Piping serving as part of a heating or cooling system shall be thermally insulated in accordance with Table C403.11.3.
Exceptions:
- Factory-installed piping within HVAC equipment tested and rated in accordance with a test procedure referenced by this code.
- Factory-installed piping within room fan-coils and unit ventilators tested and rated according to AHRI 440 (except that the sampling and variation provisions of Section 6.5 shall not apply) and AHRI 840, respectively.
- Piping that conveys fluids that have a design operating temperature range between 60°F (15°C) and 105°F (41°C).
- Piping that conveys fluids that have not been heated or cooled through the use of fossil fuels or electric power.
- Strainers, control valves, and balancing valves associated with piping 1 inch (25 mm) or less in diameter.
- Direct buried piping that conveys fluids at or below 60°F (15°C).
MINIMUM PIPE INSULATION THICKNESS (in inches)a, c
| FLUID OPERATING TEMPERATURE RANGE AND USAGE (°F) | INSULATION CONDUCTIVITY | NOMINAL PIPE OR TUBE SIZE (inches) | |||||
| Conductivity Btu • in./(h • ft2• °F)b | Mean Rating Temperature, °F | < 1 | 1 to < 1 1/2 | 1 1/2 to < 4 | 4 to < 8 | ≥ 8 | |
| > 350 | 0.32 – 0.34 | 250 | 4.5 | 5.0 | 5.0 | 5.0 | 5.0 |
| 251 – 350 | 0.29 – 0.32 | 200 | 3.0 | 4.0 | 4.5 | 4.5 | 4.5 |
| 201 – 250 | 0.27 – 0.30 | 150 | 2.5 | 2.5 | 2.5 | 3.0 | 3.0 |
| 141 – 200 | 0.25 – 0.29 | 125 | 1.5 | 1.5 | 2.0 | 2.0 | 2.0 |
| 105 – 140 | 0.21 – 0.28 | 100 | 1.0 | 1.0 | 1.5 | 1.5 | 1.5 |
| 40 – 60 | 0.21 – 0.27 | 75 | 0.5 | 0.5 | 1.0 | 1.0 | 1.0 |
| < 40 | 0.20 – 0.26 | 50 | 0.5 | 1.0 | 1.0 | 1.0 | 1.5 |
For SI: 1 inch = 25.4 mm, °C = [(°F) - 32]/1.8.
- For piping smaller than 11/2 inches and located in partitions within conditioned spaces, reduction of these thicknesses by 1 inch shall be permitted (before thickness adjustment required in footnote b) but not to a thickness less than 1 inch.
For insulation outside the stated conductivity range, the minimum thickness (T) shall be determined as follows:
where:
T = minimum insulation thickness,
r = actual outside radius of pipe,
t = insulation thickness listed in the table for applicable fluid temperature and pipe size,
K = conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature (Btu • in/h • ft2 • °F) and
k = the upper value of the conductivity range listed in the table for the applicable fluid temperature.
- For direct-buried heating and hot water system piping, reduction of these thicknesses by 11/2 inches (38 mm) shall be permitted (before thickness adjustment required in footnote b but not to thicknesses less than 1 inch.
Piping insulation exposed to the weather shall be protected from damage, including that caused by sunlight, moisture, equipment maintenance and wind, and shall provide shielding from solar radiation that can cause degradation of the material. Adhesive tape shall not be permitted.