Dr Jim Breakell is an independent corrosion control and mater ials consultant with a particular interest and expertise in mar ine cor rosion and its control, including for ALWC.
He was the principal author of CIRIA guidance Management of Accelerated Low Water Corrosion in steel maritime structures (C634).
Here, in the first of a two-part article for Port Technology International, Dr Breakell examines why ALWC is a problem, what needs to be done and summarises the more common types of repair techniques.
The problem
ALWC is a par ticularly agg ressive, localised cor rosion phenomenon that can occur on unprotected or inadequately protected steel, maritime structures.
It results in patches of accelerated metal wastage typically in the low water zone just above the lowest astronomical tide (LAT) or, on some structures, in the immersed zone.
ALWC is probably now the most likely and aggressive form of localised attack that can occur within these zones. Its consequence can be extensive, unbudgeted and costly remedial repair resulting in maintenance works at an unexpectedly early stage in the life of a structure and the potential for premature collapse of those structures badly affected by the problem.
The ICE Maritime Board has estimated that repair costs resulting from ALWC on structures in the UK alone will be in excess of £250 million to save assets with capital value in billions of pounds.
ALWC can be recognised by…
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