Preheating & Radiography Test

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Afshin Participant Join Date: Jul 2011 Posts: 1	Preheating & Radiography Test 07/26/2011 2:51 AM
	Hi I work in fix equipment manufacturing in oil & gas industrial. Fix equipment include vessel & Tower. In the sheet uses in some vessels, thickness is 50 to 80 mm(5cm to 8 cm). In Appendix R in ASME Sec VIII Div 1, for carbon steel with P No.1, preheating for weld in thickness over 1 inch(25mm) is minimum 75˚ C and don't say how temperature during welding specifically. In WPS (Welding procedure specification) max inter pass temperature acc to ASME equal to 250˚ C. Nozzles and flange in this project, are self reinforcing(integral type) and max body thickness is 120 mm and nozzle size is 24 inch. My question is how many increase temperature in preheating and during welding for this project? Also for radiography test, which thickness over than 50mm, Result don't show all defect, and increase density of source (iridium 60 to cobalt 60) at reason many limitation is not applicable. If we use double wall film, we see all defect in weld (Crack, Slag, …)? What do we do for this problem? Material uses for this project is ASTM A516 Gr70N, and have HIC test and NACE MR0175/ISO15156 and radiography test is full for all weld.
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Whitephone Guru Join Date: Jan 2010 Location: Mineral wells Tx Posts: 630 Good Answers: 34	#1 Re: preheating & Radiography Test 07/26/2011 7:24 AM
	With Ir 192 or C0 60, there is no to much to see (Single flim, double film is the same) over 50mm. For these thickness we are using TOFD and MT for surface discontinuities. TOFD: according to ASME V Article 4 appendix N MT: according to ASME V article 7. Regards, WP
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ronclarke Guru Join Date: Nov 2010 Posts: 507 Good Answers: 3	#2 Re: Preheating & Radiography Test 07/27/2011 8:49 AM
	Also for radiography test, which thickness over than 50mm, Result don't show all defect, and increase density of source (iridium 60 to cobalt 60) at reason many limitation is not applicable. If we use double wall film, we see all defect in weld (Crack, Slag, …)? What do we do for this problem? Do a panoramic exposure using Ir192, i have never heard of IR 60? Co 60 will not give the best image due to its output spectra. Ron __________________ I went to Texas A&M, I am proud to be an Aggee. Proud to be an Aggey, Proud to be an Agie.............Proud to have gone to Texas A&M.
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mahesh_4754 Associate Join Date: Oct 2008 Location: mumbai, maharashtra, india Posts: 45 Good Answers: 3	#3 Re: Preheating & Radiography Test 07/27/2011 1:54 PM
	Dear Afshin, Please see the electrode you are using. Normally all the electrode manufacturers recommend the interpass temperetures on the electorde cover/box. Please follow these recommendations. As your material is SA516 Gr.70 (carbon content less than 0.3%), you can use preheat temperature as 10 degree C as given in the App-R and the interpass temperature can be checked with temperature sticks. As for radiography of the 50mm thk. weld seam, you have answered the question-you can use double wall film technique or else Cobalt60. you can also please check your radiography technique as RT with Iridium 192 is possible for 50mm to 80mm thick plate. hope this helps. Regards, Mahesh_4754
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