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