Precautions for Putting-into- Use and for Disconnecting: 

1. Inspection before putting-into-operation: 

(1) Inspect # 1 and # 2 main steam interconnection electric valve and bypass valve, and main steam admission electrically operated valve and bypass valves of # 1 steam turbine and # 2 steam turbine main steam admission electrically operated valve and bypass valves for tightly closing; Inspect and close the extraction steam electric valve in Stage I of #1 and # 2 steam turbines.

(2) Inspect the electric steam-admission valve of the temperature-decreased pressure reducer, the electric steam-admission adjusting valve, manually-operated main valve of attemperation water, electric control valve of attemperation water, the electric valve and water draining valve at the outlet of temperature-decreased pressure reducer, the extraction electric valve from the temperature-decreased  pressure reducer to # 1 steam turbine and the electric valve from the temperature-decreased  pressure reducer to # 2  steam turbine for all closing tightly and the inspect the proper of the temperature-decreased pressure reducer for normal condition. 

(3) Inspect the pressure gauge, thermometer and flow meter to confirm they are in good condition.

(4) The safety valve shall be calibrated to confirm they are qualified and can move flexibly. 

(5) After the repair work is finished and the security measures are restored, the maintenance and installation personnel shall evacuate from the site. 

(6) The site shall be clean and the insulation shall be complete and in good condition. 

2. Procedures for Putting-into Use:

(1) After the inspection is finished and everything is normal, the monitor and the general dispatcher shall be reported. 

(2) After receiving the order of putting-into use, the monitor on -duty will contact the boiler operator to slightly open the electric-valve for steam admission, the operator on-duty for the steam turbine then opens the electric connection valves for the main steam and the water draining valves to heat the pipeline in front the electric valve for steam-admission of the temperature-decreased pressure reducer for 10-20 minutes time and the pressure is maintained at 0.15-0.2 Mpa. 

(3)Contact the boiler operator to fully open the steam admission valve, the pipe shall be free of vibration and leakage phenomenon; gradually open the electric valve for steam admission and the draining valves in front of the electric valve of the desuperheater and the pressure reducer. After normal pressure, slightly open the steam-admission valve and the water draining valves of the desuperheater and the pressure reducer to heat the body of desuperheater and the pressure reducer, and the pressure is maintained at 0.15-0.15 Mpa and the time is 10-20 minutes. 

(4) Open the low-pressure steam main pipe valves and the draining valves at the pipes from the air extraction pipe to the coking plant in advance,  inversely feed steam for heating pipelines to the back of the electric valve at the outlet of the temperature-decreased pressure reducer. 

(5) Regulate the steam-admission control valve of the temperature-decreased pressure reducer to increase the steam pressure to the pipeline pressure (0.5 Mpa), when the steam temperature is high, it is required to open the attemperation water valve properly in order to keep the temperature of the temperature-decreased pressure reducer consistent with the temperature( 170 ℃) of the pipeline. 

(6) After the inspection is normal, report to the monitor on-duty, and contact the general- dispatcher to prepare for combining the steam. After the condition permits, gradually open the electric valve at the outlet of the temperature-decreased pressure reducer and pay attention to adjustment of attemperation water in order to keep the steam temperature normal. 

(7) After the steam-combining is over, close the draining valves and report to the general dispatcher. 

3. Disconnection of the temperature-decreased pressure reducer: 

(1) After receiving the order of disconnection, the monitor on-duty contacts the boiler operator to prepare for the disconnecting the temperature-decreased pressure reducer and requires the operators to pay attention to the monitoring and cooperation in adjustment. 

(2) Procedures of disconnection: 

①Close the electric steam-admission control valve of the temperature-decreased pressure reducer and close the electric outlet valve of the temperature-decreased pressure reducer and the isolating valve of low pressure steam main pipe.

②Close the electric control valve and manually-operated valve of the attemperation water of the temperature-decreased pressure reducer . 

③Open the draining valve of the temperature-decreased pressure reducer. 

④ Close the electric steam-admission valve of the temperature-decreased pressure reducer. 

⑤ Open the draining valves at the pipes. 

⑥After the operation is finished, report to the monitor and shift engineer in charge. 

4. Treatment on emergency of temperature-decreased pressure reducer: 

(1) Principles for treatment on emergency in case the temperature-decreased pressure reducer is in emergency, the damage to the temperature-decreased pressure reducer must be reduced to the most extent.

(2) Overpressure accident of temperature-decreased pressure reducer: 

Phenomenon: 

①The indication of pressure gauge of the temperature-decreased pressure reducer exceeds the rated value.

②The relief valve acts.

Causes: 

① The steam-admission control valve is failure or is opened by mistake.

②The thermal load suddenly drops, causing overpressure. 

Treatment: 

①In case of malfunction of the control valve, it is required to adjust and recover as soon as possible. If it is in failure, according to the actual situation, the operation of temperature-decreased pressure reducer shall be disconnected as soon as possible and shall be inspected and treated. 

②The steam-admission valve of the temperature-decreased pressure reducer shall be immediately turned down and the pressure of the temperature-decreased pressure reducer shall be adjusted normal. 

(3) The attemperation water of the temperature-decreased pressure reducer is interrupted: Phenomenon: 

①The indication of temperature gauge of temperature-decreased pressure reducer exceeds the rated value. 

② The indication of pressure gauge of attemperation water rises abnormally or the pressure of the attemperation water decreases or decreases to zero.

Causes: 

①The control valve of the attemperation water is in failure or is closed by mistake.

②The feed pump is in failure, causing the interruption or decreasing of attemperation water. 

Treatment:

① In case of misoperation of the control valve, it shall be recovered as soon as possible; if it is in failure, according to the actual situation, the operation of temperature-decreased pressure reducer shall be disconnected as soon as possible and shall be inspected and treated.

② Contact with the shift chief-operator and the boiler operator to start the water- feeding bump as soon as possible to ensure the pressure of the attemperation water. 

(4) Water is carried in the steam from the temperature-decreased pressure reducer: 

Phenomenon: 

① The indication of main steam temperature gauge and the temperature gauge of the temperature-decreased pressure reducer drop sharply. 

②The main steam pipeline has water- hammering sound, and white steam emits from the valves and flange. 

③ The temperature-decreased pressure reducer accompanies with vibration noise. 

Causes: 

① The control valve of the attemperation water is in failure or is opened by mistake.

② The main steam temperature is too low or water in carried in main steam  ( the boiler is full of water). 

Treatment: 

① In case of misoperation of the control valve, it shall be recovered as soon as possible; If it is in failure, according to the actual situation, the operation of temperature-decreased pressure reducer shall be disconnected as soon as possible, the local water draining valve and the draining valves in front of and in the back of the interconnection valve shall be opened and the control valve shall be inspected and treated.

②Close the control valve and manual valve of the attemperation water, close the electric steam-admission valve and electric steam-admission control valve,  close the electric valve at the outlet of the temperature-decreased pressure reducer, open the draining valve of the temperature-decreased pressure reducer and the draining valves at the pipes, contact with the boiler operator to recover the main steam temperature as soon as possible. After the temperature is normal, put the temperature-decreased pressure reducer into use again. 

(5）Vibration of temperature-decreased pressure reducer:  

Phenomenon: There is obvious noise and vibration inside the temperature decreased pressure reducer.

The causes are: 

① During operating, the steam-admission and water-feeding are not properly adjusted. 

②The pipes are not fully warmed or water is not drained smoothly. 

③The control valve is in failure or the expansion chamber of the nozzle is in failure. 

Treatment: 

① During operation, the steam and water must be properly adjusted in order to avoid large adjustment.

② During putting-into operation and disconnection, it is required to ensure that the pipes are fully warmed and the water is drained smoothly.  

③If the adjustment is invalid, the vibration still cannot be eliminated, it is required to disconnect and check the parts.

5. Precautions for temperature-decreased pressure reducer: 

(1) The temperature-decreased pressure reducer is forbidden to operate beyond the parameters. 

(2) During putting-into-use or disconnection, the pipes shall be fully warmed and the water shall be drained smoothly in order to avoid vibration. 

(3)During normal operation, it is strictly prohibited to adjust the control valve of steam-admission and water-feeding valve by a large margin. 

(4) Before putting-into-use, the electric valve and the control valve shall be tested for opening and closing to ensure they are qualified. 

(5) If the relief valve has not been checked or it is jamming, it is forbidden to put the temperature-decreased pressure reducer into use.

(6) The pressure, temperature and flow meter shall be calibrated and the valves shall be maintained on a regular basis.

(7) Maloperation is forbidden at any moment.