{TAIL ~ A retaining ring} surrounds the vessel and the seal cover at the position where the vessel and the seal cover meet to maintain an outer circumferential engagement between the seal cover and the vessel when pressure forces gases in {HEAD ~ the vessel} to flow into the circumferential passage and then outwardly from the pressure release opening 
{ TAIL ~ A retaining ring } surrounds the vessel and the seal cover at the position where the vessel and the seal cover meet to maintain an outer circumferential engagement between the seal cover and the vessel when pressure forces gases in { HEAD ~ the vessel } to flow into the circumferential passage and then outwardly from the pressure release opening
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