C) sealing {HEAD ~ the hole} by connecting one end of a tube of a predetermined length to the outside of the burr, compressing the protruding end of the tube, and then welding {TAIL ~ the compressed part} of the tube 
by welding
C ) sealing { HEAD ~ the hole } by connecting one end of a tube of a predetermined length to the outside of the burr , compressing the protruding end of the tube , and then welding { TAIL ~ the compressed part } of the tube
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH