GE Oil & Gas - PII Pipeline Solutions SPRING 2008

EmatScan™ Gen III
New sensor delivers real defect discrimination improvements
The goal of every in-line inspection (ILI) is to collect sufficient information from a pipeline to allow an operator to better manage the service and maintenance of the line in a cost effective manner. Distinguishing between injurious and non-injurious features is the first key step in assessing the criticality of issues facing the operator.

Most ILI vendors develop their new products using features that are manufactured into a pipe spool. This approach is good for initial assessment of new designs, but real defects in operational pipelines have different geometries that cannot be simulated with a manufactured process. Therefore the performance of the development in real pipelines is often disappointing.

A superior solution
GE Oil & Gas - PII Pipeline Solutions has utilized its extensive EMAT experience in over 3,000 km of operational pipelines to provide improvements to our latest EmatScan tool. To verify that these improvements will deliver the expected results, PII took pipe spools provided by a customer and containing real features and utilized them in our advanced test loop in Stutensee, Germany. These spools contained both real SCC and real laminations. This was a rare opportunity because most customers do not cut out non-injurious features. An earlier version of EmatScan inspected the line successfully, but the features in this section were misclassified. So, the spool represents the type of features that are the most challenging for the technology in this customer's pipeline.

Using a unique method of comparing distinct signal responses from multiple independent sensor systems, PII's new EmatScan tool exhibits a clear ability to distinguish between laminations and SCC.

Analysis incorporating this information will remove all the guesswork in making the classification.

UltraScan™ CD Inspection followed by Engineering Crack Assessment

The Moomba-to-Sydney Gas Pipeline, operated by Agility on behalf of its owner, The Australia Pipeline Trust (APA), transports natural gas from central Australia to Sydney on the east coast – more than 1,300 km.

The pipeline was commissioned in 1976, and a failure occurred in 1982 due to SCC cracking. The pipeline’s maximum allowable operating pressure (MAOP) was down-rated to 6 MPa from a design MAOP of 6.895MPa, and a length of approximately 30 km was replaced. The operating strategy was changed to mitigate the probability of SCC occurring or developing.

In 2004, during excavations following a GE Oil & Gas – PII Pipeline Solutions metal loss survey, further significant SCC colonies were discovered. The MAOP was further down-rated to 5.5 MPa – a significant reduction in throughput for such an important pipeline.

In 2004-05, Agility contracted with PII to perform an UltraScan™ CD survey to investigate the prevalence of SCC in the first section of the pipeline. Following a successful survey, a number of excavations confirmed the tool findings. Defect locations, lengths and depths had all been predicted accurately.

In addition to investigating a significant repair program based on the UltraScan™ CD results, Agility also contracted with PII’s Integrity Services group to perform detailed engineering critical assessments of the crack colonies. Particular attention was given to their immediate significance to the integrity of the pipeline; and to analyzing potential growth mechanisms to predict the number of significant features arising as a function of time. In addition, material testing was carried out on samples of the pipe.

As a result of this work, Agility was able to develop a strategy for the safe future operation of the pipeline with the aim of reinstating the original MAOP while assuring the integrity of the line.

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