The pressure hull of a submarine has many penetrations to allow for the ingress and egress of sea
water, fuel, lube oil and air. For the Collins Class submarines, specifically designed steel hull
forgings are installed in the hull to provide reinforcement for these penetrations. This paper presents
a case study of corrosion and repair of the hull forgings.
The original nickel plated design of the hull forgings suffered corrosion due to sea water attack and
subsequent dissimilar metal coupling. The corrosion resulted in metal loss which introduced a risk of
serious impact on the function of the forgings. Short-term repair of the forgings was implemented by
way of localized weld repair and selective brush plating of nickel. Simultaneously, investigations into
long term solutions were carried out.