dont simply say ppl goyang kaki la.
i suspect this is all top management negligence issue.

postpone scheduled turnaround to optimize the production, or delay the repair works when u know dozens of ur pipelines actually have zero thickness.
what can a salarymen do when ur management dont approve and call for repair works?

im not saying this is the actual cause, but just to give just a little idea on how large corporation works.
any corporations for that matter. everyone must obey the whoever seems to be the mastermind.
SOP is SOP. but that can easily be bypassed.
engineers say things as accroding to what the bosses need them to say and engineer the reasonings themselves.