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