Handbook Of Shaft Alignment Episode 3 Part 5 potx

FIGURE 21.37 Remove the motor. FIGURE 21.38 Measure the eccentricity at the lower end of the pump shaft. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 690 6.10.2006 12:19am 690 Shaft Alignment Handbook, Third Edition the measurements as shown in Figure 21.41 and Figure 21.42. Ideally the runout should adhere to the guidelines discussed in Chapter 5. 4. Determine if the pump flange face is centered and perpendicular to the pump shaft as shown in Figure 21.43 through Figure 21.45. Since the mating flange faces are often rabbeted fits, the rabbet surface is used to check for concentricity and the flange face surface is used for perpendicularity checks. 21.1.6.1 Additional Information on Vertically Mounted Centrifugal Pumps When the motor and pump are bolted together, they effectively become one contiguous frame and OL2R machinery movement has very little effect on the alignment of the shafts. Since the entire drive system is typically attached to a floor or the structure of the building, checks should be made to insure that the motor–pump assembly is firmly attached to the floor via the anchor bolts. Leakage at the packing gland and frequent replacements of the mechanical seal are indications that a misalignment condition or excessive runout may be the culprit. Excessive vibration can often be attributed to unbalance conditions in the motor armature or pump shafts but can also be traced to excessive runout conditions in the rotating assembly. FIGURE 21.39 Measure the eccentricity at the upper end of the pump shaft. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 691 6.10.2006 12:19am Alignment Considerations for Specific Types of Machinery 691 21.1.7 BLOWERS AND FANS There are several different designs of fans and blowers and again, it would be difficult to cover every aspect of these types of machines. Similar to pumps, their purpose is basically to move large volumes of a compressible fluid at low pressures from point A to point B. A large majority of smaller horsepower (5 to 200 hp) units are belt-driven as shown in Figure 21.46. Larger units are more frequently direct-driven as shown in Figure 21.47 and Figure 21.48. Again, the temperature of the gas that is conveyed has a great effect on the OL2R conditions of the fan. As discussed in Chapter 5, the ductwork attached to the fan can have a tremen- dous influence on obtaining and maintaining accurate alignment, so that many people are Total indicated runout (TIR) 0 N S E −2W 0 N S EW 0 N S EW 0 −2.5 +16.5 +3 +1 +18 +4 +4 −7.5 N S EW 0 −0.5 −4 N S EW 0 +3 −1 −2.5 View from above when runout measurements were taken N S EW Key 0 50 10 40 20 30 + _ 10 40 20 30 5 in. 6 in. 20 in. 44 in. 11.25 in. FIGURE 21.40 Eccentricity measurements along the pump shaft and its extension. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 692 6.10.2006 12:19am 692 Shaft Alignment Handbook, Third Edition unwilling to even try to reposition fans and blowers and henceforth declare them the ‘‘stationary’’ machine when aligning them. In some situations, where the fan blades are center mounted on the shaft and the shaft is supported by bearings at each end, the position of the shaft is dictated by the positions of the bearing pedestals that are not directly attached to the fan housing. The fear in altering the position of the fan bearings is that internal fan blade to shroud clearances could be upset and rubs could occur. Here again, the graphing or modeling technique can be used not only to align the shafts, but also to position the fan housing to properly set fan blade to shroud clearances. FIGURE 21.41 Split collar and bearing. FIGURE 21.42 Bracket attached to outer race of rolling element bearing held in place with the split collar. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 693 6.10.2006 12:19am Alignment Considerations for Specific Types of Machinery 693 Figure 21.49 shows a motor-driven fan, where the fan shaft and wheel are supported on pedestals that are separated from the fan housing itself. It is possible for the centerline of the fan housing not to be collinear with the centerline of rotation of the fan shaft. To determine where the center of the fan housing is, take gap measurements between the fan wheel and the shroud at the top, bottom, and both sides at the inboard and outboard ends. For example, top and bottom gap measurements were taken between the fan wheel and the stationary FIGURE 21.43 Checking for concentricity on the rabbeted surface. FIGURE 21.44 Checking for perpendicularity on the flange surface. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 694 6.10.2006 12:19am 694 Shaft Alignment Handbook, Third Edition Pump mating flange face and rabbeted fit runout N S EW 0 0 50 10 40 20 30 + _ 10 40 20 30 0 0 0 +9 −10 −4 −1 −2 −4.5 −9.5 −6.5 −3.5 −16 Measurements on male rabbet Apparent centerline of male rabbet Centerline of shaft Exaggerated apparent position of male rabbet 0 FIGURE 21.45 Concentricity and perpendicularity measurements on pump. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 695 6.10.2006 12:19am Alignment Considerations for Specific Types of Machinery 695 shroud at both the inboard and outboard ends as shown in Figure 21.49. Notice that the gap at the twelve o’clock position at the inboard end is 30 mils and at the six o’clock position the gap is 270 mils. By adding these two gaps together, the total gap is 300 mils. For the fan wheel to be centered in the up and down direction, there should be a gap of 150 mils at both the twelve- and six o’clock positions. Since the gap is greater at the six o’clock position (270 mils), the housing is 120 mils low at that point with respect to the fan shaft and wheel. Likewise the outboard end is 40 mils too low. FIGURE 21.46 Belt-driven fan. FIGURE 21.47 Direct-driven fan. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 696 6.10.2006 12:19am 696 Shaft Alignment Handbook, Third Edition Figure 21.50 shows the side view of the motor shaft, the fan shaft, and the centerline of the bore of the fan housing. Assuming that there are no shims under any of the motor, fan bearings, or fan housing bolts, the overlay line could be projected to pivot at the outboard end of the motor and the outboard bearing of the fan and shims can be added under the inboard end of the motor, the inboard bearing of the fan, and the inboard and outboard foot bolts of the fan housing as shown in Figure 21.50. A similar alignment model can be generated in top view showing the lateral positions of the motor shaft, the fan shaft, and the centerline of the bore of the fan housing to achieve correct lateral alignment. Once again, the alignment modeling method gives us the opportunity to add as many pieces of infor- mation about our drive system as necessary to enable us to align all the components regardless of its complexity. Typical OL2R movement range of blowers and fans: Vertical movement: 0 to 80þmils upward typically asymmetrical (i.e., inboard and outboard ends do not move up the same amount) Lateral (sideways) movement: 0 to 20þ mils Axial movement: 0 to 50þ mils 21.1.7.1 Additional Information on Horizontally Mounted Blowers and Fans Moderate to excessive off-line soft foot conditions have been experienced on virtually every type of fan and blower regardless of frame construction design. Frequently, the fan bearings are bolted to the fan frame or to a pedestal, which may also have a soft foot condition. Bear in mind that the axial movement amounts mentioned above are for the casing or housing. The shaft may expand more than that and may influence how you should set the off-line shaft end to shaft end distances. For belt-driven fans, excessive vibration is often traceable to excessive face or rim runout in sheaves. Slow increases of vibration on fans often occur due to a dirt buildup on the fan wheel or uneven erosion or corrosion of the fan wheel. Since access to the fan wheel is usually accessible in the field, balancing of fans is frequently done in situ. Make sure the alignment and runout are acceptable and that any dirt buildup on the fan wheel has been removed before balancing. Balancing is the last thing I do. There is nothing more frustrating than attempting to ‘‘balance out’’ an alignment or runout problem. FIGURE 21.48 Aligning a direct-driven fan. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 697 6.10.2006 12:19am Alignment Considerations for Specific Types of Machinery 697 21.1.8 COMPRESSORS The variation in compressor design is as diverse as pumps and fans. Figure 21.51 shows a small biogas compressor. Figure 21.52 shows a multistage horizontally split compressor with the upper casing removed. Figure 21.53 shows a multistage bullgear-driven compressor. Figure 21.54 shows axial flow compressors. Figure 21.55 shows a V-shaped two-stage recipro- cating compressor. Figure 21.56 shows a chiller compressor. In the refining and chemical industries, it is not uncommon for several compressors to be driven by a single steam or gas turbine. When gases are compressed, heat is generated and thereby casing expansion typi- cally occurs. On multistage compressors such as the ones shown in Figures 21.51 through 94 in.64 in. 16 in.12 in. 10 in. Motor Fan 4 in. Near indicator Far indicator Up Side view Scale: 20 in. Motor Fan 10 in. 10 in. 0.190 in. 0.110 in. 0.030 in. 0.270 in. 4 in. 4 in. Gaps between fan wheel and shroud Total gap = 0.300 in. Even gap = 0.150 in. Fan wheel to shroud gap measurement points Fan housing foot bolts Fan bearing bolting points 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 FIGURE 21.49 Motor-driven fan where fan shaft is supported on separate pedestals. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 698 6.10.2006 12:19am 698 Shaft Alignment Handbook, Third Edition Up Side view Scale: 20 in. 50 mils B E 0 T B E 0 T Near indicator +10 −36+16 Sag compensated readings −20 +24 −14 Far indicator Motor Fan Centerline of fan housing Lower 72 mils down Raise 42 mils up Overlay line Pivot Pivot Raise 70 mils up at inboard bearing Raise 180 mils up at inboard fan housing bolts Raise 55 mils up at outboard fan housing bolts WW FIGURE 21.50 Side view of motor shaft, fan shaft, and fan housing bore. FIGURE 21.51 Small biogas compressor. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 699 6.10.2006 12:19am Alignment Considerations for Specific Types of Machinery 699 [...]... gaps –0.00 75 0.00 25 1. 250 0 1. 250 0 1. 250 0 1. 250 0 0.01 05 1 .50 00 1 .50 00 1 .50 00 1 .50 00 0.0120 FIGURE 21. 73 Bearing and wear ring clearance measurements 1. 250 0 1. 250 0 1. 250 0 1. 250 0 0. 030 0 0. 030 0 0. 030 0 0. 030 0 0.01 65 0. 030 0 0. 030 0 0. 030 0 0. 030 0 Piotrowski / Shaft Alignment Handbook, Third Edition DK 432 2_C021 Final Proof page 719 6.10.2006 12:19am 719 Alignment Considerations for Specific Types of Machinery... 1. 255 00 1.2 450 0 1.246 25 1.2 53 7 5 0.0100 North South West East Snap gauge and OD mike 1.24 850 1. 254 00 1. 251 25 1.248 75 –0.0 055 North South West East Snap gauge and OD mike 1.49100 1 .50 900 1 .50 5 25 1.494 75 –0.0180 North South West East Feeler gauges 0.019 75 and OD mike 0.040 25 0. 036 00 0.02400 –0.02 05 North South West East Feeler gauges 0.016 75 and OD mike 0.0 432 5 0. 038 25 0.021 75 –0.02 65 Lower generator bearing... to verify position in east−west direction 30 20 40 10 50 _ 0 + 30 20 40 10 30 50 _ 0 + 20 40 10 40 10 30 20 Slowly rotate shaft 30 20 40 10 50 _ 0 + 40 10 30 20 30 20 40 10 50 _ 0 + 40 10 30 20 30 20 10 40 _ 0 + 50 10 40 30 20 30 20 10 40 _ 0 + 50 10 40 30 20 30 20 Dial indicators set to measure runout 40 10 50 _ 0 + 40 10 30 20 30 20 40 10 50 _ 0 + 40 10 30 20 FIGURE 21.69 Runout checks measure those... device measurement Zero at position A Orientation of shaft North plumb wire Position A Position B Position C Position D Electric mike 0 .51 20 0 .50 85 0 .50 55 0 .50 25 0.0000 – 0.0 0 35 – 0.00 65 – 0.00 95 +to the south –to the north South plumb wire Position A Position B Position C Position D Electric mike 0.6280 0. 631 5 0. 634 5 0. 637 5 0.0000 0.0 0 35 0.00 65 0.00 95 +to the north –to the south West plumb wire Position... Piotrowski / Shaft Alignment Handbook, Third Edition DK 432 2_C021 Final Proof page 716 6.10.2006 12:19am 716 Shaft Alignment Handbook, Third Edition Scale the diameter of the thrust runner on the top part of the T-bar overlay Rotor runout plot Upper bearing Thrust bearing 10 50 _0 + 40 10 30 30 20 20 30 20 30 30 10 40 50 _0 + 10 40 20 20 30 10 40 50 _0 + 10 40 20 Position C 9 mils TIR 30 10 40 50 _0 + 10... Which alignment condition is correct? Piotrowski / Shaft Alignment Handbook, Third Edition DK 432 2_C021 Final Proof page 707 6.10.2006 12:19am 707 Alignment Considerations for Specific Types of Machinery Align jackshaft to shaft with no offset and no angle here Temporary supports Bolt jackshaft to shaft 10 _ 0 + 10 20 20 30 30 40 10 50 _ 0 + 40 Dial indicator and magnetic base 10 20 20 30 30 40 50 40... aligning shafts that have problems with them? If you align the centerlines of rotation and then discover that there is an issue with one or more of the shafts, all of the effort you spent in aligning is waste of time Why? Because you may have to replace Piotrowski / Shaft Alignment Handbook, Third Edition DK 432 2_C021 Final Proof page 7 13 6.10.2006 12:19am 7 13 Alignment Considerations for Specific Types of. .. location of the bore of the fan housing, air gap measurements are taken between the armature and stator at both ends of both machines to determine the centerline of the bore Piotrowski / Shaft Alignment Handbook, Third Edition DK 432 2_C021 Final Proof page 704 6.10.2006 12:19am 704 Shaft Alignment Handbook, Third Edition 0.090 in E W 0.120 in 0.160 in Motor Temporary bearing support 10 _ 0 + 30 50 40 40 50 ... conditions FIGURE 21 .55 Two-stage reciprocating compressor Piotrowski / Shaft Alignment Handbook, Third Edition DK 432 2_C021 Final Proof page 702 6.10.2006 12:19am 702 Shaft Alignment Handbook, Third Edition FIGURE 21 .56 Chiller compressor mentioned above are for the casing or housing The shaft may expand more than that and may influence how you should set the off-line shaft end to shaft end distances... water turbine shaft to the lower end of the generator armature as shown in Figure 21. 63 The upper bearing of the generator is both a radial and thrust bearing that supports the weight of the armature and the water turbine A lower radial bearing is located above the rigid Piotrowski / Shaft Alignment Handbook, Third Edition DK 432 2_C021 Final Proof page 708 6.10.2006 12:19am 708 Shaft Alignment Handbook, . −2W 0 N S EW 0 N S EW 0 −2 .5 +16 .5 +3 +1 +18 +4 +4 −7 .5 N S EW 0 −0 .5 −4 N S EW 0 +3 −1 −2 .5 View from above when runout measurements were taken N S EW Key 0 50 10 40 20 30 + _ 10 40 20 30 5 in. 6 in. 20. fan. Piotrowski / Shaft Alignment Handbook, Third Edition DK 432 2_C021 Final Proof page 696 6.10.2006 12:19am 696 Shaft Alignment Handbook, Third Edition Figure 21 .50 shows the side view of the motor shaft, . above the rigid 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 Align jackshaft to shaft with no offset and no angle here Temporary supports Bolt jackshaft to shaft Dial indicator