Page 385 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

364 Major Process Equipment Maintenance and Repair

Caution: If sealing steam is allowed to leak into the bearing hous-
ings, the lubricating oil may become contaminated and
form sludge and foam. Adjust the sealing steam accord-
ingly to prevent this condition.

6. Check the operation of the trip valve by striking the hand trip lever
(30, Figure 84). Close the steam inlet shut-off valve as the turbine
speed decreases.
7. Latch the resetting lever and slowly open the steam shut-off valve to
bring the turbine back to 500 r/min. Remove the inspection plugs (28,
Figure 8-5) from the bearing caps and check to be sure the oil rings
are rotating. Monitor the speed carefully during the low speed opera-
tion.

Caution: Do not leave the turbine unattended at any time during the
initial start-up.

8. Introduce cooling water to bearing housing cooling chambers to
prevent overheating (See Table 8-5). Listen for any rubbing, un-
usual noises or other signs of distress in the turbine. Feel all bear-
ing housings and oil lines to detect overheating or vibration. Do
not continue to operate if any of these conditions exist. Shut down
the turbine; locate and correct the cause of the problem. See the
troubleshooting guide in %lune 2 for possible causes and correc-
tive actions for abnormal conditions which might occur.
9. When the turbine is thoroughly warmed up and low speed opera-
tion is determined to be satisfactory, increase the speed with the
governor speed adjustment until the turbine is operating at the
rated speed shown on the turbine nameplate. (Adjust the governor
as outlined in Governor Operation, Chapter 10.) If operational
problems occur, shut the turbine down and locate and correct
cause. (Refer to the troubleshooting guide in Vblume 2 for possible
causes and corrective actions for abnormal operating conditions.)
Note: If the turbine is pressure lubricated, the oil pressure should
be 7 to 9 psig (0.5 to 0.6 bar).

10. Check the overspeed trip by overcoming the governor to actuate
the overspeed trip mechanism. Refer to Governor Operation,
later, for specific details on overspeeding the turbine.

Caution: Do not operate the turbine more than 2 percent above
the rated trip speed shown on the turbine nameplate. If
the overspeed trip does not operate within 2 percent of