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Feedwater HeaterOld Method: Installation
or removal of the standard nuts was a headache! The upside-down
location, along with limited working room, created a very difficult
scenario to manipulate the large hydraulic wrench. A turntable
was required to hold and manipulate the tool into position. Furthermore,
a star pattern around the flange at incremental torque values was
followed. Raise the tool... lower the tool... move the tool.
The work was tedious and grueling. 10-12 hours with three workers
was required. The heater had a history of leakage, even after tightening
to the required 17,000 ft-lbs. Estimate 27-33 man-hour saving on installation!
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Superbolt
Solution: (16)
3-3/4" Torquenuts® were
used. Superbolt JL-M (Moly) lubricant was utilized to keep the
jackbolt torque to a low 91 ft-lbs. 1/2" impacts on a reduced
setting were used first. After three passes around each Torquenut® with
the impacts the jackbolts registered 75-85 ft-lbs. Approximately
1-1/2 passes with a calibrated torque wrench finished the job.
Total tightening time was approximately 1-1/2 hours. No leakage
to date.