Top Unheading Valve safety?

[Freddy MartinezParticipant]

News on a huge explosion at an Oil sands Coker a few weeks ago have been released pointing the cause of the fire/explosion to the opening of a live drum top unheading valve. Is this the first accident of this type on the industry?. What could be said about safety issues for top and bottom unheading devices?

[Anonymous]

For this type of unheading device top & bottom there are several interlock ithat no allowing to open this valves, this system are very safety unless the operator bypass some interlock

[Anonymous]

there are so many interlocks provided with top and bottom delta valves. which i mention below

1) drum must show off line by swich valve
2) sp1 & sp2 are closed ( valve used for isolation vapor from coke drum to fractionator)
3) sp4 & sp8 are closed ( valve used for isolation vapor from coke drum to blowdown)
4) both vent valve are in open condition
5) drum top pressure is either 0.05kg/ cm2 or below 0.05
6) drum top before quanche temperature is 150 c

when this all condition are satisfied then only we can open the top delta valve of that drum

i dont understand how did accident occured in cnrl ?

[Anonymous]

dont forget the valve donw stream of safety valve closed

[Author]

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