Acoustic Emission Examination:Alarm - Acoustic Intelligent Pig for Detection and Registering Leakages | |
Transport of water-polluting fluids in pipes and pipelines, such as hydrocarbon products constitutes a severe risk to environment.
Leakages in such pipes do not only mean the loss of products but also a damage to environment. The usual test method for such pipes is the employment of intelligent pigs. Usually, intelligent pig systems only detect corrosion and longitudinal cracks but are not suitable for leakage tests. For that reason there was a need for new systems.
With acoustic emission (AE) examination the noises resulting from leakages are recorded by electrical sensors. As sound becomes weaker from the source to the point of recording it is difficult, expensive and sometimes even impossible to record the sound by means of fixly installed sensors. TÜV Austria has been applying this conventional AE procedure including cross correlation with maximal distances of 600 to 800 m successfully in special areas. The further development of the intelligent pig technology with transport of the sensors through the pipeline constitutes the only really promising alternative, though.
In cooperation with OMV AG TÜV Austria developed "ALARM", an acoustic intelligent pig for detecting and registering leakages.
Advantages of Intelligent Pigs
The intelligent pig is absolutely self-sufficient and needs no connecting or power supply cables. The casing contains the necessary power supply, the sensors and units for recording, processing and storing. The autonomous pig is forwarded through the pipeline with the transport media during normal operation for 24 to 100 hours, depending on the size. The available measurement distances for pipe diameters lie between 100 mm and 450 mm (4" to 18"). The smallest detectable leakage rate lies with ¡Ü 10 l.h-1, measured at one borehole ("worst case") and can be improved to 5 l.h-1 in case of optimal peripheral conditions. By using an odometer wheel a locating accuracy of 0,5% of the distance between the next artifical and natural markers can be achieved. It is possible to record pressure and temperature gradients along the whole length of the pipeline.
|
So far we have successfully tested more than 100 pipelines with the system ALARM.
