This chapter shall govern the installation, alteration and repair of boilers, water heaters and pressure vessels.
1. Pressure vessels used for unheated water supply.
2. Portable unfired pressure vessels and Interstate Commerce Commission containers.
3. Containers for bulk oxygen and medical gas.
4. Unfired pressure vessels having a volume of 5 cubic feet (0.14 m3) or less operating at pressures not exceeding 250 pounds per square inch (psi) (1724 kPa) and located within occupancies of Groups B, F, H, M, R, S and U.
5. Pressure vessels used in refrigeration systems that are regulated by Chapter 11 of this code.
6. Pressure tanks used in conjunction with coaxial cables, telephone cables, power cables and other similar humidity control systems.7. Any boiler or pressure vessel subject to inspection by federal or state inspectors.
7. Boilers that exceed one of the following (in other than
one- and two-family dwellings and apartment houses
of less than six families) are under the jurisdiction of
the North Carolina Department of Labor in accordance
with General Statute Chapter 95, Article 7A,
7.2. A water temperature of 200°F (93.3°C).
7.3. A nominal water capacity of 120 gallons (454 L).
Every boiler or modular boiler shall have a shutoff valve in the supply and return piping. For multiple boiler or multiple modular boiler installations, each boiler or modular boiler shall have individual shutoff valves in the supply and return piping.
Exception: Shutoff valves are not required in a system having a single low-pressure steam boiler.
Closed-type expansion tanks shall be installed in accordance with the manufacturer’s instructions. The size of the tank shall be based on the capacity of the hot-water-heating system. The minimum size of the tank shall be determined in accordance with the following equation:
Vt = Minimum volume of tanks (gallons) (L).
Vs = Volume of system, not including expansion tanks (gallons) (L).
T = Average operating temperature (°F) (°C).
Pa = Atmospheric pressure (psi) (kPa).
Pf = Fill pressure (psi) (kPa).
Po = Maximum operating pressure (psi) (kPa).