7. Coating Failures

7.4 Types of Failures

3. Design Related Failures

(d) Design of nuts and bolts:

Extra precautions need to be taken in riveted and bolted joints as they are subject to corrosion. Because of crevices, differential aeration cells and bimetallic contacts are created unless appropriate precautions are taken. Figure below shows that the design can be improved by insulation and welding. Nuts present a genuine difficulty because of their geometry.

Insulating unions

Flange insulation kit.

(e) Faying surfaces

Application of zinc coating on the faying surfaces prior to joining them by bolting or riveting is a good method of protecting the inner surface.

Link seals for casing and wall sleeves.