A seal is installed in the groove on the open end of {HEAD ~ the cup} to seal to the primary face of a tubesheet around {TAIL ~ the tested rib plug} 
to seal around
A seal is installed in the groove on the open end of { HEAD ~ the cup } to seal to the primary face of a tubesheet around { TAIL ~ the tested rib plug }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL