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