PRCI PR-250-9719

L51947e

Feole Technologies Inc.

Need: Several NDT technologies are in use today for evaluating internal gas pipeline corrosion. Each technology has advantages but is marred by numerous drawbacks as well. Inspection firms typically select more than one technology in order to maximize the confidence that flaws will be detected before leaks or catastrophic failures occur. Emerging NDT technologies must be evaluated for the possibility of improving the efficiency, accuracy or economy of the complete corrosion monitoring solution.

Result: This report discusses the relevant technologies and presents a laboratory trial of an x-ray flat panel imager in locating and quantifying internal pipeline corrosion. The objectives or this report are to discuss relevant NDT technologies for pipeline inspection, covering the advantages and drawbacks of each technology; To discuss some methods for the quantitative interpretation of radiographs and its performance in combination with various radiographic technologies; To select some candidate equipment for laboratory and field trials; and to conduct a laboratory test of equipment and methods in order to demonstrate the efficiency of the real time radioscopic system in locating and quantifying the approximate depth of corrosion in two pipeline samples.

Benefit: Radiographs were made. Intensity readings were extracted using imaging software. The wall thickness loss was calculated from the intensity readings. Contact measurements were made in order to determine the actual wall thickness loss. The difference between the two measurement methods, then, is the error of the calculated values. The errors were arbitrarily small, ranging from -0.003" to +0.026" for wall thickness losses ranging from 0.080" to 0.271". The calculated values almost all underestimated the thickness loss by small amounts and large amounts. The worst absolute error was a measured 0.126" loss that calculated as an 0.100" loss, an underestimation by 0.026". The worst relative error was the same one, an underestimation by 21%. Calculations of wall thickness from radiographic data showed promising accuracy when compared with caliper measurements of the same corrosion.

Product Details

Published:

01/01/2001

Number of Pages:

40

File Size:

1 file , 940 KB