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Earlier editions: 20222019

Chapter 10 — BOILERS AND PRESSURE VESSELS

1001.1 Applicability. The requirements of this chapter

California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

shall apply to the construction, installation, operation, repair, and alteration of boilers and pressure vessels. Low-pressure boilers shall comply with this chapter and Section 904.0.

Exceptions:

(1) Listed and approved potable water heaters with a nominal capacity not exceeding 120 gallons (454 L) and having a heat input not exceeding 200 000 British thermal units per hour (Btu/h) (58.6 kW) used for hot water supply at a pressure not exceeding 160 pounds-force per square inch (psi) (1103 kPa) and at temperatures not exceeding 210°F (99°C), in accordance with the plumbing code.

(2) Pressure vessels used for unheated water supply, including those containing air that serves as a cushion and is compressed by the introduction of water and tanks connected to sprinkler systems.

(3) Portable unfired pressure vessels and Interstate Commerce Commission (I.C.C.) containers.

(4) Containers for liquefied petroleum gases, bulk oxygen, and medical gas that are regulated by the fire code.

(5) Unfired pressure vessels in business, factory, hazardous, mercantile, residential, storage, and utility occupancies having a volume not exceeding 5 cubic feet (0.14 m [3] ) and operating at pressures not exceeding 250 psi (1724 kPa).

(6) Pressure vessels used in refrigeration systems shall comply with Chapter 11.

(7) Pressure tanks used in conjunction with coaxial cables, telephone cables, power cables, and other similar humidity control systems.

(8) A boiler or pressure vessel subject to regular inspection by federal inspectors or licensed by federal authorities.

(9) Pressure vessels used in specific appliances shall comply with Chapter 9.

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▸Contents — California Mechanical Code (Title 24, Part 4)
California Mechanical Code (Title 24, Part 4)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — VENTILATION AIR
  5. Chapter 5 — EXHAUST SYSTEMS
  6. Chapter 6 — DUCT SYSTEMS
  7. Chapter 7 — COMBUSTION AIR
  8. Chapter 8 — CHIMNEYS AND VENTS
  9. Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
  10. ▸Chapter 10 — BOILERS AND PRESSURE VESSELS
    Overview
    1. 1001.1 Applicability. The requirements of this chapter
    2. 1001.2 Boiler Rooms and Enclosures. Boiler rooms and
    3. 1001.3 Air for Combustion and Ventilation. Air for
    4. 1001.4 Drainage. For heating or hot-water-supply boiler
    5. 1001.5 Mounting. Equipment shall be set or mounted on a
    6. 1001.6 Chimneys or Vents. Boilers shall be connected to
    7. 1002.1 General. Pressure vessels shall be constructed and
    8. 1002.2 Oil-Burning Boilers. Oil-burning boilers shall
    9. 1002.3 Electric Boilers. Electric boilers shall be listed and
    10. 1002.4 Solid-Fuel-Fired Boilers. Solid-fuel-fired boilers shal…
    11. 1002.5 Dual Purpose Water Heaters. Water heaters utilized for …
    12. 1003.1 Safety Requirements. The construction of boilers and pr…
    13. 1003.2 Controls. Required electrical, mechanical, safety,
    14. 1003.3 Gauges. Steam boilers shall be provided with a
    15. 1003.4 Stack Dampers. Stack dampers on boilers fired
    16. 1003.5 Welding. Welding on pressure vessels shall be done
    17. 1004.1 General. An expansion tank shall be installed in a
    18. 1004.2 Open-Type Expansion Tanks. Open type expansion tanks sh…
    19. 1004.3 Closed-Type Systems. Closed-type systems shall
    20. 1004.4 Minimum Capacity of Closed-Type Tank. The
    21. 1005.1 General. Pressurized vessels or boilers shall be provid…
    22. 1005.2 Discharge Piping. The discharge piping serving a
    23. 1005.3 Splash Shield. Where the operating temperature
    24. 1005.4 Hazardous Discharge. Where the discharge from
    25. 1005.5 Vacuum Relief Valve. Hot-water heating systems
    26. 1006.1 General. An approved manual shutoff valve shall
    27. 1007.1 General. An approved gas-pressure regulator shall
    28. 1008.1 General. Hot water boilers and steam boilers shall
    29. 1009.1 General. The following requirements shall be
    30. 1010.1 General. Where boilers are installed or replaced,
    31. 1010.2 Power Boilers. Power boilers having a steam-generating …
    32. 1010.3 Steam-Heating Boilers, Hot Water Boilers, and
    33. 1010.4 Package Boilers, Steam-Heating Boilers, and
    34. 1011.1 General. The design, installation, and operation of
    35. 1012.1 General. Hot water boiler installations, upon completio…
    36. 1013.1 General. An installation for which a permit is
    37. 1013.2 Operating Permit. It shall be unlawful to operate a
    38. 1013.3 Maintenance Inspection. The Authority Having
    39. 1013.4 Power and Miniature Boilers. Power boilers and
    40. 1013.5 Steam-Heating and Water-Heating Boilers.
    41. 1013.6 Automatic Steam-Heating Boilers. Automatic
    42. 1013.7 Unfired Pressure Vessels. Unfired pressure vessels
    43. 1014.1 General. Boilers and pressure vessels shall be operated…
  11. Chapter 11 — REFRIGERATION
  12. Chapter 12 — HYDRONICS
  13. Chapter 13 — FUEL GAS PIPING
  14. Chapter 14 — PROCESS PIPING
  15. Chapter 15 — SOLAR ENERGY SYSTEMS
  16. Chapter 16 — STATIONARY POWER PLANTS
  17. Chapter 17 — GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE…
  18. Chapter 18 — REFERENCED STANDARDS
  19. Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
  20. Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
  21. Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
  22. Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
  23. Appendix E — SUSTAINABLE PRACTICES
  24. Appendix F — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
  25. Appendix G — EXAMPLE CALCULATION OF OUTDOOR AIR RATE
  26. Appendix H — PROFESSIONAL QUALIFICATIONS
  27. Appendix I — INDOOR HORTICULTURAL FACILITIES
  28. Appendix J — CLEAN AIR DELIVERY

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