scope:

This Standard gives guidance on the specification, design, installation and operation of meter installations for low uncertainty flow measurement of piped Natural Gas (NG), NG blended with hydrogen and hydrogen operating within the pressure range exceeding 38 bar and not exceeding 100 bar.

This Standard covers the following types of meter:

• orifice meters

• turbine meters

• ultrasonic meters (USMs).

Note 1: The general principles may be applicable to other applications and types of meter (see Sub-Section 4.4).

Note 2: The legal status of each type is different and this may affect the choice of meter.

This Standard applies to installations supplied with NG, Liquefied Natural Gas (LNG) and Synthetic Natural Gas (SNG) blended with hydrogen and hydrogen in the gaseous phase only where the gas temperatures at the meter are within the range of -20°C to 75°C.

Note: They do not apply to installations supplied with Liquefied Petroleum Gas (LPG) or LPG/air systems, although the general philosophy and principles are relevant. For operations with other gases, for example air, oxygen or nitrogen, or outside these temperature limits, the manufacturers of individual items of equipment need to be consulted.

The field application of this Standard is, primarily, aimed at meter installations that require low uncertainty measurement, including:

• onshore installations where high accuracy measurement is necessary in the transfer of gas between shippers, suppliers and users, as appropriate, for example at compressor stations

• installations used at offtakes from high pressure gas transmission systems.

Note: The general principles may be applicable to other applications used for control purposes and plant monitoring at compressor stations, LNG and high pressure gas storage facilities.

IGEM/GM/8 gives guidelines on gas meter installations for MOP not exceeding 38 bar. This Standard provides detailed guidance for MOP exceeding 38 bar and may be used to supplement IGEM/GM/8 for turbine meters and USMs.

For information on pressure regulation associated with meter installations of MOP exceeding 38 bar and not exceeding 100 bar, reference should be made to IGEM/TD/13. For MOP exceeding 100 bar, similar principles are to be applied and expert advice sought.

All pressures quoted in this Standard are gauge pressure unless otherwise stated.

Italicised text is informative and does not represent formal requirements.

Appendices are informative and do not represent formal requirements unless specifically referenced in the main sections via the prescriptive terms "must", "shall" or "should".