Tarry drums are a complicated question. First, we must clarify why it was a tarry drum…..
1. low heater COT for some time?
2. Low drum vapor (DOV) temp for some time?
3. Short run drum (<4h), never reached DOV temp
Second and possibly separately, what is the cause of the steam failure? Power failure or other? Are you able to get water into the drum without steam stripping?
All of these scenarios could be handled differently by its own separate procedure. Sorry, not the clearest answer but each scenario is different. We recommend you think through each scenario completely and have a plan.