{HEAD ~ The disposition} and configuration of {TAIL ~ the grooves} 45 is such that the seal at sealing element 49 is disestablished prior to disestablishment of the metal to metal seal between the gate face and the righthand end of seat element 38, so that high pressure differentials are not imposed across the elastomeric seal 
{ HEAD ~ The disposition } and configuration of { TAIL ~ the grooves } 45 is such that the seal at sealing element 49 is disestablished prior to disestablishment of the metal to metal seal between the gate face and the righthand end of seat element 38 , so that high pressure differentials are not imposed across the elastomeric seal
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