ASME Standards

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paresh_career001 Power-User Join Date: Oct 2008 Location: Gujarat, India Posts: 142	ASME Standards 04/27/2009 8:30 AM
	According to ASME SECTION VIII DIV.2 EDITION 2007, PART 7 it is stated that one can do UT in lieu of RT provided so and so condition is followed, but What are the benefits by implementing this? cost wise, time consumption by testing ... what are the factors to affect this? __________________ Paresh B. Gujarati
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Anonymous Poster	#1 Re: UT in lieu of RT as per VIII-2 Edition 2007 04/27/2009 10:51 AM
	What is UT? What is RT? Please define your acronyms.
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Anonymous Poster	#2 In reply to #1 Re: UT in lieu of RT as per VIII-2 Edition 2007 04/27/2009 9:24 PM
	Guest - if in the context of the question you do not understand the meaning of UT and RT then you will be unable to help the poster, so your question is redundant. For interest though - UT is Ultrasonic testing and RT is Radiographic testing. OP - this forum might help you http://www.ndt.net/wshop/forum/messages-1/1557.htm
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sb Guru Join Date: Mar 2007 Posts: 2550 Good Answers: 103	#3 Re: ASME Standards 04/27/2009 10:06 PM
	As the Guest #2 link has pointed out, there is some obvious advantages of RT over UT. However to understand you must be aware of the details of the two procedures. a) RT provides a permanant record unlike UT. b) Both the methods are sensitive to the orientation of the flaw. c) The UT can pick-up smaller flaws than RT subject to above (b) d) The effect of orientation can be negated more effectively in UT by selection of method and probes than in RT (which evidently can not be done from all the orientations. e) dead zones exist in UT f) UT as pointed in the link is totally dependant on the operator and his hand, eye co-ordination. Especially in small indications, he is likely to miss the peak. The preferances vary between expert to expert. I prefer UT over RT when the smaller indications matter and supplement with MPI. Once the back chipping/gouging and LPI is done and process parameters are properly maintained, joints rarely fail in either. RT is again what is insisted by the customers more from the proof angle. __________________ Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
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paresh_career001 Power-User Join Date: Oct 2008 Location: Gujarat, India Posts: 142	#4 In reply to #3 Re: ASME Standards 04/28/2009 12:23 AM
	thank you sir for your kind help.. I think that another advantage is RT takes lot of time for keeping whole vessel in RT enclosure... another is more hasardous ........ Last question is cost of the RT........for the same complete vessel to be examined by UT and RT, which method is more costier? __________________ Paresh B. Gujarati
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sb Guru Join Date: Mar 2007 Posts: 2550 Good Answers: 103	#5 In reply to #4 Re: ASME Standards 04/28/2009 12:28 AM
	That is simple. RT by any account. Just think about the cost of source , consumable (Film), developement, ... But again caution: UT is highly operator dependant (and we see a lot of them being manipulated- eg my vendor UT is OK, but my in house repeat UT finds defect- but not vice versa ) __________________ Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
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CT Participant Join Date: Jun 2011 Posts: 1	#6 In reply to #3 Re: ASME Standards 06/27/2011 10:42 PM
	Hello, I am looking for help regarding the interpretation of the first paragraph of the text below in italic (the text was copied from ASME Code Section VIII Div Appendix 12 Ultrasonic Examination of welds UT) 12-3 ACCEPTANCE-REJECTION STANDARDS Imperfections which produce a response greater than 20% of the reference level shall be investigated to the extent that the operator can determine the shape, identity, and location of all such imperfections and evaluate them in terms of the acceptance standards given in (a) and (b) below. (a) Indications characterized as cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length. (b) Other imperfections are unacceptable if the indications exceed the reference level amplitude and have lengths which exceed: (1) 1 ⁄ 4 in. (6 mm) for t up to 3 ⁄ 4 in. (19 mm); (2) 1 ⁄ 3 t for t from 3 ⁄ 4 in. to 2 1 ⁄ 4 in. (19 mm to 57 mm); (3) 3 ⁄ 4 in. (19 mm) for t over 2 1 ⁄ 4 in. (57 mm). The question is... What happend if the NDT inspector find an indication which does not reach 20% DAC (never reach) but according to his experience and analysing the location and form of the signal of the ultrasonic wave, he considers it as a crack, lack of penetration or lack of fusion. Shall he reject the indication and the weld repaired? Your help in this matter will be highly appreciated
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