{TAIL ~ Expansion} of {HEAD ~ the underlying ring} brings the sealing material into contact with the surrounding tubular 
{ TAIL ~ Expansion } of { HEAD ~ the underlying ring } brings the sealing material into contact with the surrounding tubular
TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH