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Calibration Dig: Exploratory
excavation to validate findings of an in-line inspection tool with the purpose
of improving data interpretation.
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Caliper Pig: A configuration
pig designed to record conditions, such as dents, wrinkles, ovality, bend radius
and angle, and occasionally indications of significant internal corrosion, by
sensing the shape of the internal surface of the pipe (also referred to as geometry
pig).
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Camera Pig: A configuration
pig that carries a video or film camera and light sources for photographing
the inside surface of a pipeline on an intermittent or continuous basis.
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Cathodic Protection (CP):
A technique to reduce the corrosion of a metal surface by making that surface
the cathode of an electrochemical cell or system.
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Cavitation: The formation
and rapid collapse within a liquid of cavities or bubbles that contain vapor
or gas or both causing the degradation of a solid body. (This may include loss
of material, surface deformation, or changes in properties or appearance).
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Chainage: Position of
a point along the pipeline, typically taken from a fixed reference such as a
valve.
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Characterization: The
process of quantifying the size, shape, orientation, and location of an anomaly,
defect, or critical defect after it has been detected. There are many degrees
to which characterization can be successful. For example, one type of characterization
of a mechanical-damage defect may be to determine whether the defect contains
a cold worked region (severe) or not (less severe).
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Characterize: To qualify
the type, size, shape, orientation, and location of an anomaly.
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Check Valve: Valve that
prevents reverse flow. Can cause damage to in-line inspection tools if not fully
opened.
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Chemical analysis: Different
types of chemical analyses can provide valuable information in corrosion monitoring
programs. The measurement of pH, conductivity, dissolved oxygen, metallic and
other ion concentrations, water alkalinity, concentration of suspended solids,
inhibitor concentrations and scaling indices all fall within this domain.
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Class Location: A criterion
for pipeline design set by the United States Code of Federal Regulations, Title
49, Part 192." Class 1 is rural and Class 4 is heavily populated. A class location
is based on the number and type of buildings situated in an area that extends
220 yd (200 m) on either side of the centerline of any continuous 1.0-mile (1.6-km)
length of a gas pipeline.
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Classify: To separate
the cause of indications into one of three categories, namely, anomalies, non-relevant
conditions, or system components.
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Cleaning Pig: A utility
pig that uses cups, scrapers, or brushes to remove dirt, rust, mill scale, and
other debris from the pipeline. Cleaning pigs are utilized to increase the operating
efficiency of a pipeline or to facilitate inspection of the pipeline.
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Coating Disbondment: The
loss of adhesion between a coating and the substrate.
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Coil Sensor: See Induction
Coil.
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Cold working: Distortion
of the grains in the vicinity of a gouge. Cold working often occurs immediately
under the visible gouge and can significantly reduce the mechanical properties
of a pipe steel.
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Compression: (1) The process
of increasing the pressure of gas to maintain its flow in a pipeline system.
Compressing gas is analogous to pumping liquids, such as water or oil. (2) The
process of reducing the amount of data to be stored in an in-line inspection
tool.
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Condition monitoring:
Determination of the health or condition of a machine or system by analysis
of signals generated. Measurements may be taken either periodically or continuously,
and can cover a very wide range of features including corrosion.
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Configuration Pig: An
instrumented pig that collects data relating to the inner contour of a pipe
wall or of the pipeline: geometry pigs, camera pigs, and mapping pigs are types
of configuration pigs.
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Corrosion: The deterioration
of a material, usually a metal, that results from a reaction with its environment.
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Corrosion Pit: Local concentrated-cell
corrosion on the external or internal surfaces that results from the generation
of a potential (voltage) difference set up by variations in oxygen concentrations
within and outside the pit. The oxygen-starved pit acts as the anode and the
pipe surface acts as the cathode.
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Coupon, Weight loss: A
removable test strip or disk of metal used in a gaseous or liquid medium to
provide an indication of the corrosivity between the medium and that type of
metal.
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Crack Coalescence: Joining
of two or more cracks in close proximity to form a longer crack.
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Crack, Cracking: Very
narrow elongated defects caused by mechanical splitting into parts.
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Crevice corrosion: Localized
corrosion of a metal surface at, or immediately adjacent to, an area that is
shielded from full exposure to the environment because of close proximity between
the metal and the surface of another material.
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Critical Defect: A defect
for which an analysis indicates that immediate attention is required.
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Cultures: Micro-organism,
tissue or organ on a surface specially prepared to cultivate its growth.
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Cup Pig: A utility pig
that is supported and driven by cups made of a resilient material such as neoprene
or polyurethane. At least one of the cups forms a piston-like seal inside the
pipeline.
