Expert Answers to Pipeline Operators’ Mechanical Damage Questions

Understand some of the trickiest calls in pipeline integrity — mechanical damage

Mechanical damage can be one of the most tricky – and consequential – anomalies to assess in a pipeline. We’ve asked our Chief Data Scientist, Rick Desaulniers, to answer some key mechanical damage questions that pipeline operators ask us.

Q: Is there a Probability of Detection for ERW welds with the UHR tools, and therefore the ability to detect deformation anomalies in proximity to an ERW weld?

Answer: The short answer is — yes — ENTEGRA^®’s UHR ILI System CAN detect ERW seams. We all know that operators must deal with metal loss on the seam, which is a trigger for potentially immediate investigation. Therefore, it is even more important to be able to detect ERW seams and identify anomalies in relation to the seam, especially in mechanical damage scenarios. This would raise an anomaly up the priority list even further. With ENTEGRA UHR, even if the metal loss component is adjacent to or running through the seam, that is something that can be determined as well.

Q: Why is it more difficult to detect dents with metal loss when the dent component is under 1% of the ID restriction?

Answer: When you start going below 1% with ID restrictions, there could be a number of anomalies that are the origin of that restriction — it may not be a dent. There may be nothing on the outside of the pipe. It may be within the mid-wall, like a blister or something that’s protruding into the ID. So, with that shallow of a restriction, there are various anomalies that you could be detecting, and it’s even more important to make that call correctly. Is it manufacturing related? Or is it a mechanical damage feature? This is one of the reasons why starting with UHR tools for clear, much higher resolution data, and then pairing the run results with an experienced analysis team, is so important. The combination of these two allow for the highest level of confidence to make the right call at this level of nuance.

Question: If a dent with metal loss is identified, and upon excavation a deformation is not observed, what should an NDE tech be testing for on the pipe?

Answer: If the NDE tech is not finding anything on the external surface and it looks like pristine pipe, the first thing they should check is the wall thickness of the pipe. More than likely, if they go out and do a dig for a deformation and nothing is found on the external surface, it is likely to be some kind of manufacturing flaw that is pushing metal into the ID of the pipe. You could have a lamination bursting to the surface that is migrated from the mid-wall into the ID of the pipe. It could be a blister on the pipe that’s protruded the ID of the pipe inwards. So, if they believe they’re on the right joint, they should be testing the wall thickness of the pipe. This is something that should be done even when you find a plain dent — they should measure the wall thickness within the dent to ensure there’s no internal flaw occurring at that location.

Question: How does a touching metal object affect the gouge determination?

Answer: Anything that adds additional metal affects the detection of volumetric loss in MFL, because now volumetric loss must consider all that additional metal that’s there. It will diminish any associated metal loss signal. A pipe support is a good example of a close metal object. It can be more difficult to detect, particularly the less detectable depth of metal loss that’s present. What I mean is that if the metal loss is very shallow to begin with, it may not be detected at all versus if you have a gouge that has substantial depth, it will be detected in the data but it will be diminished in what would be reported. A close metal object would be flagged for the operator when it is excavated, making this easier to evaluate. Sometimes that close metal object could be a foreign pipeline, could be something someone dropped on the pipe. There could be several things. But those things are discussed with the operator, who is made aware of that situation.