However, many people know that the in-line inspection (ILI) tools, or intelligent pigs, are not perfect and their use is associated with a probability of detection, and some lack of precision in the evaluation and location of the flaws.

This uncertainty does not reduce the importance of ILI inspection and represents an area where more research and development can be done – even though pigging technology has improved dramatically in recent years.

Benefits of pigging testing

Both pipeline operators and pigging companies benefit from continuing development and research, including the test runs of pigging tools through trial facilities.

The worst place for running trial pigging runs is on a real pipeline under operation, due to many reasons related to risk, and interference in operations, as well as poor testing performance and test time extension.

The solution many pigging companies use is based on using private dedicated testing loops, although this can be a high-cost option. This type of facility, owned by the user, is applicable to internal development and initial test trials, but it is not the best place for a validation of technology and demonstrations to a pipeline operator, or potential customer. Instead, a common shared facility is the best solution.

The CTDUT facility

Centro de Tecnologia em Dutos (CTDUT) provides such a testing facility dedicated to pipeline integrity and management. Under a contract with a major pipeline operator, CTDUT has recently expanded its test loop by replacing original spools with a set of 32 spools, which include many different flaws intentionally made and properly mapped. Changing those spools in different combination allows CTDUT to convert its single loop into thousands of completely different pipelines.

In the beginning, the idea behind this project was to be able to evaluate different technologies and different brands under the same technology, and to assess what would assist future decisions regarding pipeline inspections. The final goal was to be able to select the best technology and tool for a particular pipeline inspection.

Intelligent pig evaluation, however, is not an easy job. It seems that there are a limited number of companies that agree to be evaluated under unknown and uncontrollable circumstances.

Currently, one pigging company has approached CTDUT to use its test facilities for evaluation, with good results and validated the intended use for the facility. However, to be considered a success, the project should be able to have more tools to work with and be able to establish a common baseline of performance.

Attractive options – developing company’s tools

The question arises: what could attract the pigging companies to participate in this project? The answer seems to be to change the fundamental idea of the project and turn it into a broader programme.

First of all, instead of inviting companies to be evaluated, pigging companies should be invited to have an opportunity to work on the development of their tools, without any associated evaluation, and performance data recorded for private use.

The defects mapping will be provided to the pigging companies and their data will be considered confidential. In fact, only the company’s analyst would be allowed to access the results.

After some reasonable time of development, companies might feel comfortable in demonstrating to their operator clients that they have a reliable system that can undergo a performance evaluation.

The test procedure that was applied to this first pigging company was based on five different pipeline inspections, which included the replacement of several spools on the test loop to configure those five different pipelines. Since the consistency of information was one of the items to be evaluated, two runs were performed for each pipeline simulation. The report generated after the inspection was analysed and compared against the reference with the known flaw mapping.

To perform the proposed development step, some pipelines could be configured and the pigging company would be informed of the defect mapping. After the runs, the pigging company would check the performance against the mapping and make the necessary improvements where needed.

Defects could include loss of wall thickness or cracks. As the technology develops and new challenges are faced, new defects can be included upon request.

In the end, the ILI tool can be considered ready for evaluation with a different set of spools, with defects located at different positions, allowing both operators and pigging companies to share the confidence in the proposed tool for a specific need.