The naturally rough finish of step 46 and plate 48 provides that necessary gaseous communication between {TAIL ~ compartment} 50 and chamber 56, while preventing fly ash and {HEAD ~ other solid particles} from rising into the upper chamber 56 
The naturally rough finish of step 46 and plate 48 provides that necessary gaseous communication between { TAIL ~ compartment } 50 and chamber 56 , while preventing fly ash and { HEAD ~ other solid particles } from rising into the upper chamber 56
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH