{TAIL ~ The warped intermediate portion} of {HEAD ~ the pipe material} is fixed to the supporting surface portion of the head pipe by welding 
{ TAIL ~ The warped intermediate portion } of { HEAD ~ the pipe material } is fixed to the supporting surface portion of the head pipe by welding
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH