{HEAD ~ Gas entry pipes} 39 and 40 have {TAIL ~ extensions} 41 and 42, respectively, into tube 16 
have
{ HEAD ~ Gas entry pipes } 39 and 40 have { TAIL ~ extensions } 41 and 42 , respectively , into tube 16
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH