I would like to give my thanks to you by the excellent site you have and also by such detailed information. Leakage from after cooler of air compressor in our power plant led us to shut down the compressor for several times .Visual inspection revealed severe corrosion of copper alloy tubes (SB-111). Corrosion was as a deep pin hole from inside of the tubes in the area near the outlet tube sheet.Air is in the tube side and water in the shell side.The suction of the compressor are near the place that atmosphere is contaminated by ammonia gas.Is it possible that ammonia gas comming with air into commpressor be the cause of this failure.If yes how it can make this type of corrosion. Any comments would be highly appreciated. m.m.jorat

Air Compressor - After Cooler Tube Failure at the outer tube sheet end Corrosion of tube (air inside) given in describing the problem informs deep pin holes were seen from inside to outside in the failed after cooler tube close or nearer to the outer tube sheet. Ammonia gas entering the after cooler tubes was suspected. Ammonia gas - if air compressor sucks - may give problems first to the First Stage Suction - Ist stage compressor blades If compressor is centrifugal) or suction valves (if compressor is reciprocating) If it is reciprocating compressor, suction valve will flutter and suction temperature and suction pressure will increase. Also ammonia gas will generate enough vapor pressure and temperature that it will be difficult to operate (at the inlet of first stage). This will give problems of maintaining pressure and temperature at the first stage itself. Before failure is experienced in only after cooler tubes - SB 111- failures may be experienced in inter cooler and also at the first and second stges of air compressor. Description given ddid not elaborate about the type of compressor (reciprocating or centrifugal). Problems will also be experiecned in inter and after cooler separators in addition to the first stage /second stage compressor valves or compressor blades. For the failure of SB 111 - after cooler tubes - i guess the cause could be due to other factors - not diagnozed fully. Carry over of ammonia upto the second stage to affect only the after cooler tube at the outer end may happen but before that all intermediate stage equipment and compressor valves will be affected. Please look at from this possibility also. A thorough diagnosis and analysis is needed instead of guessing. C.V.Srinivasan Nishi Engineers Pvt Ltd Chennai India July 13 E-mail:nishi@vsnl.com >Masoud: > >It is indeed possible that, if ammonia vapors are condensing >on the tube side of the exchanger, an aqueous ammonia >solution is responsible for corrosion of the copper >exchanger tubes. > >Hope this helps! > > >David Hendrix >The Hendrix Group Inc.