05:35 Nov-08-2002 JALight Consultant, Corrosion Prevention Deepwater Corrosion Services Inc., USA, Joined Jul 2002 12
Re: Scan methods : : 1. Do you need to remove the coating when doing B or C scan? . : NO. In B-Scan you can use the multiple echo method : . : : 2. If the coating is not removed how accurate is the result? . : Same as an other. : . : : 3. If there is sand or any other product with a different impedance from the steel, is it possible to detect such based on the different signals coming out? : . . : The material has to be bonded to the steel before there is an impedance change. : : Thanks : .For questions 1 & 2, the type of instrument that you use is important as not all B or C Scan instruments have the multi-echo option. If multi-echo is not available, the coating will affect the data but ususally only slightly depending on the type of coating. We overcame this problem by "Proving Up" any significant indications with a multi-echo A-Scan unit. This was a concern of our client and the way we all decided to overcome it. Newer B and C Scan instruments should offer the multi-echofunction however. Amount of .