Full-Length Sleeving for Process Heat Exchanger Tubes
By Stanley Yokell MGT Inc. |
As heat exchangers age, their tube thickness decreases because of erosion, corrosion or a combination of both. Installing thin sleeves in tubes in which the tube walls have become so thin that failure is imminent is a maintenance technique useful for extending heat exchanger life.
One should consider sleeving when: (1) it would be very costly to replace aged exchangers because of the installation position or the shutdown time required to remove the existing one and install a replacement exchanger or tube bundle; (2) replacement tubing delivery is so long that unscheduled shutdowns for plugging failed tubes become so frequent as to cause serious loss of production; and (3) some decrease in the effective heat transfer surface is acceptable.
The power generation industry has long used sleeving of tubular heat exchangers to extend the life of steam surface condensers and closed feedwater heaters. The thermal- and pressure-loss effects of sleeving closed feedwater heaters has been discussed in Ref. 1, which provides equations for calculating the effects of sleeving with short sleeves, sleeving with full-length sleeves and in either case sleeving only some tubes (partial sleeving). Spreadsheets for performing such…