Chapter 11-BOILER FITTINGS AND CONTROLS 



LONGITUDINAL SECTIONAL ELEVATION 



DESIGNATION OF SYMBOLS 



A - FEED INLET 



B - FEED PIPE 



C - DRY PIPE 



D - MAIN STEAM OUTLET 



E - SURFACE BLOW-OFF PIPE 



F - SURFACE BLOW-OFF NOZZLE 



G - DESUPERHEATER INLET 



H - DESUPERHEATER OUTLET 



J - DESUPERHEATER 



K - CHEMICAL FEED INLET 



L - CHEMICAL FEED PIPE 



M- SWASH PLATES 



N - BAFFLE 



P - SAFETY VALVE NOZZLES 



CROSS SECTIONAL ELEVATION 



38.42 



Figure 11-1.— Arrangement of internal fittings in 

 header-type boiler. 



the drumhead to the surface blow-off nozzle (F). 

 When the surface blow valve is opened, the pres- 

 sure in the drum forces the water above the 

 blow-off pipe to go into the pipe through the 

 holes on the top surface; the water from the 

 surface blow-off pipe then leaves the boiler by 

 way of the surface blow valve. 



The desuperheater (J) is an assembly of pipe 

 lengths and return bends located below the water 

 level of the drum. The superheater steam enters 

 the desuperheater through the desuperheater 

 inlet (G), gives up its superheat to the water in 

 the steam drum, and then— once again at or very 

 close to saturation temperature — passes through 



the desuperheater outlet (H) before entering the 

 auxiliary steam line. 



The chemical feed inlet (K) is connected to 

 the internal chemical feed pipe (L). The chemi- 

 cal feed pipe has holes drilled in it to allow 

 even distribution of chemicals used for boiler 

 water treatment. 



Swash plates (M) are used to reduce the 

 surging or swashing of water from one end of 

 the drum to the other as the ship moves. In 

 addition, the swash plates act as supports for 

 the internal feed pipe and for the desuperheater. 



The safety valve nozzles (P) are not nor- 

 mally considered internal fittings. These nozzles 



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