Gas Piping, Tubing and System Installation
Gas Piping, Tubing and System Installation tests materials, sizing, routing, protection, and pressure testing. The exam expects you to read a simple system, choose an approved material, size the line for the load, and install it so it can be tested, purged, and serviced.
Materials and fittings
- Approved materials include Schedule 40 black steel pipe, wrought-iron pipe, CSA-certified CSST, and copper tubing where the code and local utility permit it. Propane systems commonly use copper; many Ontario natural gas utilities restrict or prohibit it.
- Use malleable iron or forged steel fittings. Dielectric unions prevent galvanic corrosion. Never use cast iron, aluminum, or plastic fittings indoors unless specifically listed.
- Join steel pipe with approved thread compound or tape applied to male threads only, leaving the first two threads bare. Do not put compound on flare faces.
- CSST must be listed, installed with the manufacturer's strike plates and sleeves, and bonded to the electrical grounding system with a conductor sized per the Canadian Electrical Code.
Sizing and layout
Use the longest-run method: measure from the meter to the farthest appliance, add equivalent length for fittings and valves, and apply the code's allowable pressure drop (commonly 0.5 in. w.c. for low-pressure natural gas). Size each section for the connected load downstream. Provide a shutoff valve, union, and sediment trap (drip leg) at each appliance; slope horizontal piping to the trap and support it at code intervals.
Worked example
A 1/2-in. steel branch with an equivalent length of 30 ft has a table capacity of 65,000 Btu/h at 0.5 in. w.c. drop. It serves a 45,000 Btu/h range and a 35,000 Btu/h water heater, total 80,000 Btu/h. Because 80,000 > 65,000, the branch is undersized; increase to 3/4-in. or reduce the load. Recheck the table after adding fittings.
Traps
- Sizing on developed length only and ignoring fittings.
- Forgetting the sediment trap or installing it in the wrong direction.
- Using thread compound on flare seats.
- Concealing a union or valve where it cannot be accessed.
- Bonding CSST to a water line instead of the electrical grounding electrode.