Some clients are not really aware of how serious/dangerous damaged condition are for the container under-structure, maybe just because of the underside structure is seldom to be exposed to have an inspection. In fact, underside structural members are easily damaged by various lifting operation. These photos show the damaged cross-members and tyne-side, which are resulted from the tough improper forklift operation. This type damage is hard to see, and does weaken the flooring strength integrity. If no repair occurs at the first place, it would cause much more expensive repair cost soon.
This box got an in-service inspection somewhere five months ago, and had a CSC updated.
It is believed that the corner casting bottom aperture has been worn-out then, apparently the client ignored such worn-out damage to put it for use continuously. From stage 1 photo, just half percentage thickness remains after worn-out. Then, it could cause stress cracking due to remaining wall thickness collapsed as shown in stage 2 photo. Finally, whole material would be gone (stage 3) and an impact-like breakage/breach happens. It is extremely dangerous condition during the transportation.
Photos are taken in a 48ft container, it is clear to see that, when the structural cracking just happens it always starts from hairline cracking at the top or bottom joint of crossmember/side rail, at this stage, many clients will say put them as NO ACTION TAKEN, then the cracking would extending throughout the entire web section (see stage 3 photos), finally completely separated each other.
In this typical case, the damage is definitely NOT resulted from external impact force, a structural stress concentration is a main cause.
Cross member bent laterally more than 50mm with top flange completely connection with floor has been totally lost.
Hole in side panel caused by impact.
Typical floor broken with x-member damaged due to heavy loading or rough fork truck operations. It could have no remarkable damaged appearance on top floor view, but it is a serious CSC issue.
Corner post dented inward and ISO framework dimension cannot be kept.
Corner post dent in and distorted more than IICL 25mm criteria.
Serious consequence after corner casting worn out if no repair.
Corner casting bottom aperture bent up to impair the twist lock cone securing, which is a serious safety issue.
Typical Corner casting worn out – remaining thickness unsafe for securing.