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.

NOTE

Proper sealing of the doors is essential to avoid leakage of combustion gases and loss of heat and operating efficiency.

Q10. When plastic firebrick is used, troweling the new section of refactory will cause what condition to occur during the baking-out process?

Q11. What temperatures are required to bake out plastic firebrick?

Q12. 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.

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