The vessel and {HEAD ~ the seal cover} have {TAIL ~ respective surfaces} that, when engaged, define a circumferential interior passage between the vessel and the seal cover 
have
The vessel and { HEAD ~ the seal cover } have { TAIL ~ respective surfaces } that , when engaged , define a circumferential interior passage between the vessel and the seal cover
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH