Fuel Gas Piping and Gas Appliance Connections
Gas Piping Materials and Sizing
Gas piping uses black steel, corrugated stainless steel tubing (CSST), and approved polyethylene for burial. Sizing depends on load, length, and pressure. Questions test pipe sizing tables, the effect of length on capacity, and the prohibition on using certain materials (for example, some plastics) indoors.
Connections and Protection
Joints must be approved: threaded steel, approved CSST fittings, and welded or brazed where allowed. Gas piping must be protected from physical damage, supported, and bonded. Questions test bonding and grounding (CSST requires bonding), protection at penetrations, and the prohibition on running gas piping through certain spaces.
Appliances and Venting
Gas appliances need combustion air, proper venting, and a shutoff valve at the appliance. Questions test the location of shutoff valves, the need for a sediment trap (drip leg), and venting requirements for categories of appliances.
Rule of Thumb
Every gas appliance needs a shutoff valve and, where required, a sediment trap. If a question describes a gas smell, the answer is to shut off the gas, ventilate, and call the utility, not to test with a flame.
Worked Example
A new gas range is installed without a sediment trap. The fix is to add a drip leg at the appliance connection to protect the controls from debris.