scope:

These Procedures, although written specifically for industrial and commercial premises, generally will be additionally applicable for domestic premises involving pipework larger than 28 mm diameter. For domestic pipework of not exceeding 28 mm diameter containing 2nd family gas, reference should be made to BS 6891 . For 3rd family gases, the equivalent Standard is BS 5482 although an upper size limit is not stated.

The Procedures deal with the selection of materials and components and methods of installation of pipework. For the purposes of these Procedures, installation pipework is considered to be downstream of a primary meter outlet or, when a primary meter is not fitted, downstream of the gas emergency control valve which normally is situated at the point where the gas supply enters the premises.

The Procedures apply for installation pipework designed to convey 2nd family gas, for example Natural Gas and 3rd family gas in the gaseous state, for example LPG, both as defined by BS 1179. It is likely that many of the procedures will be appropriate for 1st family gas, for example Town gas and other fuel gases, including those generated from landfill sites, but account shall be taken of their different constituents and the consequent effect on materials and operations.

The Procedures apply to installation pipework for a design pressure of not exceeding 7 bar for 2nd family gases and 2 bar for 3rd family gases. The value of the design pressure selected should take account of any foreseeable fault pressure immediately upstream of the primary meter.

LPG pressures normally will not exceed 2 bar, due to the possibility of liquefaction at low temperatures and hence the scope is limited to that pressure for LPG.

For pipework with a design pressure exceeding 7 bar, reference should be made to appropriate guidance, for example the British Gas pic publication IM/24.

The Procedures also apply to gas boosters, compressors and pre-mix machines, for a discharge pressure of not exceeding 7 bar.

The Procedures consider specifically pipe of steel, copper and polyethylene (PE). In certain applications, the use of other materials, such as stainless steel, may be specified and such materials should be used in accordance with appropriate British Standards or their National, European or International equivalents and/or the principles of these Procedures for materials of similar properties.

When considering components of installation pipework, for example valves, the Procedures cover a large selection of materials. However, the information is subject to the manufacturer's specification for the material in question.

The term "diameter" refers to the nominal inside diameter for steel and to the nomina outside diameter for copper and PE.

Pressures quoted are gauge pressures unless otherwise stated.

The term "pipework" refers to "installation pipework", as defined in the glossary.