Gas Safe ACS - Accredited Certification Scheme Pipework and Fittings Questions and Answers

Question 1

An engineer is installing 22mm copper pipework to supply a domestic gas boiler. According to BS 6891, what is the correct method for protecting this pipework where it passes through a solid wall?

Accepted Answer

Ensure the pipe is sleeved for its full length within the wall, and seal the annular space at one end.

Answer

Wrap the pipe in denso tape and seal the ends.

Answer

Paint the pipe with a corrosion-resistant paint before embedding it directly in the mortar.

Answer

Encase the pipe in a larger plastic pipe and fill the void with expanding foam.

Question 2

When carrying out a tightness test on a new domestic gas installation with a total volume of 0.015 m³, what is the standard duration for the stabilisation period after pressurising the system to 20 mbar?

Accepted Answer

1 minute

Answer

5 minutes

Answer

10 minutes

Answer

2 minutes

Question 3

Which of the following jointing methods is NOT permissible for connecting steel pipework on a domestic Natural Gas installation operating at low pressure (21 mbar)?

Accepted Answer

Capillary soft solder fittings.

Answer

Longscrew connectors with appropriate sealant.

Answer

Welded joints.

Answer

Tapered thread screw joints.

Question 4

A gas engineer needs to install pipework through a timber floor joist. According to BS 6891 and building regulations, what is the maximum diameter of a hole that can be drilled through the centre of a 200mm deep joist without requiring structural calculations?

Accepted Answer

50mm

Answer

65mm

Answer

75mm

Answer

100mm

Question 5

According to the Gas Safety (Installation and Use) Regulations 1998, what is a key requirement for installation pipework run in an unventilated void, such as a floor duct or ceiling space?

Accepted Answer

The pipework must be contained within a ventilated duct.

Answer

The pipework must be painted yellow for easy identification.

Answer

The pipework must be constructed of continuously welded steel.

Answer

The void must be filled with a non-combustible insulation material.

Question 6

An engineer is replacing a section of 28mm gas pipework. Before cutting into the existing pipe, the section must be safely purged. What is the primary purpose of purging the pipework 'out of service'?

Accepted Answer

To displace the flammable gas with air or an inert gas to prevent an explosive mixture.

Answer

To increase the pressure in the pipe to check for weaknesses.

Answer

To clean the inside of the pipe from debris and corrosion.

Answer

To introduce a pleasant smell to the gas for easier leak detection.

An engineer is installing 22mm copper pipework to supply a domestic gas boiler.According to BS 6891, what is the correct method for protecting this pipework where it passes through a solid wall?

An engineer is installing 22mm copper pipework to supply a domestic gas boiler.
According to BS 6891, what is the correct method for protecting this pipework where it passes through a solid wall?