Abstract

Globally, more and more attention has been paid to the integrity of Girth Welds (GW) of oil and gas pipelines due to their failures with high consequences. A primary concern is that defects originate during field construction but over time may be subject to external loads due to earth movement. GW defects in newly built pipelines are also assumed to exist but would be much smaller in size, and more difficult to detect, which motivated the investigation into minimum defect detection capabilities of the inspection technologies. This study presents the evaluation results of UltraScan™ Circumferential Crack-Like Detection (USCCD) technology for oil pipeline GW inspection, based upon the pull test and in field data from Inline Inspection (ILI) of pipeline by PetroChina Pipeline Company (PPC) using GE PII (General Electric Company, Pipeline Integrity Inspection) 32” UltraScan™ CCD Tool. The performance of USCCD is given according to the ILI data, pull test results and dig NDE (Non-Destructive Examination). It can be concluded that crack-like defects with clear edges can be detected during ultrasonic propagation; however, the irregular shape of weld makes the inspection more difficult. It is still a challenge to identify the type of defects, and depth sizing can only be classified not quantified, which would require more excavations. However, this technology is feasible for the alternative technology of GW defect inspection.

Highlights

  • Girth Welds (GWs) of oil and gas pipelines are more and more concerning because of frequent failures and the accompanying high consequences [1]

  • For determination of POD, 102 defects with open width of 0.8mm were taken into account

  • The defects were categorized with respect to their position relative to the weld into two groups: defects in test defects were categorized with respect to their position relative to the weld into two groups: weld and those at weld

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Summary

Introduction

Girth Welds (GWs) of oil and gas pipelines are more and more concerning because of frequent failures and the accompanying high consequences [1]. As conventional MFL (Magnetic Flux Leakage) is universally used in the industry and qualitatively known to be sensitive to volumetric metal loss [4,5,6], ultrasonic crack detection is a superior method for cracks and crack-like defects, because it is more sensitive to defect edges that are close to each other [7,8,9,10]. The objective of this test was to evaluate and quantify the performance for UltraScan. By PetroChina Pipeline Company (PPC) using GE PII 32” UltraScanTM CCD Tool

Ultrasonic
Description of Test
Description of Pull Testing
Description
Results for for GW
Depth Sizing
Length Sizing Accuracy
11. Picture
13. Signal
Conclusions

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