Girth weld cracking of long-distance oil and gas pipelines yields substantial harm to pipeline safety and may cause serious accidents. As of today, non-destructive testing has been one of the most common methods for predicting potential faults and ensuring safe operation. Classical pipeline non-destructive testing methods include magnetic flux leakage testing and the use of ultrasonic testing by electromagnetic acoustic transducers. However, they are incapable of identifying the defects in complex surfaces like girth welds. Magnetic flux leakage testing exhibits poor anti-interference abilities and low space resolution. Ultrasonic testing by electromagnetic acoustic transducers suffer from low conversion efficiency and poor signal quality. In order to overcome the disadvantages of conventional pipeline non-destructive testing methods, we propose an embedded eddy current testing system by leveraging image processing and neural networks. Hough transform and the contour extraction technique are employed to extract the characteristic features from the two-dimensional (2D) eddy current impedance image. Experiment results show that the system can effectively identify the girth weld defects, featuring an accuracy of up to 92%. The low power consumption and compactness of the proposed system makes it a great candidate for pipeline inner inspection.

Globally, the integrity of girth weld (GW) of oil and gas pipelines has increased as a concern due to failures with high consequences. A primary integrity issue to pipelines considers defects originating during field construction but over time may also be subject to external loads and stresses 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 levels of the inspection technologies. Research objectives of this paper are to characterize and summarize the applicability of inline inspection (ILI) technology of magnetic flux leakage 4 (MFL4) for inspection of defects related to pipeline GWs. Pull-through test and infield site excavations of operational pipelines have been collected and used for detection, internal/external (int/ext) identification, and sizing quantification. It can be concluded that the MFL4 technique is generally sensitive to lack of fusion or penetration, deep undercut, local thinning with results of both pull test and field data; while not sensitive to closed or very narrow small dimension cracks (narrower than 1 mm, less than 2 mm deep) as was observed in this study.

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.

Above ground indirect detections and random excavations that have applied the past years for buried long distance oil and gas pipelines can only identify some damaged coating locations. Hence, large number of field joint coating (FJC) failures happen unconsciously until they lead to failures of the pipelines. Based on the analysis of magnetic flux leakage (MFL) in-line inspection (ILI) signals, combined with the statistical results of 414 excavations from two different pipeline sections, a new method to identify the failed FJC is established. Though it can only identify FJC failures when there are signs of corrosion on pipe body, it is much more efficient and cost-saving. The concluded identification rule still needs more validations and improvements to be more applicable and accuracy.

The oil and gas pipeline failure database is comprised of many failure cases. Through failure, information gathering and analysis pipeline operators can find out the trend of failure occurrences and evaluate the performance of pipeline management. There are a number of institutions involved in failure data management. According to their managers, databases can be categorized as three types: 1) owned by one company, such as PetroChina, which collects and analyzes failure information in their own company; (2) managed by an authoritative management department that collects and analyzes failure information of companies under their responsibility, such as Pipeline & Hazardous Materials Safety Administration (PHMSA); (3) managed by an international group formed through cooperation and agreement between several countries and international companies who collect and analyze failure information of companies in the group, such as European Gas Pipeline Incident Data Group (EGIG). Failure in defining and information-gathering by different database managers is disscussed in this paper, which compares their failure rates and trends that are newly announced, as well. The failure of database management by PetroChina is emphasized by the author. Improvement of the database failure can be technically supportive for pipeline engineering critical assessments and would be important references for risk assessment, as the determination of failure probability and consequence are based on the statistical results. Failure incidents are precious wealth for companies, which can reveal the shortages of pipeline management and emergency rescue and enhance the operation safety.

Pipeline integrity management system is established by PetroChina Pipeline Company through research and discovery, according to the characteristics of pipelines managed. In this system, comprehensive system documents and standards of pipeline integrity management system are formed; technology system, including data collection, high consequence area identification, risk assessment, inspection and evaluation, maintenance and repair and other key technologies, is established. Through research and application of the system, the philosophy that "risk can be controlled, accidents can be prevented" is basically realized, which lead to the improvement of pipeline integrity management.