‘Open Forum - Question and Answers’ session at the end of the Presentation by Andreas Boenisch of Innospection
Yeah thank you, Glenn Wilson - Hess. Just a quick one, you talk about defect identification. In that would you be able to tell me what the wall thickness or the thickness of the material that was remaining?
Andreas Boenisch (Presenter) – Innospection. Eddy current as such is not an absolute technique so it is not when you compare it to ultrasonic you get a remaining wall thickness analyse or display. Eddy current - what we do here we set it in comparison to a calibration sample and then we say we have here a wall loss in percentage of lets say 20 to 30% in typically in 10% steps.
Glenn Wilson - Hess. So if I gave you a virgin pipe and gave you a defect pipe or a pipe that had been exposed to corrosion you’d be able to tell me the loss?
Andreas Boenisch (Presenter) – Innospection. We tell you then here is corroded here between 10 and 20 or between 30 and 40% yes.
Glenn Wilson - Hess. Ok thank you.
Martin Wall – ESR Technology. A couple of questions. You were talking about the need in the next stage to try and identify the location of the defects within the different armoured layers. How would you do that and what sort of methods would you use?
Andreas Boenisch (Presenter) – Innospection. Well as you have seen with the principal I displayed we’re using DC magnetic field lines and we’re using eddy current field lines. By setting the strength of either field line you reduce the field line strength further up and up and up so you’re not, from a certain, we start with a full penetration so that we see the defect through all the layers and at that stage then you can reduce the field strength so that you’re not seeing anything in a zeta wire anymore than would say than you see it, is a indication still there then its in one of the outer armoured layers then you would reduce it further and you can see it was in that armoured layer and that armoured layer so you change the magnetic field strength. You change the eddy current frequencies.