SECURING  PROCEDURES The recommended procedures for securing boil are as follows: 1.   Reduce the load on the boiler slowly, cutting ers out the  fuel  supply  by  proper  operation  of  the fuel-burning equipment. 2. Maintain normal water level. 3.   When the boiler load is reduced to about 20% of rating, change the combustion control and the feedwater control to manual operation. 4. Before securing the final fuel burner, open the drain valves at the steam and nonreturn valve and  the  drain  valve  on  the  superheater  outlet header.  Be  sure  the  bypass  valve  around  the nonreturn valve is closed. 5. Secure the final fuel burner when the load has been reduced sufficiently. 6.   Continue operating the draft fans until the boiler and the furnace have been completely purged. 7. Shut down the draft fans. 8.   Close the dampers,  including  the air heater and superheater bypass dampers, when  provided. 9.  Follow  the  manufacturer’s  instructions  for  the rate of cooling the boiler. A thermal strain may occur if the change is too fast. 10.  When  the  boiler  pressure  has  started  to  drop, close the steam stop and nonreturn valve. 11.   When the boiler no longer requires any feed and the nonreturn valve is closed, open the valve in the recirculating connection of the economizer, if  provided. 12. Let the boiler pressure drop by relieving steam through  the  superheater  drain  valve  and  the drain valve at the nonreturn valve. If the boiler is losing pressure at a rate faster than specified by the  manufacturer,  throttle  the  drain  valves  as necessary to get the proper rate. Do not close the valves completely. 13. When the drum pressure drops to 25 psig, open the drum vent valves. 14. If a regenerative type of air heater is used, the rotor may be stopped when the boiler exit gas temperature is reduced to 200°F. 15.   The boiler can be emptied when the temperature of  the  boiler  is  below  200°F.  Before  sending someone into any part of the boiler, close and properly tag all controls, valves, and drains or blowdown valves connected with similar parts of other units under pressure at the time. This move  prevents  any  steam  or  hot  water  from entering  the  unit.  The  tags  are  to  be  removed only by the authorized person who tagged out the  boiler  and  must  remain  in  place  until  the work  is  completed.  Ventilate  the  boiler thoroughly and station a person outside. Inside, use only low voltage portable lamps provided with suitable insulation and guards. Even 110 volts can kill under the conduction conditions inside a boiler. All portable electrical equipment should   be   grounded;   and   electric   extension cords  should  be  well  insulated,  designed  to withstand rough usage, and maintained in good condition. BOILER  EMERGENCIES Typical   emergency   situations   encountered   with the  operation  of  boilers  are  (1)  low  water,  (2)  high water, (3) serious tube failure making it impossible to maintain  water  level,  (4)  flarebacks  caused  by  an explosion in the combustion chamber, (5) minor tube failure indicated by trouble in maintaining water level under  normal  steam  demand,  and  (6)  broken  gauge glass on the water column. Table F, appendix II, lists the  safe  procedures  to  follow  when  these  boiler emergencies occur. BOILER OPERATING LOGS The  main  purpose  of  boiler  operating  logs  is  to record  continuous  data  on  boiler  plant  performance. Logs become a source of information for analyzing the operation of the boiler for maintenance and repair. The daily   operating   log   sheets   provide   the   basic information  around  which  maintenance  programs  are developed. The log is arranged for use over a 24-hour period divided into three 8-hour shifts. Log sheets vary among  different  activities,  but  you  should  have  no difficulty  in  making  log  entries  once  you  understand what information is required. The types of information to be entered in the appropriate column of the log are as follows: Steam pressure. Based on steam gauge readings and indicates the performance of the boiler. Steam flow. Actual output of the plant, in pounds per  hour,  to  obtain  steam  flow.  The  data  from  these entries are used to determine the number of boilers to operate for greatest efficiency. 2-23