Page 292 - Corrosion Engineering Principles and Practice

Technique Advantages Disadvantages C o r r o s i o n b y W a t e r 267
Sonic/acoustic Widely practiced Percentage of leaks missed by
leak detection Known to find leaks the technique is unknown
accurately Currently works best in metal
Known to find leaks of water lines
different sizes Only gives information on the
Operates from outside current condition of the line (the
the water line tool has little predictive value)
Background noise problems
Remote field Most advanced More expensive than leak
inspection technique currently detection
(hydroscope) available Requires access to the inside
Detects areas of of the water line, which may
corrosion pitting, as require cleaning
well as through holes Knowledge of the relationship
Can be used to give an between pit size and residual life
estimate of the future of the pipe is not yet complete
life of a line Limited to pits of less than
3
3 cm in size.
Magnetic flux Established technology Not yet commercially available
leakage in oil and gas industry for water lines
Known to be capable of Requires access to and
detecting small defects complete cleaning of the
and through holes in inside of the pipe
steel pipe
Ultrasound Most versatile NDE Technique will not work
technique through tuberculation
Established technology Not yet commercially available
in oil industry for water lines
Requires access to and
complete cleaning of the
inside of the pipe
Soil corrosivity Simple to conduct Cities may have similar levels
measurements May act as a screening of corrosivity across their
mechanism for more region, making use difficult
expensive methods Do not always correlate with
corrosion reality
Half-cell Simple to conduct Factors such as stray currents
potential May act as a screening and soil conditions may affect
measurements mechanism for more readings
expensive methods Accuracy of results depends on
Well established as distance between readings
method to detect Small areas of localized
corrosion activity in corrosion can not be detected
buried objects

TABLE 8.3 (continued)