7 Section III: Subsections NC and ND—Class 2 and 3 Components Available to Purchase

This chapter addresses unique features of pressure vessels and atmospheric and 0–15 psi flat bottom storage tanks, as presented in the ASME Boiler and Pressure Vessel Code, Section III, Rules for Construction of Nuclear Power Plant Components, Division 1, Subsections NC (Class 2) and ND (Class 3) Components. Emphasis is directed at discussing the generic design issues of flat bottom tanks. Subsections NC and ND are a combination of rules and requirements taken from Section III, Subsection NB and Section VIII. In addressing the Articles of Subsections NC and ND, the chapter 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. The chapter begins with a discussion on the material selection and qualification requirements as defined in NC-2000 AND ND-2000. It then describes the requirements for fabrication and installation, including forming, cutting, and aligning. In addition, the chapter outlines the requirements for nondestructive examination of NC for vessels and sidewall of tanks. It also discusses the requirements for hydrostatic testing and overpressure and vacuum protection of 0–15 psi tanks and atmospheric tanks. The rules governing nameplates, stamping, and data reports are then presented. Finally, the chapter provides a summary of changes made to the various editions of this Code.