authored by Thomas J. Ahl for the first Edition, and co-authored by Marcus N. Bressler for the second Edition, provides commentary on Section III, Subsections NC and ND. This commentary addresses pressure atmospheric tanks, and 0–15 psig tanks as presented in the ASME B&PV Code, Section III, Division 1, Subsection NC, Class 2 Components and Subsection ND, Class 3 Components. This chapter does not address piping, pumps, and valves; these are addressed in Chapter 8 for Class 2 and Class 3 Piping, and in Chapter 13 for Nuclear Pumps and Valves. This chapter discusses, in order, each of the eight major Code Articles: Introduction; Materials; Design, Fabrication and Installation; Examination; Testing; Overpressure Protection and Name Plates; and Stamping and Reports. In the 1971 Edition, Subsection NB was fully developed in the evolution of the Nuclear Codes; all other were written by using the outline established for NB. Consequently, many of the basic paragraphs contained in Subsection NB and other reference documents were included verbatim in both Subsections NC and ND, when the subsections were published as separate volumes in the 1974 Edition.

Subsections NC and ND are a combination of rules and requirements taken from Section III, Subsection NB and Section VIII. In Chapter 7, Thomas has referenced all of these Codes and meticulously identified both obvious and subtle differences between Subsection NB, the parent Code, and Subsections NC and ND. Thus, because Thomas addresses the Articles of Subsections NC and ND in this part of the commentary, he presents comparisons, the most probable source of origin of the Code requirements, certain insights as well as contradictions that seem to exist, and the specific source document and some of the underlying theory. He provides cross-references to other Code Sections/Subsections/Paragraphs where applicable. Marcus has taken this work and simplified it where possible, and updated it to the 2007 Edition.