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RE: steam incident



I do not think that the condensate flashed. More than likely, steam entered the drum and lifted the condensate. There is also the possibility that there was residual steam condensate downstream in the vapor line, either upstream of the first steam-purged block valve or in the spool between the two block valves. Steam could have entered by that side (via the downstream valves or spool) and lifted condensate toward the depressurized coke drum.

Bottom line: This event points to the need to drain and isolate (using close blinds) coke drum piping that is to be opened for maintenance. Relying only on closure of the double block valves is not sufficient to prevent steam incursion into the piping system being repaired or maintenanced.

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