are made by extra heavy wrought-steel flanges into which the tubes are expanded, 

 the flanges being bolted to corresponding flanges on the center fitting. The 

 superheater center fitting is provided with a standard extra heavy flanged super- 

 heated steam outlet and with an extra heavy flange for the reception of a 

 superheater safety valve. This safety valve is furnished as a part of the 

 regular equipment and is steel bodied, of the outside 

 spring type, set 2 pounds lower than the safety 

 valves of the boiler. The necessity for safety valves 

 with superheaters has been shown. 



Circular hand holes, closed by forged-steel, inside 

 fitting plates, give access to all expanded joints of 

 the connecting tubes. 



For equalizing the pressure between the drums 

 and the superheater center fitting, when the discharge 

 from the superheater is closed, a small equalizing pipe 

 is furnished connecting the center fitting to the satu- 

 rated steam space in the drum, thus breaking any 

 vacuum which might be formed in the center fitting, 

 causing it to be filled with water. 



LOCATION As stated, the superheater is located 

 in the triangular space below the drums and above 

 the inclined tubes. The headers, or manifolds, are 

 built into the brickwork of the hanging bridge wall, 

 bringing the handhole fittings above the third pass 

 of the boiler where they are exposed to only mod- 

 erate temperatures. 



The "U" form of the tubes and the absence of joints in the direct path 

 of the gases, made possible by the location described, give the best possible 

 conditions to assure the absence of stresses tending to leaky joints. 



The location is such as in no way to interfere with the cleaning or repairing 

 of the boiler proper. 



Furthermore, this location of the superheater is such that the entire first 

 pass of the boiler heating surface is between it and the fire and wide variation in 

 the temperature of the gases sweeping over the superheating surface is thus 

 avoided. 



SUPPORTS The forward ends of the superheater loops are supported 

 temporarily, during erection, from the drums above by light angles and rods. 

 These are left in place but are not depended upon for support as the tubes also 

 rest on brickwork built above the front flame bridge of the boiler. 



The lower superheater box is supported by "U " bolts passing over the drums. 



The superheater center fitting is carried on channels resting on pads on 

 the drums. 



CIRCULAR HANDHOLE 

 FITTINGS FOR ACCESS 

 TO SUPERHEATER IN- 

 LET AND OUTLET 

 CONNECTIONS 



53 



