This chapter provides criteria and commentary for ASME Section VI, which presents guidelines for the safe and efficient operation of steam-heating boilers, hot-water-supply boilers, and hot-water-heating boilers after installation. These rules are nonmandatory unless they are adopted into the laws of a governmental jurisdiction. The chapter is divided into nine parts, along with the necessary figures and tables for each part. Part 1 covers the scope of the chapter, provides some background on the use of illustrations and manufacturer’s information, and includes a glossary of terms applicable to boilers, fuels, fuel-burning equipment, combustion, and water treatment. Part 2 deals with the classification of boilers based on their design, construction, and application. Different types of boilers, such as steel, cast iron, modular, and vacuum boilers, are described and illustrated. The requirements of accessories such as safety relief valves and pressure gages, and their installation are addressed in Part 3. Part 4 deals with the characteristics of common fuels used for combustion in boilers such as gas, oil, coal, and wood products. Part 5 provides information on the controls for managing the functions of the fuel-burning equipment, namely operating, limit, safety, and programming controls. Part 6 covers all the requirements of boiler-room facilities for safe operation and maintenance. Recommendations for the operation, maintenance, and repair of steam boilers are included in Part 7 in addition to the procedures for inspection of steam boilers. Part 8 deals with the operation, maintenance, and repair guidelines for hot-water boilers and tests and inspections of hot-water-supply and hot-water-heating boilers. Water treatment considerations, boiler water problems, the chemicals used for water treatment and their functions, treatment alternatives, and various procedures are discussed in Part 9.

This chapter presents the rules of the ASME Boiler and Pressure Vessels Code, Section IV, constituting the minimum requirements for the safe design, construction, installation, and inspection of low-pressure steam boilers and hot-water Boilers (which are directly fired with oil, gas, electricity, or other solid or liquid fuels). It is divided into five parts and two sub-parts including several appendices. Part HG addresses the material requirements, design, pressure-relieving devices, tests, inspection, stamping, instruments, fittings and controls, and the installation of low-pressure steam-heating boilers, hot-water-heating boilers, hot-water-supply boilers, and the boilers’ appurtenances. Part HF, dealing with requirements for heating boilers constructed of wrought materials, has two sub-parts: HW and HB. The requirements of HW are applicable to heating boilers and their parts fabricated by welding. HB addresses the requirements for steam-heating boilers, hot-water-heating boilers, hot-water-supply boilers, and the boilers’ fabrication by brazing. The requirements of Part HC apply to steam-heating boilers, hot water-heating boilers, and hot-water-supply boilers and their parts, which are fabricated primarily of cast iron. The requirements of Part HA apply to hot water boilers constructed primarily of cast aluminum. Part HLW addresses the requirements for water heaters in commercial or industrial settings for supplying potable water at pressures not exceeding 160 psig (1100 kPa) and temperatures not exceeding 210°F (99°C). For each part, general requirements, material specifications, design parameters and calculations, fabrication requirements, and information on testing, inspection, and stamping are given. Appendices contained in this chapter include methods of checking safety valve and safety relief valve capacity; examples of methods of calculating a welded ring reinforced furnace; examples of methods of computation of openings in boiler shells; glossary; and two examples of manufacturer’s data report forms.

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First generation nuclear power plants were built onsite with large construction forces over a number of years using a design that was being revised during construction. Vendor supplied equipment skids were the closest thing to modular building techniques at that time. Modularization techniques are available today as a tool for performing parallel construction activities such as fabrication and assembly of components offsite to support the construction cost and schedule goals of a project. Accordingly, extensive planning and coordination is required by engineering, procurement, fabricators, and construction to support modularization. The importance of developing a strategy for the utilization of modularization to the Nuclear Industry, Owners, and Engineering Procurement and Construction (EPC) entities, cannot be over emphasized, ensuring the development of a Corporate Modularization Fabrication Strategy, which incorporates and addresses the following, various elements: • Project Modularization Plan • Definitions and terms for module, modularization, and on-off-site fabrication • Module types • Modularization boundaries • Work processes for interface between Engineering, Procurement, Fabricator, and Quality to allow good communication between entities • Constructability reviews • Modularization schedule linked to integrated project schedule • Compliance with approved procedures and Quality Program requirements • Commitment from management This paper and presentation will discuss and highlight the following for a typical Advanced Boiling Water Reactor (ABWR) application: • Typical Corporate Modularization Fabrication Strategy; • Typical Modularization Concepts; • Modularization: Friend or Foe.

Integral light-water reactor designs propose the use of steam generators located within the reactor vessel. Steam generator tubes in these designs must withstand external pressure loadings to prevent buckling, which is affected by material strength, fabrication techniques, chemical environment and tube geometry. Experience with fired tube boilers has shown that buckling in boiler tubes is greatly alleviated by controlling ovality in bends when the tubes are fabricated. Light water reactor steam generator pressures will not cause a buckling problem in steam generators with reasonable fabrication limits on tube ovality and wall thinning. Utilizing existing Code rules, there is a significant design margin, even for the maximum differential pressure case. With reasonable bend design and fabrication limits the helical steam generator thermodynamic advantages can be realized without a buckling concern. This paper describes a theoretical methodology for determining allowable external pressure for steam generator tubes subject to tube ovality based on ASME Section III Code Case N-759-2 rules. A parametric study of the results of this methodology applied to an elliptical cross section with varying wall thicknesses, tube diameters, and ovality values is also presented.