The de-header valve is equipped with a sliding blind having an orifice therein, a flat surface adjacent the orifice, a stroke slightly greater than the diameter of the orifice in the de-header valve, and upper and lower seats, wherein one of such seats is a dynamic, live loaded seat that is capable of automatic adjustment so as to seal the blind between the upper seat. As such, the sliding blind can be moved in a substantially linear bi-directional manner between upper and lower seats, or dual seats, thus causing the orifice located thereon to move between an open, closed, and partially open position relative to the orifice in the coke drum. In a closed position, the de-header valve and coke drum are prepared to receive the byproduct feed from the refinery process used to manufacture coke.
http://www.freepatentsonline.com/20040045803.html
(enthält auch eine Schemazeichung der "de-header valve"

live load = Verkehrslast, Auflast, tempäre last (vorwiegend ruhend)
(Kucera, The compact dictionary of exact science and technology)

Anstelle von live-load habe ich mit load-bearing (lasttragend) ein Synonym gefunden.