GIS 04: Allowable leakage for existing standard installations operating at 1.13 kPa

Purpose

The Gas Safety Act 1997 and Gas Safety (Gas Installation) Regulations 2018 prescribe AS/NZS 5601.1 Gas Installations Part 1: General installations as the standard for gas installations.

AS/NZS 5601.1 clause 3.5.2 requires all existing gas installations which have been altered, repaired or extended to be tested for leakage.

This sheet provides guidance on allowable leakage rates for existing standard natural gas installations with pipework volume up to 30 litres, at a maximum operating pressure of 1.275 kPa ± 0.05 kPa.

There is no allowable leakage rate for:

• LPG installations
• natural gas installations with a metering or operating pressure above 1.275 kPa ± 0.05 kPa
• standard gas installations with a volume greater than 30 litres
• complex gas installations as defined in the Gas Safety Act.

Such installations, whether new or existing, shall have no loss of pressure when tested to the requirements of AS/NZS 5601.1.

Guidelines

Test before you start work

Before commencing any new work, carry out a leakage test on the existing gas installation.

If a leak is found, make arrangements for the fault to be fixed before the new work is connected. Methods for leakage tests are explained in AS/NZS 5601.1 Appendix E.

Finding gas leaks and when to apply the allowable leakage rate

Gasfitters must make all reasonable efforts to locate and fix any gas leaks identified.

Gas leaks can be identified using a soapy water solution, leak detection fluid or other suitable leakage detection method. Sometimes slight leakage occurs which is hard to detect. Such leakage is often due to a combination of old appliances, worn gas valves and degraded pipe joints.

When reasonable efforts to locate and fix a leak have proven unsuccessful, if there is no smell of gas an allowable leakage rate assessment can be made in accordance with this sheet.

Allowable leakage rate for natural gas

Energy Safe Victoria’s policy regarding allowable leakage rate is as follows:

• New installations: There must be no loss of pressure when a new installation is tested to the requirements of AS/NZS 5601.1. Therefore, there is no allowable leakage rate for any new installation.
• Existing natural gas installations: Table 1 specifies the allowable pressure drop for an existing standard natural gas installation with a pipe volume no greater than 30 litres.

If the pressure drop exceeds the specified limit, then either:

• all leaks must be located and rectified, or
  • the installation must be made safe by isolating the faulty appliance or section of piping.

Allowable pressure drop

Use table 1 as a guide for establishing the maximum allowable gas pressure drop when tested at operating pressure 1.275 kPa ± 0.05 kPa.

Table 1 - Acceptable pressure drops for existing installations (test period = 5 min)

Using a manometer to determine the leakage rate

For an existing standard natural gas installation, with a volume no greater than 30 litres, the leakage rate may be determined using a manometer. Complete the test with all appliances connected.

Determining pipe volume

AS/NZS 5601.1 Appendix D4 includes guidance on how to calculate the approximate volume of the pipe. Other suitable methods to calculate the piping volume may also be used.