wherein the annular surface has a radially inner portion and a radially outer portion, and said continuous seal is located at least on said radially outer portion, while the radially inner portion allows the seal of the valve to be brought into {HEAD ~ sealing engagement} with {TAIL ~ the tubular body} 
wherein the annular surface has a radially inner portion and a radially outer portion , and said continuous seal is located at least on said radially outer portion , while the radially inner portion allows the seal of the valve to be brought into { HEAD ~ sealing engagement } with { TAIL ~ the tubular body }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL