306A Gas Piping Systems

Question 1

What is the standard test pressure for a residential natural gas piping system in Canada?

Accepted Answer

35 kPa (5 psi) for 15 minutes with no pressure drop

Answer

Residential natural gas piping is typically tested at 35 kPa (5 psi) using air or inert gas for a minimum of 15 minutes with no measurable pressure drop. This is significantly above operating pressure to reveal any leaks.

Question 2

What is the normal operating pressure for natural gas in a residential system?

Accepted Answer

1.75 kPa (7 inches WC)

Answer

Natural gas in residential systems is delivered at approximately 1.75 kPa (7 inches of water column). The gas utility regulates the pressure down to this level at the meter.

Question 3

What method must be used to detect gas leaks in piping?

Accepted Answer

An approved combustible gas detector or soapy water solution applied to joints

Answer

Gas leaks must be detected using an approved combustible gas detector or by applying a soap-and-water solution to joints and connections. Bubbles indicate a leak. Never use an open flame to check for gas leaks.

Question 4

What pipe material is most commonly used for interior residential natural gas piping in Canada?

Accepted Answer

Black steel (iron) pipe

Answer

Black steel (iron) pipe with threaded fittings is the most common material for interior natural gas piping. It is strong, durable, and approved for gas service. Galvanized pipe is not recommended because the zinc coating can flake off and clog gas valve orifices.

Question 5

What is a 'drip leg' (sediment trap) on a gas line and where is it required?

Accepted Answer

A vertical section of pipe with a cap at the bottom, installed at each gas appliance connection to catch moisture and debris before it enters the appliance

Answer

A drip leg (sediment trap) is a short vertical pipe section with a cap, installed at the gas appliance connection point. It catches moisture, dirt, and pipe scale that could damage the appliance gas valve or clog the burner orifices.

Red Seal Plumber 306A Practice Test

Red Seal Plumber 306A Practice Test

306A Gas Piping Systems