The dock workers in your example are the owners agents. In your example the terminal and shipping company have an arrangement that has the cargo owners as the responsible party for the loading. This kind of an arrangement is not universal though.
A more common arrangement has the terminal and shipping company in total charge of the cargo, as with overland shipping. The responsibility moves from the cargo owner to the first carrier, then to the terminal, then to the 2nd carrier and so on. Crude is handled that way. In your example the cargo owners agents are supposed to oversee and are responsible for at least the terminal ops. That may be, because of clauses in the insurance coverage and terminal contract.
This story here looks like the chem sales company owns everything. It's not clear whether the acid was coming, or going. This sales company owns(leases?) the tank farm, the terminal facility and the acid, at least until the customer recieves it.