Page 626 - Corrosion Engineering Principles and Practice

588 C h a p t e r 1 4 P r o t e c t i v e C o a t i n g s 589

Engineer/specifier

Manufacturer

Owner

Contractor/applicator
Inspection

FIGURE 14.1 Breakdown of the responsibilities associated with 84 coating
failures thoroughly investigated.

Prefabrication decisions and posterection corrections include
elimination of sharp corners and hard to reach places, adoption of
designs that will not collect or hold water or debris, provision for
drainage of recessed zones, smoothing of rough surfaces and rounding
of corners, removal of weld splatter, avoidance of skip welding, and
caulking of crevices [4].
Tubular or box shapes should be used whenever possible to
minimize edges and inside corners. If possible, the metallic
materials selected should have the best resistance to corrosive
attack or be alloyed to enhance coatings performance. A particular
attention to design should be made to minimize the dwelling time
of atmospheric condensation and provide special attention to
surfaces shaded from the sun [5]. Large enclosed spaces that have
not been totally sealed, such as the insides of box girders, should be
coated, or ventilated, with fans if necessary. Decisions on coatings
should not be left to the casual attention of inexperienced personnel.
It is quite clear that
1. Decisions concerning effective protective coatings can be
made properly only by experienced personnel.
2. The economic consequences of poor coating practices can be
disastrous.
3. The number of coating materials available necessitates careful
study if a proper material is to be selected.
4. Proper surface preparation is a prime economic factor for
coatings in any environment.