Lifetime benefits from different defect assessment methods
Proceedings Publication Date
Wolfgang Schmidt
Dr. Christian Mayer, Wolfgang Schmidt
Part of the proceedings of
The use of modern intelligent pigs does not only substantially contribute to a secure pipeline operation but also requires efficient and reliable evaluation methods for processing of the large information quantity.

In addition to the individual deterministic evaluation of all defect indications also a probabilistic assessment of the integral pipeline safety level considering most different influencing factors is nowadays increasingly demanded. Several international standards are in use for the defect assessment of pipelines. If only length and depth of a corrosion defect are known, typical assessment methods include ASME B31G, simplified RSTRENG, or DNV-RP F101.

In this lecture, we compare experimental results for the failure pressure of defective pipes to the predictions of the aforementioned methods and to results based on a defect evaluation method developed by TÜV Rheinland, which is in use for more than 30 years and which has been continuously advanced since then.

The comparative evaluation shows very good agreement between the experimental results both for DNV-RP F101 and the TÜV Rheinland method, with the latter being slightly more accurate. By comparison, the results obtained by using ASME B31G or simplified RSTRENG show a larger deviation to the measured burst pressures.

The second part of the lecture will show the effect of the forecast accuracy of the chosen assessment method on the results of a probabilistic safety evaluation.

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