NDE for repair of base material

By Mangesh Date 08-27-2013 07:28

Can any 1 tell me what NDE technique is use for weld repair of base material(Plate SA516 Gr. 70) which is not cover the weld seams as per NBIC and ASME.
If i do RT then one of my friend tell me to do RT on only above 6mm depth welding, and below that only do LPT/MPT. Is it wright, if yes then how, which code tells this criteria.

By ozniek

Date 08-27-2013 14:18

Hi Mangesh

Generally if repairs are made to the base metal, then the requirements of the material specification needs to be met. (Assuming the defect was inherent in the material from the mill.) Most material specifications will give guidance on allowable weld repairs to the material, although ASTM A516 is not one. (In some instances, the material spec will not weld repairs.)

If the repair to the material is due to some damage being introduced during fabrication, then first see what the material specification asks for. If this does not give guidance, then you need to perform repairs and NDT based on the design conditions and the most likely defect that could be present after the repair. Mostly UT and surface (MPI; DPI) comes to mind. For some design conditions, repair may not be a tolerable answer, then you may have to cut out and replace.

Hope that helps.

Regards
Niekie

By Hollaway Date 08-27-2013 13:20 Edited 08-27-2013 13:49

What kinda of repair are you making? Are you just filling in an arc gouge or are you cutting a section out and replacing it? Need to know a little more information on what youre tryin to accomplish. I see its on a seam. Long seam or girth? Do you have any information on the original design code? (U1, u1A etc...) If its a repair on a weld that has been xrayed then it will need to be shot again after the repair is made. Is there a nameplate on the vessel if you dont have a U1? Are yall making a code repair and issuing a R-1?

By Mangesh Date 08-28-2013 04:44

Thank you for reply, Yes i m making a code repair(R-1), And repair is not on the weld seams, its on parent materials. I am not replacing a portion, just grinding and building a thickness by welding. What NDT shall follow as per ASME or NBIC.

By Hollaway Date 08-28-2013 12:27

Get with your AI and let him know what you have going on and see how he wants you to handle the NDE. Typically on this type of repair all you have to do is PT or MT the prep area and then again to the final. Since it isn't a full pen weld, you won't need to RT it. ASME Section VIII isn't going to be much help to you on this one, it will fall under NBIC and should be in that code book, try section 3.3.4.3 in NBIC Part 3. Make sure there are no customer Specs on the repair, sometimes the customer will have specs that exceed code that you have to follow. Does the vessel require any PWHT? Another question, is this the only repair you have on the vessel? Weld build up usually falls under a routine maintenance and doesnt require an R-1 (see NBIC Part 3 section 3.3.2)