Identification: The process
of differentiating a signal caused by one type of defect from signals caused
by other types of defects or system features. Identification is particularly
important for mechanical damage defects because their signals are so small that
they can be mistaken as due to benign conditions. Mechanical-damage signals
are also small compared to signals from metal loss and features such as valves.
Imperfection: An anomaly
in a system that will not result in a failure at pressures below those that
produce nominal stresses equal to the specified minimum yield stress of a given
Incident: An event that,
according to the U.S. Department of Transportation Office of Pipeline Safety,
involves fatalities, injuries, property damage in excess of $50,000, unintentional
release of natural gas, customer outages, or other conditions that, in the opinion
of the pipeline operator, are significant enough that they should be reported.
Inclusions: Foreign material
or particles in a metal matrix. These are usually compounds, such as oxides,
sulfides, or silicates, but may be any substance that is foreign to the matrix
whether it is soluble or insoluble.
Indication: A finding
of a nondestructive testing inspection.
Describes measurement of any parameters that may influence, or are influenced
by, metal loss or corrosion.
Induction Coil: A type
of sensor that measures the rate of change in magnetic flux density. Induction
coils do not require power to operate, but have a minimum inspection speed requirement.
In-Line Inspection (ILI):
The inspection of a pipeline from the interior of the pipe using an in-line
inspection tool. Also called Intelligent or Smart Pigging.
In-Line Inspection Tool (ILI Tool):
The device or vehicle, also known as an intelligent or smart pig that uses
a nondestructive testing technique to inspect the wall of a pipe.
In-Line Monitoring: Refers
to installation of monitoring equipment directly in the bulk fluid of the process,
but data acquisition requires extraction of probes or process shutdown for analysis,
e.g., mass-loss coupons.
Inspection: (1) The process
of examining a pipe using a nondestructive testing technique to look for anomalies
or to evaluate the nature or severity of an indication. (2) The process of running
a configuration tool or an in-line inspection tool through a pipe to detect
Instrumented Pig Tool:
Older term for in-line inspection tools.
Intelligent Tool: See
in-line inspection tool.
Interaction Rules: Specifications
that establish spacing criteria between anomalies or defects. If the indications
or defects are proximate to one another within the criteria, the anomaly or
defect is treated as a single larger unit for engineering analysis purposes.
Corrosion where grains are dislodged from metallic alloys as a result of
highly localized dissolution along the grain boundaries.
Intergranular Crack: Crack
growth or crack path that is between the grains of a metal.
Requires penetration through the pipe or vessel wall to gain access to the interior
of the equipment.
Iron count: Corrosion
monitoring technique which provides an indication of the water corrosion of
iron pipes through an analysis of the iron content in water which issues from