Hi Greetings. We have been facing frequent failures in Floating Head Joint of Split Ring type Shell and Tube Heat Exchangers. Following information would give further insight. 1. Exchanger AES-H( Vacuum Residue on T/S - PASSES:02, and Crude on S/S PASSES: 01) in Crude distillation Unit of Refinery. 2. Data (Float head cover SA 240 GR 316L / BOLTS: OPERATING PRESSURES 32 / 27 BAR, TEMP OUTLET: VR-265 AND CRUDE 258) 3. Main observation is loosening of bolts on top section of floating head predominently despite proper selection of gaskets and manual tightening methods. 4. tried un-successfully various alternatives like use of B16 bolts with locknuts, higher torquing of bolts etc 5. failure pattern repeates in all exchangers. 6. Process up sets any majority cases had been noticed prior to exchanger failure. upset of process units is normal and leakage is abnormal. ANY FURTHER INFORMATION WHEN REQUIRED CAN BE GIVEN, EXPECTING UR VIEWS REGARDS, KUSHA

our Normal practice is, when ever any exchanger reported leaking, first to do tube test, then shell test and again tube test after attending to respective problems during each test. Delta Temp across ( between shell outlet and tube outlet) is around 20- 25 deg C anyfurther information please feel free to ask thanks

Kusakumar Test procedure for gasket or tube to tube sheet joint leak - outlined by Luis - is OK. Did you check if thegasket is adequately designed for D.P in case of upset conditions. Since you have a problem of abnormal leak, possibility of gasket design for Differntial Pressure may have to be examined critically. Other aspect is the angle of split ring gasket seating in the groove and if there is a slight mismatch in split ring seating aangle then this problem will get pronounced. Diff temperature in your case is not much to affect this split ring gasket material. Diff Pressure could contribute to leaks during upset condtiions. Trust this helps you to study further. C.V.Srinivasan Nishi Engineers Pvt Ltd India Sept 29,2006 E-mail: nishi@vsnl.com >The usual practice to test an AES exchanger is: > > >1%C2º remove channel, remove shall cover, remove floating head >cover > >2%C2º Mount fixed tube sheet test ring, mount floating tube >sheet test ring > >3%C2º Hydrostatic test shell to check for leaks on tube >rolling expansions of both tube sheets > >4%C2º Remove test rings > >5%C2º Mount channel, channel cover and floating head > >6%C2º Hydrostatic test tube side to check for leaks on >floating head gaskets, channel/fix tube sheet gaskets and >channel cover gasket > >7%C2º Mount shell cover > >8%C2º Finally hydrostatic test shell side to check for leaks >on cover shell gaskets > >If you usual do so I see no reasons for your problem