What is the minimum gas piping size for concealed installations?

What is the minimum gas piping size for concealed installations?

• A. 1/2 inch
• B. 1/4 inch
• C. 3/4 inch
• D. 1 inch

Answer: (A)

Gas piping must be large enough to supply the expected gas flow without excessive pressure drop, and for concealed runs the code sets a practical lower limit. The minimum size allowed for piping routed inside walls, ceilings, or other concealed spaces is 1/2 inch. This size provides enough capacity for typical residential loads and helps ensure that multiple appliances can operate simultaneously without starving the supply. The actual pipe size should still be determined by the total gas demand (BTU input), the length of the run, and the allowable pressure drop, using the code’s sizing tables. If a run or appliances require more flow, upsizing is permitted, but you can’t go smaller than 1/2 inch for concealed installations. Smaller than this is not allowed, while larger sizes are acceptable as dictated by the load.

Gas piping must be large enough to supply the expected gas flow without excessive pressure drop, and for concealed runs the code sets a practical lower limit. The minimum size allowed for piping routed inside walls, ceilings, or other concealed spaces is 1/2 inch. This size provides enough capacity for typical residential loads and helps ensure that multiple appliances can operate simultaneously without starving the supply.

The actual pipe size should still be determined by the total gas demand (BTU input), the length of the run, and the allowable pressure drop, using the code’s sizing tables. If a run or appliances require more flow, upsizing is permitted, but you can’t go smaller than 1/2 inch for concealed installations. Smaller than this is not allowed, while larger sizes are acceptable as dictated by the load.