Unheading device and method for coking drums

An unheading device for removal and replacement of a lower head unit of a vertically-oriented coking drum, comprising:

• (a) a head unit adapted for remote fastening to a lower flange of a coking drum;
• (b) at least eight pivotable clamping devices and associated detensioning means equally spaced around the perimeter of said head unit for detensioning and pivotably removing bolts located between said lower flange and an upper flange of said head unit, said bolts being each attached at their upper end to the lower end of each said clamping device;
• (c) platform means adapted for vertical movement to contact a lower side of said head unit and adapted for lowering the head unit and then moving it laterally to a side location relative to said lower flange, said platform means including an upper and lower plate separated by a linkage means located therebetween;
• (d) means for tipping said head unit in the side location at an angle of 20.degree.-60.degree. with the horizontal plane;
• and
• (e) means for lowering said head unit then moving it laterally and lifting said head unit to contact the coking drum flange for refastening the head unit into place on the coking drum.

A method for removing and replacing a lower head unit for a coking drum, the method comprising:

• (a) unfastening a flange joint between a lower head of a coking drum and a removable head unit attached thereto by detensioning a plurality of pivotable bolts and swinging the bolts outwardly and upwardly relative to the flange joint;
• (b) lowering the head unit from the coking drum and moving it laterally to a position at one side of the coking drum opening;
• then
• (c) moving the head unit laterally into position in vertical alignment with the coking drum lower flange, then raising the head unit into position against the flange of the coking drum lower head;
• and
• (d) refastening the pivotable bolts of the flange joint between the head unit and the coking drum.

A method for removing and replacing a lower head unit for a vertically-oriented coking drum, the method comprising:

• (a) unfastening a flange joint between a lower head of a coking drum and a removable head unit attached thereto by detensioning a plurality of pivotable bolts and swinging the bolts radially outwardly and upwardly relative to the flange joint, said bolts each being pivotally attached to a lower flange of the coking drum;
• (b) lowering the head unit away from the coking drum lower flange by a hydralically actuated platform and moving the head unit laterally to a position at one side of the drum opening;
• (c) tipping the head unit while raising a chute into contact with the coking drum lower flange;
• (d) lowering the head unit and moving it laterally to a position in vertical alignment with the coking drum lower flange;
• (e) raising the head unit into position against the coker drum lower flange;
• and
• (f) swinging the pivotable bolts downwardly into engagement with the flange and retensioning the bolts of the flange joint between the coking drum and the head unit.