manufacturer. To determine the surface speed of a grinding wheel, use the equation
below:
below:
Surface speed = sfpm =
rpm x D
12
where:
rpm = speed of the grinder (revolutions per minute)
D = diameter of the wheel in inches
D = diameter of the wheel in inches
The selection of the grinder requires consideration of several factors. The grinder
should be lightweight and small enough to fit where the grinding will be done. The
grinder should be capable of running at a speed that will give the required surface
speed of the wheel. The availability of the type of power, such as electricity or air,
required to operate the grinder should also be considered.
should be lightweight and small enough to fit where the grinding will be done. The
grinder should be capable of running at a speed that will give the required surface
speed of the wheel. The availability of the type of power, such as electricity or air,
required to operate the grinder should also be considered.
All wheels should be carefully inspected for defects before use. A simple "ring" test,
where the wheel is suspended and tapped with a nonmetallic object, may be used. If
the wheel sounds cracked, do not use it. Wheels should be handled carefully - if a
wheel is dropped, it should not be used. Wheels should be installed properly. Check
that all flanges and mounting nuts are in the correct places. New wheels should be run
for 1 minute before use. Cold grinding wheels should be loaded gradually to reduce
the chance of breakage. Operators should always wear eye protection and should not
stand directly in front of the work.
where the wheel is suspended and tapped with a nonmetallic object, may be used. If
the wheel sounds cracked, do not use it. Wheels should be handled carefully - if a
wheel is dropped, it should not be used. Wheels should be installed properly. Check
that all flanges and mounting nuts are in the correct places. New wheels should be run
for 1 minute before use. Cold grinding wheels should be loaded gradually to reduce
the chance of breakage. Operators should always wear eye protection and should not
stand directly in front of the work.
8. SEAL RINGS
Turbine seal ring replacement is usually scheduled to coincide with major unit
overhaul or uprating requiring disassembly. Generally seal ring replacement is
required before seal clearances reach 200 percent of design clearances. As seal ring
clearances increase beyond 200 percent, significant efficiency losses can be expected
as well as changes in the hydraulic downthrust of the unit which can lead to bearing
damage.
overhaul or uprating requiring disassembly. Generally seal ring replacement is
required before seal clearances reach 200 percent of design clearances. As seal ring
clearances increase beyond 200 percent, significant efficiency losses can be expected
as well as changes in the hydraulic downthrust of the unit which can lead to bearing
damage.
Standard practice in Reclamation is to select dissimilar materials for stationary and
rotating rings to resist galling and seizure in the event the rings make contact. The
materials selected must also have good cavitation erosion, corrosion, and abrasion
resistance.
rotating rings to resist galling and seizure in the event the rings make contact. The
materials selected must also have good cavitation erosion, corrosion, and abrasion
resistance.
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