Page 372 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

350 CONSEQUENCES OF CORROSION

Figure 5.30 Hard deposits inside the tubes (20).

Figure 5.31 Deep pits inside the tube (20).

Contact between aluminum and metallic copper and/or copper-containing solu-
tions must be avoided at all times under any circumstances.
The effects of galvanic (dissimilar metal) corrosion and their consequences must
be made known to designers, architects, and engineers in other disciplines (14).

5.3.7.4.9 Corrosion in a Cooling Water System Cooling water tubes are used
extensively in industry. Corrosion of cooling water tubes or pipes is a common
phenomenon. The heat exchanger was opened to examine the extent of corrosion.
Heavy deposits were revealed inside the tubes (Fig. 5.30). Isolated but deep pits
were present under the hard deposits (Fig. 5.31).
The measured thickness of the tube, mechanical tests, chemical analysis, and etch-
ing showed the tubes to conform to the properties specified for SA179 tubes. Exam-
ination of cooling water side tubing showed mild pitting and a hard, sticky uniform
deposit inside the tube (Fig. 5.32).