Radiographic examination of gauge pipe

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Does anyone see any concerns with the requirement to perform radiographic examination on thin-walled pipe (10 gauge, 11 gauge and 14 gauge) with the acceptance criteria of ASME B31.3 (category D)?  THANKS.
Reply:My question is how the hell did they design piping that thin for 2500 class or severe cyclic conditions?  Obviously on thin material your source strength is going to factor into play.  Of course you could always go UT in lieu of RT.
Reply:UT with plate wave would check the entire thickness of something that thin.  It would likely be cheaper also.Proud to be a UNION worker.  Better pay, better benefits, better work environment.  UA Unions = working for the working class!!
Reply:The issue is not in the examination method.  The problem is we have not been very successful in meeting the standard.  Because the pipe wall is so thin, and the pipe is almost always not perfectly round, we've had alignment issues.  I wonder what is the average effectiveness (meeting the acceptance criteria fo ASME B31.3 via radiography) of welding thin-walled pipe.  Has anyone x-rayed welding on thin-walled pipe?  How successful were your results?
Reply:What sort of diameters are you working with?  What seems to be the primary cause of rejection?  What's the material in question?
Reply:Nancy,I've seen thin wall(sch 10) stainless pipe, ranging in diameters from 2" to 12" TIG welded and routinely pass X-ray inspection.  The larger diameter pipes would have wall thicknesses in the range you're describing.  This was for compressed air, chilled water, and low pressure lube oil piping systems.Can you share more details about the welding procedure, the weld joint prep, the nature of the defects that are observed in the radiographs?  You mentioned alignment concerns with the joints and out-of-round observed in the pipe...Are you seeing lack of fusion or some other discontinuity in the radiographs?  Or is heat distortion causing the joints to warp, so that you're failing to meet some geometric constraint?Maybe I or somebody else here can spot some inconsistency that's the root of your problem... Originally Posted by NancyThe issue is not in the examination method.  The problem is we have not been very successful in meeting the standard.  Because the pipe wall is so thin, and the pipe is almost always not perfectly round, we've had alignment issues.  I wonder what is the average effectiveness (meeting the acceptance criteria fo ASME B31.3 via radiography) of welding thin-walled pipe.  Has anyone x-rayed welding on thin-walled pipe?  How successful were your results?
Reply:The alignment issue is just a case of the right tool for the job, and the right way to use it.I'd rather be hunting........USE ENOUGH HEAT.......Drifting around Aussie welding more pipe up, for something different.....wanting to get home.
Reply:Nancy, if the suggestions above don't lead you to the source of your problem, you may want to consider the skill level of your welders.  I'm not trying to point a finger, but many places hire the cheapest welders they can get, then they can't do the job expected.  For example, if you're in my area and you pay $15, you will only get $12/hr guys to grace your doorstep.  If you choose the best of them, you may still have problems getting xray quality welding done.Proud to be a UNION worker.  Better pay, better benefits, better work environment.  UA Unions = working for the working class!!
Reply:Well there's a thing Engloid.  But how do you get people (read boss type) to understand?I'd rather be hunting........USE ENOUGH HEAT.......Drifting around Aussie welding more pipe up, for something different.....wanting to get home.
Reply:Nancy,B31.3 ( Category D) does not require radiography unless it is a customer requirement. Visual inspection only as per 341.4.2.Over the years I have welded and then (when I moved into inspection) radiographed literally hundreds of Sch 10 welds of various sizes with absolutely no problems at all. The secret is in having good pipefitters and good clamps. It is very easy with the thin walled pipes to actually "squeeze" an out of round pipe back into shape to counter misalignment. That is where a good pipefitter is worth his weight in gold. Even if there is a slight difference in total circumference he will be able to spread the misalignment evenly so it is still within tolerance (and still weldable) instead of having unacceptable bulges that are unweldable.Hope you understand my attempt at explanation,Regards,Ballbearing
Reply:I believe that X-ray (better than gamma) would be the most appropriate form of testing for this connection.
Reply:Originally Posted by qaqcI believe that X-ray (better than gamma) would be the most appropriate form of testing for this connection.
Reply:Gamma rays come from enriched elements like cobalt-60 and iridium-192. X-rays are produced electrically. They are more sensitive and better suited for thin materials"Religion is regarded by the common people as true, by the wise as false, and by the rulers as useful." -- Seneca the Younger
Reply:http://www.windows.ucar.edu/tour/lin...m/em_xray.htmlI did say that gamma is xray, and I meant that xray is gamma, which I now understand is incorrect.I guess that's why the correct term is to say that it is RT, not xray...because it is checked with radiation, but not the electronically produced "xray."  Correct?Proud to be a UNION worker.  Better pay, better benefits, better work environment.  UA Unions = working for the working class!!
Reply:Engloid,RT (Radiographic Testing) can be performed with either gamma or x-ray.With gamma it is a radioactive isotope so natural radiation is always being produced whereas the radiation from an x-ray set is produced by turning the set on or off like a light switch.QAQC,You are correct that x-ray would be the best procedure on thin walled pipe, however if access is difficult gamma with ultra fine grain film is quite acceptable.Cheers,BB
Reply:Originally Posted by BallbearingQAQC,You are correct that x-ray would be the best procedure on thin walled pipe, however if access is difficult gamma with ultra fine grain film is quite acceptable.Cheers,BB
Reply:QAQC,Not sure which part of the world you are based but there would not be that many NDT companies with a selenium-75 source where I come from.We have never had any problems achieving required sensitivity and density with Ir192 using AGFA D4 on Sch 10 piping.As stated earlier I agree with the fact that X-ray is better than gamma on thin walled material,Regards,Ballbearing