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Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsMaterial Select...Material Select...Will changing exchanger type help to reduce SCC?Will changing exchanger type help to reduce SCC?
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3/25/2006 9:00 AM
 
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We are the manufacturer of Polycarbonate resins. In our dewatering section, reboiler for the dewatering column is a shell and tube heat exchanger. This exchanger is used for a heat exchange between 23% PC solution & almost pure Chlorobenzene vapors. The material of construction for this condenser is SS316L. PC solution is on tube side, while chlorobenzene vapors are on the shell side. Recently we observed leakage in the condenser tubes. It seems that the leakage in the tubes is due to Stress corrosion cracking. Although we have observed some pitting in SS316L in a drum where there is not any joints ,the exchanger is failed within one year of operation under same operating conditions. Thus we have arrived at a conclusion that the corrosion in exchanger is due to the residual stress in joints in exchanger e.g. near tube sheet. So we want to replace the exchanger with any another type e.g., plate type. Kindly suggest if we get any benefit due to fewer joints in new type of heat exchanger which can help us in reducing stress corrosion cracking in presence of corrosive environment. Request you to suggest the type of heat exchanger suitable to avoid stress corrosion cracking. Kindly suggest us the better material of construction if needed to reduce the corrosion rate. Regards, Shailesh
 
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3/26/2006 9:00 AM
 
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Shailesh For the service temp / concentration of cholrobenzene ( described by you on Mar 25 and ek_55 in the earlier mail - Mar 23 ) unalloyed Ti / Ta or alloyed Ti with Pd would give better service as MOC. 316 L will pit and also develop SCC in cholorobenzene at this service temperature. Your leakage and SCC problem may get solved with change of material to Ti heat exchanger even with this design. Not sure how many heat exchanger manufacturers are equipped to supply plate type Ti *unalloyed or alloyed with Ti-Pd". Plate type Ti heat exchanger design and fabrication would cost much more than conventional tube exchanger tubes and tube sheet. Trust this is of help to you. C.V.Srinivasan Nishi Engineers Pvt Ltd India Mar 26,2006 E-mail: nishi@vsnl.com >We are the manufacturer of Polycarbonate resins. In our >dewatering section, reboiler for the dewatering column is a >shell and tube heat exchanger. This exchanger is used for a >heat exchange between 23% PC solution & almost pure >Chlorobenzene vapors. The material of construction for this >condenser is SS316L. PC solution is on tube side, while >chlorobenzene vapors are on the shell side. Recently we >observed leakage in the condenser tubes. It seems that the >leakage in the tubes is due to Stress corrosion cracking. >Although we have observed some pitting in SS316L in a drum >where there is not any joints ,the exchanger is failed >within one year of operation under same operating >conditions. Thus we have arrived at a conclusion that the >corrosion in exchanger is due to the residual stress in >joints in exchanger e.g. near tube sheet. So we want to >replace the exchanger with any another type e.g., plate >type. Kindly suggest if we get any benefit due to fewer >joints in new type of heat exchanger which can help us in >reducing stress corrosion cracking in presence of corrosive >environment. >Request you to suggest the type of heat exchanger suitable >to avoid stress corrosion cracking. >Kindly suggest us the better material of construction if >needed to reduce the corrosion rate. >Regards, >Shailesh
 
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7/25/2007 9:00 AM
 
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you can try ss316 calorised. we can calorise tem
 
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HomeHomeDiscussionsDiscussionsMaterial Select...Material Select...Will changing exchanger type help to reduce SCC?Will changing exchanger type help to reduce SCC?


  

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