Supersedes 3200-14
July 2001 Feb 2010
Cornell Pump Company
Impeller Lockscrew Installation
Impeller lockscrews are always right hand socket head capscrews. Stainless steel lockscrews are supplied with
Loctite 262, which should be applied to lockscrew thread and shaft thread prior to installation.
Torque for Impeller Lockscrews
First determine size and material of lockscrew, then torque to the appropriate value listed in the table below.
Stainless Steel Lockscrew
Nonmagnetic
Size (302, 303, 304, 316 Series)
.38 – 16UNC 20 Ft-lb
.50 – 13UNC 40 Ft-lb
.62 – 11UNC 90 Ft-lb
.75 – 10UNC 135 Ft-lb
1.00 – 8UNC 265 Ft-lb
1.12 – 7UNC 360 Ft-lb
1.25 – 7UNC 510 Ft-lb
1.50 – 6UNC 875 Ft-lb
Lubrication
Do not lubricate impeller lockscrew or tapped hole or between the lockscrew and the impeller washer or
between the impeller washer and the impeller. Make sure parts are clean and dry; however, it is not necessary
to remove the protective coating from the screw. Lubricated bolts can be overstressed with the torques
indicated.
DO NOT USE LOCKSCREW TO INSTALL THE IMPELLER
CAUTION
Lockscrew failure can damage impeller and volute.
The impeller screw must be of the best material, properly forged and machined to rigid specifications not
available from local suppliers.
Buy only lockscrews available from Cornell to be sure of quality.
Impeller Lockscrew Removal
1. Break loose impeller lockscrew with breaker bar. CAUTION: Care should be taken when removing
lockscrew to prevent damaging screw head.
2. If breaker bar will not loosen impeller lockscrew, apply heat to the lockscrew for 2-4 minutes. Do not
exceed 400° F. CAUTION: Care should be taken when applying heat so as not to receive serious burns.
3. Allow lockscrew to cool and remove with breaker bar.
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