High Pressure Heat Exchanger Diaphragm Removal/Retrofit Using Double Tapered Pressure Seal

摘要

This conference paper describes the successful removal of a tube side cover plate diaphragm (gasket) from a high pressure heat exchanger. The diaphragm was replaced with a double- tapered, metal pressure seal. This seal has been utilized in multiple piping and off-shore applications throughout the world for several years; however, this was the first known application on a heat exchanger of this magnitude within a refinery. Using creative thinking and taking the initiative, a reoccurring reliability issue (diaphragm weld cracking and subsequent process leakage to atmosphere) was resolved, all during a turnaround window (an opportunity!). Modification of the cover plate to accept the double-tapered, metal pressure seal eliminated the need to re-install the metal diaphragm gasket, thereby saving 75% of the reassembly cost of the exchanger. Utilized in conjunction with mechanical multi-jack bolt tensioners, this innovative retrofit has eliminated a reoccurring costly problem (in both maintenance cost and loss of opportunity). This additional reliability coupled with the significant future cost savings from less downtime justified the retrofit - not including the cost savings foreseen by preventing unplanned outages from the exchanger. The success of the first application led to the successful retrofit of a second exchanger. Currently planning is underway to retrofit the remaining 12 high pressure, critical service exchangers. This will occur during the next two turnarounds (2007 and 2010). It is anticipated that this modification could eventually change the way refiners will specify how high pressure heat exchangers in hydro cracking services are designed and constructed.