{HEAD ~ The internal diameter} of {TAIL ~ the tube section} 20 is equal to the internal diameter of the adjacent parts of pipes 10 and 12 
of
{ HEAD ~ The internal diameter } of { TAIL ~ the tube section } 20 is equal to the internal diameter of the adjacent parts of pipes 10 and 12
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH