About this chapter: Chapter 10 addresses boilers, water heaters, expansion tanks and pressure vessels in general, such as compressed air vessels. This chapter includes requirements for components of hydronic HVAC systems, with the focus being on safety, maintenance, testing and safety control devices.
- Pressure vessels used for unheated water supply.
- Portable unfired pressure vessels and Interstate Commerce Commission containers.
- Containers for bulk oxygen and medical gas.
- 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.
- Pressure vessels used in refrigeration systems that are regulated by Chapter 11 of this code.
- Pressure tanks used in conjunction with coaxial cables, telephone cables, power cables and other similar humidity control systems.
- Any boiler or pressure vessel subject to inspection by federal or state inspectors.
|BOILER TYPE||MINIMUM |
FROM TOP OF
except where a greater clearance is required inthis table.
All boilers without manholes on top of the
where a greater clearance is required in thistable.
High-pressure steam boilers with steam generating
capacity not exceeding 5,000 pounds perhour.
High-pressure steam boilers with steam generatingcapacity exceeding 5,000 pounds per hour.
High-pressure steam boilers having heating surfacenot exceeding 1,000 square feet.
High-pressure steam boilers having heating surfacein excess of 1,000 square feet.
High-pressure steam boilers with input notexceeding 5,000,000 Btu/h.
High-pressure steam boilers with input inexcess of 5,000,000 Btu/h.
Steam-heating boilers and hot water-heatingboilers with input exceeding 5,000,000 Btu/h.
Steam-heating boilers exceeding 5,000 poundsof steam per hour.
Steam-heating boilers and hot water-heating
boilers having heating surface exceeding 1,000square feet.
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, 1 pound per hour = 0.4536 kg/h, 1 Btu/hr = 0.293 W.
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.
Safety and relief valve discharge pipes shall be of rigid pipe that is approved for the temperature of the system. High-pressure-steam safety valves shall be vented to the outside of the structure. The discharge piping serving pressure relief valves, temperature relief valves and combinations of such valves shall:
- Not be directly connected to the drainage system.
- Discharge through an air break located in the same room as the appliance.
- Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air break.
- Serve a single relief device and shall not connect to piping serving any other relief device or equipment.
- Discharge to the floor, to the pan serving the boiler or storage tank, to a waste receptor or to the outdoors.
- Discharge in a manner that does not cause personal injury or structural damage.
- Discharge to a termination point that is readily observable by the building occupants.
- Not be trapped.
- Be installed so as to flow by gravity.
- Not terminate more than 6 inches (152 mm) above the floor or waste receptor.
- Not have a threaded connection at the end of such piping.
- Not have valves or tee fittings.
- Be constructed of those materials listed in Section 605.4 of the North Dakota State Plumbing Code or materials tested, rated and approved for such use in accordance with ASME A112.4.1.
An expansion tank shall be installed in every hot water system. For multiple boiler installations, not less than one expansion tank is required. Expansion tanks shall be of the closed or open type. Tanks shall be rated for the pressure of the hot water system.
Exception: Expansion tanks shall not be required in the collector loop of drain-back systems.
Closed-type expansion tanks shall be installed in accordance with the manufacturer's instructions. Expansion tanks for systems designed to have an operating pressure in excess of 30 psi (207 kPa) shall be constructed and certified in accordance with the ASME Boiler and Pressure Vessel Code. 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 where all necessary information is known:
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).
Pƒ = Fill pressure (psi) (kPa).
Po = Maximum operating pressure (psi) (kPa).
Where all necessary information is not known, the minimum size of the tank shall be determined from Table 1009.2.
CLOSED-TYPE EXPANSION TANK SIZING
|SYSTEM VOLUME |
|TANK CAPACITIES IN GALLONS|
For SI: 1 gallon = 3.795 L.