306A Gas Piping Systems 2

Question 1

What compound or sealant is approved for use on threaded gas pipe joints?

Accepted Answer

Pipe joint compound or Teflon tape specifically rated for gas service

Answer

Only pipe joint compound or Teflon tape specifically rated and labelled for gas service may be used on gas pipe threads. Gas-rated Teflon tape is typically yellow and thicker than standard white tape used for water connections.

Question 2

Why is corrugated stainless steel tubing (CSST) sometimes preferred over black steel pipe for gas installations?

Accepted Answer

It is flexible, faster to install, and requires fewer joints, reducing potential leak points

Answer

CSST is flexible, allowing it to be routed through walls and floors with fewer joints than rigid steel pipe. Fewer joints means fewer potential leak points. It also installs much faster, reducing labour costs.

Question 3

What special requirement applies to CSST gas tubing regarding electrical grounding?

Accepted Answer

CSST must be bonded to the building's electrical grounding system to protect against lightning-induced damage

Answer

CSST must be electrically bonded to the building's grounding electrode system to protect against damage from lightning strikes. Without bonding, a nearby lightning strike can induce current in the CSST, potentially burning a hole in the thin tubing and causing a gas leak.

Question 4

What is the purpose of a gas shut-off valve at each appliance?

Accepted Answer

To allow the gas supply to be individually isolated for each appliance for maintenance, repair, or emergency

Answer

An individual shut-off valve at each gas appliance allows that appliance's gas supply to be isolated without affecting other appliances in the building. This is essential for safe maintenance, repair, or replacement of individual appliances.

Question 5

What is the maximum allowable pressure drop in a residential gas piping system from the meter to the most remote appliance?

Accepted Answer

0.25 kPa (1 inch WC)

Answer

The maximum allowable pressure drop is typically 0.25 kPa (1 inch of water column) from the meter to the most remote appliance, ensuring adequate pressure at all appliance connections for proper combustion.

Red Seal Plumber 306A Practice Test

Red Seal Plumber 306A Practice Test

306A Gas Piping Systems 2