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