Page 404 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

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Appendix G1379

Appendix G
Examples of

Common Pipeline

Inspection and
Survey Techniques

Inspection or test ppe Purpose Attributes
Pressure testing (hydrostatic Commonly used as a pre-service integrity A regulatory requirement for new pipe sections, to uprate
pressure testing) validation ofthe pipe and components existing pipe sections. and conversion from vapor to liquid
by pressurizing to a level above the service.
intended operating pressure.
Destructively “detects” defects so they do Done by sectioning line according to terrain elevations.
not subsequently fail while in service. One or more valve sections can be included within
test segment.
Allows the establishment ofthe real Requirements and procedures defined in regulations and
minimum strength ofthe pipeline and industry standards.
components, as opposed to the mill tensile
test, which is based on a sample ofpipe.
Hydrotesting service is usually provided by a specialty
contractor overseen by operating company staff.
Cathodic protection (CP) Determines the adequacy of cathodic Rectifier inspections are done to ensure that the rectifiers
inspections and surveys protection voltages and currents for are in service and providing the required impressed
protecting the pipeline against current for cathodic protection.
corrosion and to detect areas of
potentially defective coating.
Station tests or surveys are done to measure CP voltages at
test station locations. This also includes readings taken at
pipe casings under roads and railway crossings.
Various forms ofclose interval surveys (CIS) are taken at
intervals of 2 to IO ft along a pipeline to provide a profile
along the line to greater resolution than can be obtained
with a station survey.
In-line inspection (ILI) Detects areas of anomalies, such as metal Automated internal inspection tools or “smart pigs” vary in
loss, deformations, cracks, dents, anomaly types that can be detected and terms of degree
gouges, and laminations. ofresolution. Services are provided by a specialty
pigging contractor. Common technologles are ultrasonic
and magnetic flux leakage (see Chapter 5). Results often
require expertise in interpreting data. Either part or all of a
pipeline is inspected depending on the location of pig
launching and receiver equipment and the size and
geometry of the pipeline system.
Continued