Page 23 - igem-g-4 edition 2

IGEM/G/4 Edition 2
gasholder height equipment (gasholder contents gauge)
Equipment for measuring the height of a low pressure gasholder, and from this estimating its
contents.

gasholder station
Site where a gasholder or group of gasholders, together with the necessary control and
ancillary equipment, is located.

gauge readable movement (GRM)
Minimum pressure change that it is possible to read on a pressure gauge.

gauging
Method of checking for size and suitability of pipe into which insertion is to take place.

grades of release
Release, which is either continuous, primary or secondary grade. See individual definitions.

grid mat
Metal mesh mat.

grounded gasholder
Position of a watersealed gasholder representing a state of complete deflation and where all
lifts are supported on the rest blocks.

guide rollers, relating to a watersealed gasholder
Wheels (and axles) which engage with the column-guide or spiral-guide rails and transmit the
forces acting on a gasholder lift to the supports.

guided boring
Steerable system for the installation of pipes, conduits and cables using a surface-launched
drilling rig.

hardware alarm
Alarm operated directly by equipment installed for that purpose.

hazard
Situation with a potential for human injury, damage to property, damage to the environment
or a combination of these.

hazard analysis
Identification of undesired events which leads to the materialisation of a hazard, the analysis
of the mechanisms by which these undesired events could occur and usually the estimation of
the extent, magnitude and likelihood of any harmful effects.

hazard range
Distance from the release point or source of hazard to a defined level of harm or type of
hazard.

hazard and operability study (HAZOP)
Systematic study carried out by application of guide words to identify all deviations from
design intent with undesirable effects for safety or operability.

19
©IGEM, IGEM House, High Street, Kegworth, Derbyshire, DE74 2DA. Website: www.igem.org.uk