Page 408 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

Glossaryi383
pressure of a vessel. The valve is often designed to close SCADA. Supervisory control and data acquisition. A
again when the vessel pressure is again below the set point. SCADA system allows conditions along the pipeline to be
Product hazard. A numerical score that reflects the relative monitored and certain types of equipment to be controlled
danger of the material being transported through the from a central location. This is a system to gather informa-
pipeline. This relative ranking of the product characteristics tion such as pressures and flows from remote field loca-
considers acute and chronic hazards such as flammability, tions and regularly transmit this information to a central
toxicity, and carcinogenicity. facility where the data can be monitored and analyzed.
psi, psig, psia. Pounds per square inch, pounds per square Through this same system, the central facility can often
gauge, or pounds per square absolute. This is the normal unit issue commands to the remote sites for actions such as
of pressure measurement in the United States. The gauge opening and closing valves and starting and stopping
pressure is psig and is the reading that is seen on a pressure pumps.
gauge calibrated to zero under atmospheric pressure. SCC. Stress corrosion cracking. This is a potential fallure
Therefore, psig does not separate atmospheric pressure from mechanism that is a combination of mechanical loadings
the reading seen on the gauge. Zero psig is equal to about (stTess) and corrosion. It is often an initiating or contributing
14.7 psia, depending on the exact atmospheric pressure of factor in fatigue failures.
the area. Seam weld. Generally refers to the welds of longitudinal
Public education. The program sponsored by pipeline coin- seams of the pipe produced during certain pipeline manufac-
panies to teach the general public about the pipeline industry. turing processes such as ERW.
The emphasis is usually on how to avoid and report threats to Secondary containment. Any system designed to catch and
the pipeline and what precautions to take should a leak be retain escaping product if a portion of the pipeline system
observed. fails. Levees and impermeable liners around tanks serve as
secondary containment.
Rectifier. A device that converts AC electricity into DC elec- Seismic event. A sudden motion or trembling of the earth
tricity and delivers the current onto the pipeline for purposes caused by the abrupt release of slowly accumulated strain in
of cathodic protection. the earth’s crust related to faulting or volcanism also known
Relative risk value. Also relative risk rating or score. This as earthquakes.
number represents the relative risk of a section of pipeline in SMYS. Specified minimum yield strength. The amount of
the environment and operating climate considered during the stress a material can withstand before permanent deforma-
evaluation. tion (yielding) occurs. This value is obtained from the manu-
Release quantity. This is the quantity of spilled material that facturer of the material.
will trigger an EPA investigation. Possible categories are I-, Stress. The internal forces acting on the smallest unit of a
IO-, 100-, 1000-, and 5000-pound spills. More hazardous material, normally expressed in psi (in the United States).
substances trigger investigations at lower release amounts. When an external loading such as a heavy weight is placed
For this risk assessment model. release quantities have been on a material, a level of stress is created in the material as it
assigned to substances not normally regulated by the EPA. resists deformation from the load.
Remotely operated valve. A mechanical device that pre- Surge pressure. Also referred to as wuterhumrner: this IS a
vents flow in a pipeline and is designed to operate on receipt phenomenon in pipeline operations characterized by a sud-
of a signal transmitted from another location. den increase in internal pressure. This surge is often caused
Risk. The probability and consequences of a damaging by the transformation ofkinetic energy to potential energy as
event. a stream of fluid is suddenly stopped.
Riverine. The riverine system includes all wetlands and deep
habitats contained in natural or artificial channels periodi- Third party. Any individual or group not employed by the
cally or continuously containing flowing water, or which pipeline owner or contracting with the pipeline owner. Third-
forms a connecting link between the two bodies of standing party damages occur when an individual not associated with
water. Upland islands or palustrine wetlands may occur in the pipeline in any way accidentally strikes the pipeline
the channel, but they are not part ofthe riverine system. while performing some nonrelated activity.
ROW. Right of way. The land above the buried pipeline (or
below the aboveground pipeline) that is under the control of Wall thickness. The dimension measurement between a
the pipeline owner. This is usually a strip of land several point on the inside surface ofthe pipe and the closest point on
yards wide that has been leased or purchased by the pipeline the outside surface of the pipe. This is the thickness of the
company. pipe material.
Safety device. A pneumatic, mechanical, or electrical device Yield point. In general, this is the point. defined in terms of
that is designed to prevent a hazard from occurring or to an amount of stress, at which inelastic deformation takes
reduce the consequences of the hazard. Examples include place. Up to this point, the material will return to its original
pressure relief valves, pressure switches, automatic valves, shape when the stress is removed; past this point. the stress
and all automatic pump shutdown devices. has permanently deformed the material.