recommendations for spot painting, repainting, or
more frequent inspection. The frequency of repainting
can be determined by periodic inspection of all
coatings. It is important to check on a systematic basis
so that painting can be scheduled in advance, at a time
when the coating is thin enough, yet has not degraded
to the point of disintegration. Thus little surface
preparation will be required, and only one or two coats
of paint may be necessary.
Stages of Paint Deterioration
Paints which are exposed outdoors normally
proceed through two stages of deterioration; generally,
a change in appearance followed by a gradual
degradation. If repainting is not done in time,
disintegration of the paint then takes place followed
ultimately by deterioration of the substrate (basic
surface). Interior coatings generally change slowly in
appearance with time but do not usually degrade to any
significant extent otherwise.
The first stage of deterioration shows up as a
change in appearance of the coating with no significant
effect on its protective qualities. This change in
appearance may result from soiling, fading, or
flattening, depending on the type and color of the paint
used and the conditions of exposure.
The second stage of normal deterioration occurs
after continued exposure. The coating begins to break
down, first at the surface, then, unless repainted,
gradually through the coating and down to the
substrate. There are two types of degradation that may
take placeeither chalking or checking and
crackingthe degree of either depends on the type of
paint and the severity of exposure. When large areas
of substrate become exposed, the coating has reached
the point of complete deterioration and is in a state of
neglect. Such surfaces require extensive and difficult
preparation before repainting. All of the old coating
may have to be removed for you to ensure that it does
not create problems by continuing to lose adhesion,
taking the new coating with it. Furthermore, complete
priming of the exposed substrate will also be required,
thus adding to cost and time. Continued neglect may
also lead to deterioration of the structure, resulting in
expensive repairs in addition to paint costs.
It is assumed that, through study and experience,
you are familiar with the defects resulting from the
various stages of deterioration mentioned above and
can readily identify them. Therefore, the defects are
not described here.
As with buildings, the maintenance inspection of
waterfront structures should be designed to include the
following: (1) the prompt detection of deficiencies or
damages and (2) the expeditious performance of
repairs, consistent with requirements, in an
economical and workmanlike manner.
Deterioration of waterfront structures is caused by
the destructive forces to which they are exposed, such
as the following:
Attack by marine organisms
Rust, corrosion, and decay
Mechanical damage, including the impact and
pressure of ships, and the abrasive action of sand
Wave action and erosion
To determine the extent of maintenance and repair
work required, an inspection should be made annually
of all basic structures (piers, wharves, quay walls,
bulkheads, and retaining walls) and semiannually for
fenders and movable equipment, such as brows and
camels. More frequent inspections than those
specified may be necessary under certain
circumstances, such as tidal waves, high tides,
earthquakes, and action by destructive forces of
nature. Inspections may be made from the structures,
from a boat or afloat, or from below the waterline by
divers. Cameras are often used in visual inspections.
Some of the major defects that can be seen by
visual inspection are as follows:
Spans, cracks, and breaks in concrete work.
Rusting of structural steel and exposed
reinforcingsteel in concrete.
Decay in wood.
Mechanical damage, resulting in broken or
Damage by wave action and water erosion,
including thewashing out of fill through
Shrinkage of timbers around bolts and cracks
aroundloose bolts that allow water to enter.
These conditions areusually found in pier curb
rails, stringers, wales, pile caps, and other
members above the tidal range.
Deterioration of decking.