Resources for boiler codes and standards
Know the codes, standards, and resources when working on boilers and boiler system design.
Perhaps the most widely accepted boiler and pressure code in the world is the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. This is an internationally recognized standard governing the design and construction of heating and power boilers and unfired pressure vessels. This code—most recently updated in 2013—is organized into 12 sections, including requirements for the nuclear power industry. Those most pertinent to the HVAC industry include:
- Section I—Power Boilers: This section covers power boilers, electric boilers, miniature boilers, heat recovery steam generators, high-temperature water boilers, and certain fired pressure vessels for stationary service, and power boilers for locomotive, portable, and traction service. This standard applies to steam boilers generating steam at more than 15 psi and hot water boilers generating hot water at temperatures over 250 F or pressures higher than 160 psi.
- Section II—Materials: This covers specifications and properties for ferrous and nonferrous materials.
- Section IV—Heating Boilers: A heating boiler is a steam boiler with design pressure less than 15 psi or a hot water boiler with design pressure less than 160 psi and design temperature less than 250 F. This section covers rules for the design and construction of heating boilers.
- Section V—Nondestructive Examination: This section contains radiographic, ultrasonic, and liquid penetrant examination methods required by other code sections, which detect discontinuities in materials, welds, and fabricated parts and components.
- Section VI—Recommended Rules for Care and Operation of Heating Boilers: This has guidelines applicable to steel and cast iron boilers within the operating range for Section IV—Heating Boilers, including associated controls and automatic fuel burning equipment.
- Section VII—Recommended Guidelines for the Care of Power Boilers: This section has guidelines applicable to stationary, portable, and traction type boilers within the operating range for Section I—Power Boilers, to assist operators in maintaining plant safety.
- Section VIII—Pressure Vessels: This section has three divisions, the first covering fired and unfired pressure vessels operating in excess of 15 psig, the second covering alternative rules for the design of pressure vessels by analysis, and the third covering high-pressure vessels.
- Section IX—Welding and Brazing Qualifications: it has rules for qualification of welding and brazing procedures and welders, brazers, and welding and brazing operators for component manufacture.
Other ASME codes that establish standards for boiler system components include the B31 series for piping and the CSD series for controls and safety devices. Sometimes boiler specifications, particularly for large boilers, reference ASME Test Codes with regard to measuring boiler performance. The most common of these in the HVAC and building construction industry are:
- ASME B31.1: Power Piping (2012 edition) covers nonboiler external piping from a boiler operating above 15 psi, including central and district heating piping systems that distribute the steam or hot water to buildings. ASME B31.1 also covers piping within buildings that exceeds the service limits of B31.9.
- ASME B31.9: Building Services Piping (2011 edition) covers piping within the building, including boiler external piping not over 15 psi for steam or 250 F and/or 160 psi that does not exceed the specified service limits. Large and heavy wall pipe is excluded. Steam, condensate, and compressed gases at pressures above 150 psi, liquids above 350 psi, steam and condensate over 366 F, other gases and vapors more than 200 F, and all other liquids more than 250 F are excluded.
- ASME CSD-1: Controls and Safety Devices for Automatically Fired Boilers (2012 edition).
ASME performance test codes also are used to determine efficiency and capacity of boilers and boiler system components, particularly for large, nonresidential equipment.
Code and standards to law
State and municipal building and mechanical codes, and state and municipal boiler and pressure vessel codes adopted through legislative process by states and localities are the vehicles by which a recognized code or standard becomes law. The most widely used and referenced model building, plumbing, and mechanical codes in the United States are currently the International Code Series produced by the International Code Council.
The ASME Boiler and Pressure Vessel Code and the National Board (NB) of Boiler & Pressure Vessel Inspectors Standards form the basis for most state and local occupational safety and health laws relating to boiler and pressure vessel safety. The state laws typically generally adopt the ASME and NB rules, some with state-specific modifications for their application. State laws frequently lag a few years behind the most recent version of the code due to the time it takes for updates to pass through the legislative process.
ASME B31.9 Building Services Piping
ASME also provides standards related to qualifications for authorized inspection of boilers and pressure vessels and also operator qualification.
National Board of Boiler & Pressure Vessel Inspectors (NBBPVI): This organization is composed of chief inspectors for jurisdictions within North America and Mexico and exists to promote uniformity in the design, construction, installation, maintenance, alteration, and repair of pressure containing systems including boilers.
- ANSI/ NBBPVI-23 is a standard that provides rules and guidelines for in-service inspection, repair, and alteration of pressure-retaining items.
- NBBPVI 264 Criteria for Registration of Boilers, Pressure Vessels, and Pressure Retaining Items presents a uniform criteria for a manufacturer's registration of its certification that a given boiler has been manufactured to an acceptable standard.
ASHRAE: This society provides many resources related to the design and performance assessment of boiler systems, including the Handbook Series, ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings, and ASHRAE Standard 118.1 (2012): Electric, and Oil Service Water Heating Equipment.
ASHRAE 90.1 defines minimum efficiency requirements for gas and oil-fired boilers.
ASHRAE 118.1 is applicable to electric resistance, electric air-source heat pump, gas-fired, and oil-fired water-heating equipment, including hot water supply boilers with input ratings less than 12.5 million Btu/h (3660 kW) and greater than:
- Electric resistance 12 kW
- Electric heat pump 6 kW (including all 3 phase regardless of input)
- Gas-fired 75,000 Btu/h (22 kW)
- Oil-fired 105,000 Btu/h (31 kW).