Hollow box section steel is susceptible to corrosion from the inside when water is allowed to get in from defects and modifications.
This is particularly important in load-bearing structures.
Structural box section steelwork can corrode from the inside and can’t be seen until it’s too late.
In this instance, the internal corrosion in the structure had not been identified by previous inspections until the base metal was completely corroded, exposing holes in the members.
Does your inspection type and frequency match corrosion mechanisms?
Be aware of the potential for water ingress from modifications e.g. unsealed holes.
Report any signs of damage to your supervisor.