seal between the refractory surface and the tube sheet. The insulating pulp seal is not needed or used on the front head. Make sure the gaskets are in position when closing. When  you  are  closing  the  door,  bolts  should  be snug and tightened evenly to avoid cocking the door and  damaging  the  gasket.  Start  tightening  at  the  top center  bolt  and  alternate  between  the  top  center  bolt and  the  bottom  center  bolt  until  both  are  drawn-up tight.   Do   not   overtighten.   Continue   the   tightening sequence  along  top  and  bottom,  tightening  the  bolts alternately  until  the  door  is  secured  and  gas-tight.  After the  boiler  is  back  in  operation,  retighten  the  bolts  to compensate for any expansion. Q10. Q11. Q12. When plastic firebrick is used, troweling the new section of refactory will cause what condition to occur during the baking-out process? What  temperatures  are  required  to  bake  out plastic  firebrick? Leakage of combustion gases, loss of heat, and loss  of  operating  efficiency  can  be  caused  by what  condition? BOILER  OPERATIONS Learning   Objective:   Recognize   different   boiler checks,   start-up,   securing   procedures,   and   boiler emergencies. Understand the purpose and types of data in boiler operating logs. Proper sealing of the doors is essential to avoid  leakage  of  combustion  gases  and NOTE loss of heat and operating efficiency. The operation of a boiler consists of seven major phases:   (1)   prewatch   assumption   checks,   (2) preoperating  checks,  (3)  lining  up  systems,  (4) operating  procedures,  (5)  operating  checks,  (6) securing procedures, and (7) boiler emergencies. PREWATCH   ASSUMPTION CHECKS The   prewatch   assumption   checks   are   often neglected by boiler watch standers. Before you assume the responsibility of a boiler watch stander, you must complete specified checking procedures to ensure that the  equipment  in  service  is  in  sound  operating condition  and  is  functioning  satisfactorily.  When  the watch  is  relieved,  the  watch  stander  coming  on  duty inspects  the  instrument  readings  and  charts,  visually inspects  all  equipment,  and  exchanges  information with  offgoing  watch  standers.  Oncoming  watch standers  should  complete  the  following  inspections and tests before assuming duty: Visually inspect the setting and casting. Observe the furnace and firing conditions. Inspect the charts, logs, controls, and so forth, on equipment performance during previous watch. Inspect  the  fans,  dampers,  damper  drives,  and other driven auxiliaries. Test  the  water  columns  and  gauge  glasses. Obtain information from the watch standers on duty on the boiler operating condition and any unusual event or trouble that occurred during the previous  watch. Immediately  after  accepting  the  operational responsibility, you should make a complete inspection of all auxiliary equipment as follows: Inspect  all  electric  motor  drives  for  abnormal temperature, condition of bearings, and so forth. Inspect  the  fan  and  pump  bearings  for overheating and adequacy of lubrication. Visually  inspect  the  boiler  and  all  associated equipment,  listen  for  unusual  sounds,  friction, vibration, and other abnormal conditions. Inspect the burners, fuel supply, pilot systems, and other fuel supply components. Review the log sheets to obtain information on past operating conditions and unusual events. REOPERATING  CHECKS The   preoperating   checks   should   be   completed before lining up and lighting off a boiler. These checks are performed to ensure that the plant and associated equipment  are  in  a  safe  and  efficient  operable condition.  The  major  preoperating  procedures applicable to boilers in general, as well as additional procedures  for  gas-fired  and  oil-fired  boilers  are shown in tables B, C, and D, appendix II. LINING UP SYSTEMS After  you  have  completed  the  preoperating checks, your next job is to line up the boiler systems. The procedure used in lining up boiler systems (fuel, 2-19