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Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsGeneral Corrosi...General Corrosi...Corrosion of H2 comp. 2nd stage intercoolerCorrosion of H2 comp. 2nd stage intercooler
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9/23/2008 9:00 AM
 
Ashraf Saad KNPC-MAA Dear experts we have subject cooler having H2 in tube side and cooling water in shell side with CS metallurgy.We retube the cooler at 6 months frequency as result of water side corrosion .we beleive the this because of the rong design of using water in shell side.any suggestion ? any informations if the codes discourage this design Thank U
 
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10/22/2008 9:00 AM
 
As you mentioned due to routing of cooling water at shell, the tube is failing in every 6 months.This is mainly due to accumulation of cooling water scales in baffle location and dead zone causing crevice /under deposit corrosion. As you already suggested, routing cooling water in the tube side will reduce the frequency of retubing. However,if the cooling water treatment is not good then the life expectancy of tube is less. If service temperature permits, you can think of coating inside the shell to avoid deposition of scales. As an alternate you can think of using super duper SS with high PREN to avoid crevice/pitting corrosion. regards,
 
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10/22/2008 9:00 AM
 
Ashraf Saad Shell side cooling with cooling water and hydrogen in tube side is not a un-common usage. It is a common usage as per TEMA / ASME code practices. Many plants use this without any major problem where Hydrogen is in tube side-at low temp < 100 deg cent (especially in refrigeration system in a process chemical plant) with shell side cooling water. If cooling water chemistry changes on the shell side due to low flow or turbidity or with high scales in the cooling water treatment or scale deposit due to heat transfer not effective (biological or under deposit corrosion is a problem identified in your case), you can think of Alonized tubes to over come this problem. As Krish had suggested, there is a possibility of crevice attack at the baffle suppport to tube due to higher clearances than design needs per TEMA then tube can corrode at the crevice / under deposit corrosion. In some plants, vibration and chattering due to excess clearance between baffle support and tube causes tube failure (need not be due to cooling water chemistry variations). After a thorough analysis on the cause of failure, you can modify or change to a coated or Alonized tubes to overcome this problem. Basically, shell side cooling water and tube side hydrogen is common as per code designs. Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd Oct 23, 2008 E-mail: nishi@vsnl.com >Ashraf Saad >KNPC-MAA >Dear experts >we have subject cooler having H2 in tube side and cooling >water in shell side with CS metallurgy.We retube the cooler >at 6 months frequency as result of water side corrosion .we >beleive the this because of the rong design of using water >in shell side.any suggestion ? any informations if the codes >discourage this design > >Thank U
 
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