Question

Which parts of the internal structure of a ship are most liable to corrosion and why

How can the effect of corrosion be reduced.

GENERAL CARGO SHIP.

Areas most susceptible are the lower end of hold frames, open bilges, 'tween deck connections to shell and bulkheads, double bottom    floor    plates    around notches  for longitudinal, inner surfaces of tank top and bottom shell.

BULK CARRIER.

Areas most susceptible are the inner surfaces of lower and upper hopper tanks, welded seams in transverse webs, notches and drain holes.

TANKER.

Areas most susceptible are the upper parts of bulkheads, longitudinal and transverse webs in way of notches and drain holes at the bottom of the tank, welded scams especially in cross ties.

Maintenance includes cleaning and re-coating with pits filled or welded:  

Serious corrosion over an extensive area would need plate renewal.