Interrupted feed can result in a very serious safety hazard if not handled properly. It can also become a significant operational problem even if the safety hazards are mitigated. Each company should have interrupted drum procedures. Depending on where the drum is in the fill cycle, feed has been successfully re-introduced into a partial drum. There are operational hazards and you can aggravate the potential safety hazards by putting feed back into the drum.
There have been a number of presentations over the years given at Coking.com conferences that have highlighted the potential foam over problem with putting feed back into a partially filled drum. There have also been presentations over the safety hazards of a tarry drum. Equilon Anacortes had six people fatally injured from a tarry drum that was not cooled before the heads were removed.
The conclusion from the Anacortes incident was that water should be used to cool the coke drum before removing the heads. If the normal way of adding water to the drum is not available, some other method is needed to remove the heat from the contents of the drum before removing the top and bottom heads as the drum will not cool to a safe value without actively removing the heat.
The more low temperature feed barrels that are put into the coke drum, the higher the potential hazard from a foam over or tarry drum standpoint. Setting a limit of the maximum number of low temperature feed bbls that can enter the drum before bypassing is something each company should do to prevent severe operational or safety hazards.