Page 43 - igem-g-4 edition 2

IGEM/G/4 Edition 2
shear stress
Stress resisting the relative slippage of cross-sectional planes. The stress is produced by the
shear force and/or torsional moment acting on the pipe or component cross-section.

shunt duct system
Shared/common flue system constructed of a number of smaller individual flues.

shut-down
Shutting off of all fuel and ignition energy.

singularities
Undefined or indefinitely large values often resulting from a division by zero.

siphon
Vessel installed at a low point in a pipeline or pipework, to collect condensate and other
liquids.

slam-shut valve (SSV)
Valve that is designed to close quickly in the event of an abnormal (usually excess) pressure
being detected downstream, and which requires manual intervention to reset.

sleeve
Encasement inserted into a prepared hole in a structure for the reception of a pipe.

slug purging
Purging by the formation of a barrier of inert gas between fuel gas and air.

slurry
Fluid used in microtunnelling, sometimes bentonite or water, which is used as face support
medium and also as a material transporter by pumping to the surface.

snubber
Combination of components and volumes provided for damping out flow and pressure
pulsations produced by a gas compressor.

societal risk
Relationship between the frequency and number of people in a given population suffering a
specified level of harm from the realisation of specific hazards.

societal risk criteria
Criteria relating to the likelihood of a number of people suffering a specified level of harm in a
given population from the realisation of specified hazards.

sole plate
Generally, the first timber component to be fixed, the sole plate is fixed to the substructure
over a dpc and thus forms the base upon which the timber structure is erected.

source
Point on a distribution system or individual service (pipe) which is capable of supplying a load,
i.e. the outlet of a regulator or point on a distribution system capable of providing a supply to
a new distribution system.

source of release
Point or location from which flammable gas may be released into the atmosphere such that a
flammable gas atmosphere could be formed.

spiral-guided gasholder
Watersealed gasholder in which the lifts are guided by carriages operating on spiral rails,
o
usually set at an angle of 45 .

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