CHAPTER XXXVI.

=STEAM BOILERS.=

=Strength of Boiler Shells= 350 =Strength of Boiler Plate= 351 Explanation of pressure in steam boilers 351 =Boiler Joints or Seams= 351 to 357 Forms of rivet joints 351 Single riveted lap joint 351 Double riveted lap joint 352 Single riveted butt joint with straps 352 Double riveted butt joint with straps zigzag riveted 352 Triple riveted lap joint zigzag riveted 352 Lap joint with covering plate 352 Double riveted lap joint chain riveted 353 Double riveted butt joints with double straps 353 Treble riveted butt joint with double straps 353, 354 Rules for spacing the rivets in boiler seams 353 Rule for finding diagonal pitch of riveted joints 353 High percentage joint 353 Rivets unevenly pitched 354 Rule for calculating the percentage strength of joint with unevenly pitched rivets 354 Strength of circumferential seams of stationary engine boilers 354, 355 Table of additions to be made to the factor of safety for various constructions of riveted joints 355 Table of diameter of rivets for single riveted lap joints 356 Rule for making rivet and plate area equal 336 Table of rivet diameter and pitch for single riveted lap joints 356 Rule for finding the pitch for double, diagonal riveted lap joints 356 Example in the use of rule for diagonal pitch of rivets 356 Rule for finding distance V where the diagonal pitch has been found 357 Comparing chain with zigzag riveted joints 357 =Interior of Boilers= 358 to 364 The internally fired flue boiler 358, 359 Boiler with Field tubes 350 Vertical water tube boiler 360 Construction of field tubes 360 Arrangement of field tubes 360 Vertical boilers with external uptakes 361 Horizontal return tubular boiler 361, 362 Construction of horizontal return tubular boiler 362, 363 Various arrangements of tubes in boilers 364 =Setting Boilers= 364, 366 Ground plan of brickwork 365 Setting full arch front boilers 365 Table of measurements for setting tubular stationary boilers with full arch front 366 Table of measurements for setting stationary boilers with half arch front 366 =The Evaporative Efficiencies of Boilers= 366 to 368 Table of the pressure, temperature and volume of steam 367 Calculating the evaporation of a boiler 368 =Care and Management of Boilers= 368 to 371 Examining safety valves 368 Water gauge glass 368 Gauge cocks 368 Lighting boiler fires 368 The thickness of the fire for boilers 368 Managing the fire 368 Shaking grate bars 369 The slice bar 369 The hoe 369 The poker 369 The clinker hook 369 The rake 369 The quantity of water in a boiler 369 Leaving the fire for the night 369 Leaving the safety valve for the night 369 Regulating the boiler feed 369 Dirty feed water 370 Defective feed pumps 370 Scale in boilers 370 Preventing the formation of scale 370 Feed water heaters 370 Low water in boilers 370 Priming or foaming 370 The known causes of priming 370 Wastefulness of priming 370 The detection of priming 370 To prevent or stop priming 370 Surface blow off cock or mechanical boiler cleaner 370 Blowing off a boiler 370 Blowing down a boiler 370 Washing out a boiler 371 Cleaning a boiler 371 Scaling a boiler 371 Examining a boiler 371