FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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Back end of system. The computer facility must also be housed to
endure the rigors of transportation and environmental extremes. A
climate controlled, insulated housing facility will protect the
computer system from these extremes. The computer facility must be
free from failure after power outages and should not be affected by
the mechanical vibration of operating laybarges.
12. REAL TIME IMAGE QUALIFICATION
Real time radiographie images should be qualified in the same ways as film
images. The ultimate factor should be the interpreter's ability to discern
the required portion of the image quality indicator. In contrast to film
radiography, consideration should be made to the "graininess" of the digital
image. Because these images are comprised of pixels, the spatial resolution
is higher when there are more pixels comprising a unit area of the image. If
conventional image quality indicators prove insufficient to determine image
sensitivity and contrast resolution, it may be necessary to use the CERL
image quality indicator or one of tailored design.
13. REAL TIME RADIOGRAPHIC INSPECTION CYCLE TIME
In real time radiography, the sequence of events involved in an inspection
cycle is:
1. Pipe stops at inspection station.
2. Radiation source is positioned at the weld location.
3. Radiation detector is positioned at the weld.
4. Radiographic image is collected and interpreted simultaneously.
Based on demonstrations provided by manufacturers of these real time radiography
systems, it is estimated that image collection will require, at most,
five seconds per diameter inch. Total cycle time will be a little more than
one minute for 8" 0 pipe, and a little more than three minutes for 40" 0
pipe. This allows 30 seconds for positioning of the source and mechanical
equipment. There is also the possibility of mounting more than one source
and detector on the pipe. In turn, the cycle time would decrease by a factor
equal to the reciprocal of the number of detectors.
14. REAL TIME RADIOGRAPHY COSTS
Pipeline contractors and owner companies traditionally contract inspection
work to third party inspection companies. If these companies will be
required to invest in the equipment that comprises a real time radiographie
system, then they will have to recover the cost of their investment through
charges to their clients.
One such scenario might be the following. Given that real time radiographie
systems range in price from $60,000 to $200,000 for a laybarge type system; a
price of $150,000 will be assumed. The inspection contractor would like to
recover the cost of the system, plus $30,000 each for interest and profit.
The inspector estimates that the useable life of the system will be three
years, and it will be used 60 days per year. The total cost which must be
recovered is $210,000. Based on the assumptions stated, the inspection