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Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsOil Refinery Co...Oil Refinery Co...Cupro Nickel Tube FailureCupro Nickel Tube Failure
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2/13/2010 9:00 AM
 
Hi experts We had a typical failure in one our condenser in Cryogenic plant. Tube Side - Sea water from cooling tower. We found of tube found leaky in pneumatic test.We pulled out the tube found a localized pin hole leak in the tube.Leaky portion appear little blackish.We have not yet split open the tubes. Tube Metallurgy : 90/10 Cu-Ni As any one have faced this type of localized failure in tubes in CU-Ni with sea water? Please throw some light into this matter Regards
 
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2/13/2010 9:00 AM
 
Please specify the shell side fluid and indicate the nature of scales(internal or external).
 
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2/14/2010 9:00 AM
 
Dear Mr Krish Shell Side : Propylene.There was no scales observed both internally and externally.The exchanger was commissioned only 3 months back. Regards
 
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2/15/2010 9:00 AM
 
It is advisable to to spilt open the tube at failure location to find out the exact cause of failure. The selected tube material is an ideal choice for thes service mentioned. The failure in Cu-Ni tubes in sea water service could be due to any of the following reasons, 1)Inadequate water treatment which may increase the level of Oxygen in the water 2)MIC related corrosion in absence of propoer Corrosion Inhibitor 3)Usage of brakasih water
 
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2/17/2010 9:00 AM
 
Inspector 1978 Cu Ni tubes - although quite resistant to sea water treatment in heat exchangers (marine, petro chemicals, refineries using sea water as coolant) have had varied successes and failures by users. You have to do a failure analysis including deposit analysis, replica metallography at the cut open tube at the failed area (i.e, on the tube removed from service with pin hole leaks). It would throw some insight definitely. Sea water cooling on tube side is well known to accelerate failure or initiate failures like pin hole leaks due to: starts with micro-bio fouling (with variation in temp, velocity,localized oxygen depletion, crystal nucleation site) and this could result in local starvation due to underside deposits or fresh nucleus sites for higher surface temp and increase in velocity or less sea water fluid flow to cause a pin hole leak. The fact that in 3 months service the tube had failed (you have experienced failure) for a 90/10 Cu-Ni tube (normally this should not happen in such short service life) could also point for you to look from the supply angle. Cu Ni tube supply (if specified and ordered in semi hard / hard condition instead of annealed) or if ordered as ERW Cu Ni tube to save costing could also contribute to failures than anticipated life streams. Please examine the failed tube and also the plant operating log history in 3 months for this failure - Is it a freak occurrence or one of a sporadic failure or could this lead to more recurrent failures in future? Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Feb 18, 2010 E-mail: nishi@vsnl.com >Hi experts > >We had a typical failure in one our condenser in Cryogenic >plant. > >Tube Side - Sea water from cooling tower. > >We found of tube found leaky in pneumatic test.We pulled out >the tube found a localized pin hole leak in the tube.Leaky >portion appear little blackish.We have not yet split open >the tubes. > >Tube Metallurgy : 90/10 Cu-Ni > >As any one have faced this type of localized failure in >tubes in CU-Ni with sea water? > >Please throw some light into this matter > >Regards
 
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HomeHomeDiscussionsDiscussionsOil Refinery Co...Oil Refinery Co...Cupro Nickel Tube FailureCupro Nickel Tube Failure


  

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