ASME Boiler and Pressure Vessel Code

Since its first issuance in 1914, ASME’s BPVC has pioneered modern standards-development, maintaining a commitment to enhance public safety and technological advancement to meet the needs of a changing world. This “International Historic Mechanical Engineering Landmark” now has been incorporated into the laws of state and local jurisdictions of the United States and nine Canadian provinces. The BPVC is in use in 100 countries around the world, with translations into a number of languages. The boiler and pressure-vessel sections of the BPVC have long been considered essential within such industries as electric power-generation, petrochemical, and transportation, among others.

Since its first issuance in 1914, ASME’s BPVC has pioneered modern standards-development, maintaining a commitment to enhance public safety and technological advancement to meet the needs of a changing world. This “International Historic Mechanical Engineering Landmark” now has been incorporated into the laws of state and local jurisdictions of the United States and nine Canadian provinces. The BPVC is in use in 100 countries around the world, with translations into a number of languages. The boiler and pressure-vessel sections of the BPVC have long been considered essential within such industries as electric power-generation, petrochemical, and transportation, among others.

Part A covers Ferrous Material; Part B covers Nonferrous Material; Part C covers Welding Rods, Electrodes, and Filler Metals; and Part D covers Material Properties in both Customary and Metric units of measure. Together, these four parts of Section II comprise a “service Code” to other BPVC Sections, providing material specifications adequate for safety in the field of pressure equipment. These specifications contain requirements for chemical and mechanical properties, heat treatment, manufacture, heat and product analyses, and methods of testing. Part A and Part B specifications are designated by SA or SB numbers, respectively, and are identical with or similar to those of specifications published by ASTM and other recognized national or international organizations. Part C specifications are designated by SFA numbers and are derived from AWS specifications.

It provides general requirements which address the material, design, fabrication, examination, testing and overpressure protection of the items specified within each respective Subsection, assuring their structural integrity.

SUBSECTION NCA (DIVISIONS 1 & 2)

Subsection NCA, which is referenced by and is an integral part of Division 1 and Division 2 of Section III, covers requirements for quality assurance, certification, and authorized inspection for Class 1, 2, 3, MC, CS and CC construction.

DIVISION 1, SUBSECTIONS NB, NC AND ND

Subsection NB addresses items which are intended to conform to the requirements for Class 1 construction.

Subsection NC addresses items which are intended to conform to the requirements for Class 2 construction.

Subsection ND addresses items which are intended to conform to the requirements for Class 3 construction.

It provides requirements for design, fabrication, installation and inspection of steam heating, hot water heating, hot water supply boilers, and potable water heaters intended for low pressure service that are directly fired by oil, gas, electricity, coal or other solid or liquid fuels. Rules pertaining to use of the single ASME certification mark with the H, HV, and HLW designators are also included.

It is another “service Code” – containing requirements and methods for nondestructive examination which are referenced and required by other BPVC Sections. It also includes manufacturer’s examination responsibilities, duties of authorized inspectors and requirements for qualification of personnel performing inspections and examination. Examination methods are intended to detect surface and internal discontinuities in materials, welds, and fabricated parts and components. A glossary of related terms is included.

It covers operation guidelines applicable to steel and cast-iron boilers limited to the operating ranges of Section IV Heating Boilers. Section VI includes guidelines for associated controls and automatic fuel-burning equipment. Also included is a glossary of terms commonly associated with boilers, controls, and fuel-burning equipment.

It provides guidelines to assist those directly responsible for operating, maintaining, and examining power boilers. These boilers include stationary, portable, and traction type boilers, but not locomotive and high-temperature water boilers, miniature boilers, nuclear power-plant boilers (see Section XI), heating boilers (see Section VI), pressure vessels, or marine boilers. Guidelines are also provided for operation of auxiliary equipment and appliances that affect the safe and reliable operation of power boilers.

Division 1 provides requirements applicable to the design, fabrication, inspection, testing, and certification of pressure vessels operating at either internal or external pressures exceeding 15 psig. Such vessels may be fired or unfired. This pressure may be obtained from an external source or by the application of heat from a direct or indirect source, or any combination thereof. Specific requirements apply to several classes of material used in pressure vessel construction, and also to fabrication methods such as welding, forging and brazing.

Division 1 contains mandatory and non-mandatory appendices detailing supplementary design criteria, nondestructive examination and inspection acceptance standards. Rules pertaining to the use of the single ASME certification mark with the U, UM and UV designators are also included.

Division 2 requirements on materials, design, and nondestructive examination are more rigorous than in Division 1; however, higher design stress intensity values are permitted. These rules may also apply to human occupancy pressure vessels typically in the diving industry. Rules pertaining to the use of the single ASME certification mark with the U2 and UV designators are also included.

Division 3 requirements are applicable to pressure vessels operating at either internal or external pressures generally above 10,000 psi. It does not establish maximum pressure limits for either Section VIII, Divisions 1 or 2, nor minimum pressure limits for this Division. Rules pertaining to the use of the single ASME certification mark with the U3, UV3 and UD3 designator are also included.

It is another “service Code” – containing rules relating to the qualification of welding, brazing, and fusing procedures as required by other BPVC Sections. It also covers rules relating to the qualification and requalification of welders, brazers, and welding and brazing operators in order that they may perform welding or brazing in component manufacture. Welding, brazing and fusing data cover essential and nonessential variables specific to the welding, brazing or fusing process used.

It provides requirements for construction of a fiber-reinforced plastic pressure vessel (FRP) in conformance with a manufacturer’s design report. It includes production, processing, fabrication, inspection and testing methods required for the vessel. Section X includes three Classes of vessel design: Class I and Class III – qualification through the destructive test of a prototype; and Class II – mandatory design rules and acceptance testing by nondestructive methods. These vessels are not permitted to store, handle or process lethal fluids. Vessel fabrication is limited to the following processes: bag-molding, centrifugal casting and filament-winding and contact molding. Rules pertaining to the use of the single ASME certification mark with the RP designator are also included.

It provides rules for the examination, inservice testing and inspection, and repair and replacement of components and systems in light water cooled nuclear power plants. Application of Section XI begins when the requirements of the “construction code” (e.g., Section III) have been satisfied.

Section XI constitutes requirements to maintain the nuclear power plant while in operation and to return the plant to service, following plant outages, and repair or replacement activities. These rules require a mandatory program of scheduled examinations, testing, and inspections to evidence adequate safety. The method of nondestructive examination to be used and flaw size characterization are also contained within this Section.

It provides requirements for construction and continued service of pressure vessels for the transportation of dangerous goods via highway, rail, air or water at pressures from full vacuum to 3,000 psig and volumes greater than 120 gallons. “Construction” is an all-inclusive term comprising materials, design, fabrication, examination, inspection, testing, certification, and over-pressure protection. “Continued service” refers to inspection, testing, repair, alteration, and recertification of a transport tank that has been in service. Rules pertaining to the use of the single ASME certification mark with the T, TD, and TV designators are included.

The BPVC is revised every two years. But what happens in the interim with new materials or alternative constructions? How does the BPVC keep current with the latest in technology and applications? Code Cases are approved actions by the BPVC Committees on these alternatives, intended to allow early and urgent implementation of requirements. They are issued four times per year in two categories: Boiler and Pressure Vessels (CC-BPV) and Nuclear (CC-NUC). Users may purchase individual publications at any time. Or they may subscribe to receive full sets of Code Cases as they are published for the duration of that BPVC edition’s cycle. This responsiveness to requests illustrates the unique openness and transparency of ASME’s code-development process – striving to reflect best-practices of industry, while contributing to safety for the general public.