[MW:2085] Re: No Defect Revealed procedure ?

Dear Prem, During RT you need to consider the exposure for the remaining thickness only i.e 35 -15 = 20 mm. This will give you the radiograph which you can interpret at least to find out the slag. Another thing shall be considered is make the grove wider instead of sharp V grove (after back gouge/grind make a "U" (nearly flat at the bottom) which will again help to get the good radiograph. Another method is UT... but again the UT operator shall be skill to find out whether the echo is coming from the sharp edge of the grove or from the slag...and echo pattern also will help to identify the slag or sharp edge of grove.. I am not the (hands on) NDT expert but this is what we discuss and do generally when we have problems..like you have. Other NDT experts are there around the group and I am sure they will give better views on this...I also will prefer to learn the better techniques available and followed..         CK --- On Sat, 2/5/09, PREM SHANKARDUTT NAUTIYAL <prem_nautiyal@rediffmail.com> wrote: From: PREM SHANKARDUTT NAUTIYAL <prem_nautiyal@rediffmail.com> Subject: [MW:2080] No Defect Revealed procedure ? To: materials-welding@googlegroups.com Date: Saturday, 2 May, 2009, 8:47 PM Hi Friends Can anyone guide me about how to carry out NDR (No defect Revealed)procedure for Repair Welding. The matter is: We have a circ. seam of two shells ,1m OD,35mm thick.Material Alloy Steel (marine steel).Double V butt joint welded by SMAW. We landed up in a slag inclusion after RT. Now by UT we found out the depth of slag i.e 10mm from top and length 100mm. So we grinded upto a depth of 14mm from top. Then we conducted RT for ensuring No Defect was Revealed or Present. But surprisingly the RT film was just dark with lot of density variations and we could not confirm whether the defect (slag) was removed or not as it was difficult to interpret the radiograph. Now can anyone help me out : How do we ensure by Radiography that the defect is removed after grinding. i.e how do we conduct Radiography of such partially grinded areas. Also the material can be repaired only twice, hence i want to confirm that the slag at depth of 10mm is completely removed before welding. Are there any other NDT method for doing NDR for repairing welds ? Regards Prem S Nautiyal Cell:9820313278 PREM S NAUTIYAL CELL : 9820313278

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