10. 11. 12. 14. 15. 16. 13. new  boilers,  expansion  movement  should  be checked to see that no binding or interference occurs. When   burning   oil,   prevent   incomplete combustion  in  the  furnace:  Unburned  oil  is deposited on the cooler surfaces in the back of the unit, such as the economizer and air heater, and   this   creates   a   potentially   dangerous condition. When  the  steam  drum  reaches  about  25  psig, close the vent valves on the boiler drum. Check the steam pressure gauge now to be sure that it is registering. Ease up on the stem of the main steam stop valve to  prevent  any  serious  expansion  stresses.  If there is no steam on either side of the main steam stop valve, gently lift and reseat it to make sure that it is not stuck. Open the drain valve on the boiler side of the main stop valve. Observe the water level carefully to ensure that no  water  is  carried  over  into  the  superheater. Maintain a normal water level in the drum by blowing  down  or  feeding  water  as  may  be required. Operate  the  vent  and  drain  valves  in  the superheater  headers  and  economizer  by following  the  manufacturer’s  instructions.  In general,  drain  valves  in  the  superheater  inlet header are closed first, followed by the drains in the superheater outlet header. In any case, the superheater outlet header drain and vent valves must  not  be  completely  closed  until  enough steam  flow  through  the  boiler  outlet  valve  is assured. Check  for  leaking  gasket  joints.  If  a  leaking gasket is discovered, shut down the boiler and tighten the joints. If the gasket still leaks, drop the pressure again, replace  the  gasket,  and  repeat  the  lighting  off sequence. Before cutting in the boiler, proceed as follows: 1.   Open all drain valves between the boiler and the header, especially the drains between the boiler and the two stop valves. 2. Warm up the steam line between the boiler and the header by backfeed through the drip line or by means of the bypass valve. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. When the steam line is thoroughly heated and at header pressure, open the bypass valve. When  the  boiler  pressure  almost  reaches  line pressure, open the bypass line around the main steam  stop  valve  to  equalize  pressures  and temperatures in the piping; then slowly open the main steam stop valve. As the boiler reaches line pressure and is actually steaming, slowly raise the  nonreturn  valve  stem  to  the  full  open position. After the boiler is on line, close all superheater drains. Inspect  the  entire  boiler,  and  close  any  drain valves that are not discharging condensate. Close the economizer-recirculating valve when an  adequate  continuous  feedwater  flow  is established. Close the drain valve at the nonreturn valve. Close  the  bypass  valve  around  the  nonreturn valve. A  boiler  with  a  pendant  (nondrainable) superheater  has  a  slightly  different  operation. Superheaters of this type trap condensate in the loops that must be boiled off before the firing rate can be increased and the steam flow started. Maintain a constant firing rate. The strength of thick  steam  drums  may  be  impaired  by excessive temperature differentials between the top and the bottom of the drum, if the proper firing  rate  is  not  maintained.  Tubes  may  start leaking at rolled seats and the superheater tubes may  overheat. On  boilers  generating  saturated  steam,  follow the  above  instructions  for  removing  air  and condensate. OPERATING  PROCEDURES Success in operating boilers depends largely upon the operator’s performance. No fixed set of rules can be established  to  fit  all  conditions.  Consequently,  the operator must see and interpret all prevailing operating conditions  and,  if  necessary,  take  action  to  control, modify,  or  correct  them.  To  be  able  to  do  this,  the operator  must  be  thoroughly  familiar  with  the characteristics  and  standard  operating  procedures  for the boiler for which the operator is responsible. This section acquaints you with some of the basic operating procedures  that  generally  apply  to  most,  if  not  all, 2-21