This paper presents the successful deployment of advanced eddy current array (ECA) probes for the inspection of intergranular stress corrosion cracking (IGSCC) present on the external surface of aboveground in-situ pipelines. During an inspection campaign carried out in 2020 and 2021 mainly on emulsion and produced gas pipelines, more than 20 indications were found over 20 kilometers of pipeline. These indications range from 5 mm to 400 mm long by 1 mm to 12 mm deep. The technology provided the pipeline operator a fast method for IGSCC detection leading to cost-effective inspection and maintenance planning, while preventing the risk of loss of product containment.
ECA technologies are not very well known in the oil and gas industry and are still undeservedly suffering from the bad reputation of traditional eddy current testing from twenty years ago. Eddy current techniques are often humorously compared to "black magic" in the sense that the results are difficult to understand, the probes are complicated to use, and only eddy current gurus can use it efficiently. However, ECA has evolved significantly over the past 15 years and is now much easier and more intuitive to use. It is in fact an extremely powerful technology when it comes to managing crack detection and depth sizing on critical assets like pipelines, pressure vessels, tanks, turbines, aircrafts, launch vehicles for the aerospace industry, and many others. ECA probes can be elaborate and precisely tailored for specific applications. Beyond that, the software capabilities are continuously evolving to bring this technology to another level. The ECA technology provides speed, high probability of detection (PoD), improved control over the human factor, impressive repeatability, and high accuracy on depth sizing. It is time for the industry to learn more about where this technology stands today.
The case study described in this paper showcases the use of ECA technologies for the inspection of in-situ aboveground pipelines for the oil sands industry. Following a few unfortunate surprises associated with IGSCC, the industry was desperately looking for an efficient solution to inspect oil emulsion (multiphase) and produced gas pipelines. Dry magnetic particles inspection (DMPI), which is the de facto method for pipeline direct assessment for cracks, was first considered for this work. However, this testing would have required an incredible amount of time to complete and extensive surface preparation (e.g., sandblasting, and careful painting as proper contrast is key with this technique). DMPI would also have been inevitably impacted by weather, environmental conditions, and outside temperature. Additionally, magnetic particle inspection is always subject to the human factor. Virtually all steps of an MPI inspection procedure relies heavily on the operator: surface preparation, magnetization, interpretation, and reporting. Although extremely useful in a wide variety of contexts and surface geometries, DMPI is intrinsically subject to human errors which heavily impacts repeatability and PoD during an inspection. Indeed, after having considered DMPI, it became obvious that this technique would require too much time, too many technicians, and offer limited confidence in the inspection results. Being able to collect data, map the results in an intuitive way, and archive digital records were also key features that only a digital inspection method could bring.
