Uniform Plumbing Code - Gas Piping and Mechanical Provisions
What this domain covers
This domain tests fuel gas piping and related mechanical provisions: materials, sizing, installation, shutoff valves, sediment traps, appliance connectors, combustion air, venting and pressure testing. Expect scenarios based on a appliance connection or a piping run.
Core rules
- Size gas piping by the appliance Btu input, the longest length of run, the available pressure and the allowable pressure drop, using the UPC gas tables. Do not size by a rule of thumb or by pipe diameter alone.
- Use approved gas piping materials and joints. Protect piping from corrosion and physical damage, support it properly, and keep joints and valves accessible where required.
- Provide a shutoff valve and a sediment trap at each appliance. Appliance connectors must be approved, listed, not concealed, and must not pass through walls, floors or ceilings.
- Provide combustion air and venting for gas appliances. Relief valves and discharge piping must be installed so that discharge is safe and observable.
- Pressure-test gas piping with air or inert gas at the pressure and duration required by the UPC chapter; a common requirement is not less than 10 psi for 15 minutes. Confirm the edition-specific value before the inspection.
Worked example
A 75,000 Btu/h range is connected with a 6-foot flexible connector that passes through a cabinet wall. The connector is concealed and passes through a wall, both violations. The correction is rigid piping to an accessible shutoff valve and sediment trap at the appliance, with an approved connector that is not concealed and does not pass through the wall.
Traps that cost marks
Sizing gas pipe from a rule of thumb; omitting the sediment trap; placing the shutoff valve where it is inaccessible; running a connector through a wall; testing with water instead of air or inert gas; and ignoring combustion air for a confined appliance space.