C) sealing {HEAD ~ the hole} by connecting {TAIL ~ 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 the compressed part of the tube 
by connecting
C ) sealing { HEAD ~ the hole } by connecting { TAIL ~ 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 the compressed part of the tube
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL 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 OTH OTH OTH OTH