Bob, The question you ask is difficult to answer simply...Performance of the condenser depends on many variables. i assume that the question you are really asking is --- How much will the performance of my unit be degraded by swapping the tubing with 316 stainless steel ? How much back pressure can you tollerate and still have the steam turbine perform ? Your replacement of admiralty condenser tubes with another material has been done many times before by various utility firms. New steam surface condensers that are typically designed for cooling tower water use types 304/316 stainless steel. The required condenser surface area is somewhat larger ( about 15-25% as I recall) than would be required for an admiralty metal design. In the 1980's, I worked on the replacement of steam condenser modules and feedwater heaters in a nuclear power plant in Maine. After extensive studies, the utility decided to replace the feedwater heater tubing with type 439 Stainless steel and replace the condenser tubing with AL6XN ( seawater was used for cooling) I suggest that you contact some of the steam surface condesnser vendors and ask about a re-rating calculation of your particular unit with various material options A good place to start would be the folks at YUBA, in Oklahoma www.yuba.com I can give you other suggestions, but you must tell us more about the installation, particularly the type of cooling water going through the condenser. my opinion only....... MJCronin

Many thanks for your nice reply MJCronin, Our set is an extraction-pass-out condensing set 14 MVA 2800 k Pa 415 Deg C and a maximum of 20t/hr of steam may be condensed . The cooling water used is river water @ 22 Deg C. Thks. Bob