Abstract: A bottom unheading device adapted for unheading vertical vessels such as coking drums. The unheading device includes a cover unit adapted for attachment to a lower flange of a coking drum and which is fastened by a plurality of swing bolts which are disconnected by remotely operated detensioning equipment, and a frame which can lower the cover unit and a carriage which moves it laterally to one side. A chute attached to the frame can be raised into engagement with the coking drum lower flange for removal of coke from the drum. Following such coke removal, the chute is lowered and the cover unit is moved laterally and remotely reconnected to the coking drum lower flange. The invention also discloses a method for remotely operating the unheading device.