Page 373 - Challenges in Corrosion Costs Causes Consequences and Control(2015)
P. 373
CORROSION DAMAGE, DEFECTS, AND FAILURES 351
Figure 5.32 Hard deposit inside GE 16 tube (20).
Figure 5.33 Perforated tube (20).
At some points, the deposit was in the form of lumps. Deep pits were also observed
below the solid deposits and perforation below the deposit in one case (Fig. 5.33).
Measurement of the thickness of the tubes showed no general thinning.
Flow measurements showed flow rates lower than expected, and backwashing was
observed. The backwash contained brownish siliceous matter and other solid impuri-
ties. All three heat exchangers had silt and dirt deposits and partially plugged tubes.
The tube ends were corroded and thinned down. Perforation of the tubes originated
from inside (cooling water side). Pitting appeared to be underdeposit corrosion.
A commercial cooling water program during start-up and stabilization of the cool-
ing water tower after major repairs is likely to avoid the adverse results (27).
5.3.7.4.10 Pitting Corrosion of 90/10 Cupronickel Chiller Tubes The cupronickel
tubes in a water chiller suffered from severe corrosion damage during their relatively
short service life (28). Figure 5.34 shows the top section of the condenser where a
