Page 321 - Pipeline Pigging Technology

Pipeline Pigging Technology

The operation went smoothly; the RPIT did not stop, passing all pipeline
features without problems, and no mechanical damage to the pig occurred.
The tool was successfully triggered by the source, and the memory thereafter
stored all data from 170m of riser pipe. Values of both stand-off distance for
internal profile and wall thickness were recorded. Unfortunately, at many
places no readings were obtained. The unexpected presence of free wax in
the cold oil (below the cloud point) in the downstream riser caused absorp-
tion of the ultrasonic beams, and hence no readings were obtained; however,
at locations with no wax, useful data was nevertheless collected [4].

6. Crack detection and sizing

Ultrasonic tools are suitable not only for detection of metal loss; the
method is also very well suited to the detection of cracks [5].

REFERENCES

1. J.A.de Raad, 1987. Comparison between ultrasonic and magnetic flux pigs
for pipeline inspection with examples of ultrasonic pigs. Pipes & Pipelines
International, Jan-Feb, 32,1.
2. JA.de Raad, M.Ligthart and J.Labrujere, 1988. Testing and experience
collected with an ultrasonic riser pipe inspection tool. Paper presented at
the 7th Int.Conf.on Offshore Mechanics and Arctic Engineering, Houston,
Texas.
3. J.A.de Raad and J.v.d.Ent, 1989. Development, testing and experience
collected with an ultrasonic riser pipe inspection tool. Proc.l2th World
Conf.on NOT, Amsterdam, April, 1, pp 156-163.
4. J.Labrujere andJ.A.de Raad, 1988. The RPIT- an ultrasonic riser inspection
pig. Paper for Conf .Pipeline pigging and integrity monitoring, organized
by Pipes & Pipelines International, Aberdeen, Feb.
5. J.A.de Raad, 1990. Cable and other ultrasonic pigs. Pipes & Pipelines
International, March, 35, 2.

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