Posted by George Larose on October 30, 2001 at 16:41:19:
In Reply to: Thinning of economizer coils posted by S. Sen on October 29, 2001 at 08:15:16:
: What could be the reason of general thinning of economizer coils when no external corrosion is observed?
Check your feedwater pH. Low pH (Less than 8.3 if there is dissolved carbon dioxide in the feedwater, less than about pH 6.0 if not) will cause general metal removal from ferrous materials. You may be contaminating your condensate return(s) with process material. If pH and its overall history are good (above pH 8.3, preferably 9.0), look to the economizer coil material. Is it compatible to the intended use? Is there a pattern to the thinning, or is it general, homogeneous? Are there any suspended solids of any size in the fluid stream? Verify relative rate of corrosion by observing volume of corrosion product material in bottom drum areas, blowdown tanks, etc.