| Piled
structures have always been designed with ‘corrosion
allowance’ on top of the design thickness required
for structural stability as constructed. This allowance
for the full length of the piles has generally considered
only ‘normal marine corrosion’ (at its maximum
in the splash zone and at low water). The greatly increased
thickness required to leave structural stability after
accelerated corrosion would make this practice uneconomic.
However, the use of additional plate thickness at specific
levels would be more practical, could be factory applied
and would not impede driving during construction.
Similarly the use of plates as a repair method is equally
useful See image 1,
particularly if loss of steel thickness has depleted
the design thickness, or even holed the steel when physical
repair is essential.
Repairs can be specifically tailored to meet the preferential
attack found See image
2.
See:
On sheet piles plates can be welded to the clutch area
being the most robust section of the pile, and the area
shown to be the least likely to be attacked preferentially
See image 3.
Clutch and preferential attack being in different positions
for ‘Zed’ and ‘U’ piles, effective
repairs may also be different, including the use of
concrete to block holes and protect inpan on Frodingham
piles See image 4.
On ‘U’ piles the technique can be used
for ‘in’ as well as ‘out’ pans
See image 5.
To make a guaranteed high quality weld, with Non Destructive
Testing (NDT) being practical, limpet dams offer the
best below water solution. This photo of repair plates
has been taken below water level in such a dam, allowing
full client inspection and giving full confidence.
Effective underwater welding is now possible and may
offer excellent emergency repairs to holes and temporary
fixings for access, if visibility is sufficient.
Plate repairs may be carried out in conjunction with
Paint Coatings.
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