Page 405 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

380 Examples of Common Pipeline Inspection and Survey Techniques
Inspection or test type Purpose Attributes

Manual ultrasonic wall Determines wall thickness and identifies Manually held instrument used in conjunction with exposed
thickness measurement areas of metal loss by direct pipe inspections. Requires coating removal.
measurement ofpipe wall thickness.
Leak surveys Finds active leaks over a hydrocarbon Usually includes handheld instrumentation to detect
pipeline. hydrocarbon vapors.
Water crossing surveys Determines elevation profile and depth of May require divers to probe or use instrumentation to locate
cover beneath waterway. depth ofpipe below stream or lake bottom.
Depth of cover surveys Determines actual amount of cover Depth is measured by instrument or by physical “probing”
over pipeline. ofthe pipeline.
Visual surveys Identifies any adverse conditions associated Done in conjunction with finding exposed pipe or exposing
with coating or pipe, such as corrosion, pipe for inspection by digging at various pipe locations.
dents, scrapes, gouges, or deteriorating The hare pipe can only be examined when the coating is
or damaged coating. removed.
Acoustic monitoring Finds discontinuities in metallic pathways; Impressed sound waves are analyzed for discontinuities or
used in reinforced concrete pipe. active failure.
Subsurface coating condition Evaluates coating condition of buried steel Impresses a signal onto a pipeline and measures attenuation
pipeline. of signal to determine signal leakage through coating.
Nondestructive testing Uses techniques such as ultrasonic, Usually done in conjunction with visual inspection; can he
magnetic particle, dye penetrant, etc., to done on coating or on pipe wall.
find pipe wall flaws that are hard to detect
with the naked eye. Can also include
testingof coating properties such as
thickness and numbers of holidays.
Ground patrols Identifies external conditions that might These apply more to the effects of external factors on the
and aerial surveys adversely affect the pipeline, such as third pipeline and the detection of leaks than to factors
party activity and ROW encroachments. associated with the conditions ofthe pipe itself.
Also used as a means of detecting leaks. They complement visual surveys.