The purpose of this work instruction is to outline the method and systems to be followed while expanding the boiler bank tubes at field sites

Aim

To avoid rotation of bearing outer race inside Bearing housing, tight fit is recommended between bearing and Housing. Also it is to be noted that If tight fit is not available, it will result in rotation of bearing outer race inside the housing in turn will result higher rate of wear of housing / outer race and further will result in high vibrations.

Requirement

Lead wire - 1 mm dia. x 50mm Long 1No.

Stainless Steel Shims 25mm x 25mm x 1 mm thk 4 nos.Procedure

1. Ensure bearing is properly fitted on the shaft and is locked with the help of locking nut and check Radial clearance between roller and outer race is as per the requirement. If radial clearance is more than specified, reduce radial clearance by further tightening of lock nut.

2. Ensure that housing is mounted properly on the base frame and is centered as shown in figure 1. (Top View)

Figure 1

If Housing is not centered with respect to shaft, loosen the housing base bolts and adjust the bearing housing accordingly.

3. Once Housing is centered, tighten housing base bolts fully with the help of torque wrench at specified torque. If torque wrench is not available, tighten the blots fully manually.

4. Place four equal size Shims (1 mm) at four corners of housing base as shown in figure 2. (TOP VIEW)

Figure 26.Place the lead wire (1mm dia x 50 mm Long) on the bearing axially as shown in below sketch (TOP VIEW) so that lead wire is placed in between the bearing outer race and housing top cover after assembly. Also while assembling top cover, ensure that lead wire is not dislocated.

7. Assemble the housing top cover on bottom part of housing and tighten top cover fully with the help of assembly bolts by torque wrench at specified torque. If torque wrench is not available, tighten the bolts fully manually.

8. Remove top cover of the housing from bottom part by removing tightening bolts.

9. After removing visually inspect the lead wire.

Conclusion

There should be slight reduction in diameter of lead wire at the area where it was placed over the bearing outer race. It indicates that there is tight fit between bearing outer race and bearing housing. And if no reduction in lead wire diameter is noted, it indicates that there is a clearance between bearing outer race and Housing.

If clearance is noticed between bearing outer race and bearing housing, bearing housing needs to be replaced with new one.SHAFT

Guidelines for Checking Tightness of Bearing Inside Housing

BEARING

This Gap should be uniform at all four places

SHAFT

BEARING

Equal size (25 x 25 mm x 1 thk) Shims at four places

SHAFT

BEARING

Lead Wire