Handbook Of Shaft Alignment Episode 2 Part 9 pptx

16.13 ESTABLISHING REFERENCE PLANES Since there is a good possibility that the off-line measurements will be taken at a different time than the running measurements, it is suggested that vertical and lateral reference positions be established. Understand that if you take a set of elevations on scale targets attached to the machinery bearings as shown in Figure 16.46 when the equipment is off-line, then dismantle the optical instrument and tripod, and if you go to set the instrument and tripod backup at a later time, the question now becomes ‘‘what was the original elevation of the instrument when the first set of vertical measurements were taken?’’ One of the primary considerations when using any method where you are observing points on a machine case with respect to a remote observation point is to establish stable, nonmov- ing reference ‘‘planes’’ in the vertical and horizontal directions that enable you to reestablish or ‘‘buck in’’ to that same reference plane for comparison of your off-line and your running measurements. This sounds easy but realistically, this is very difficult to accomplish. Remem- ber you are trying to measure distances as small as 1 mil (0.001 in.). 1. Set the instrument stand at the desired sighting location, attach the alignment scope to the tripod or instrument stand, and level the stand using the “rough” circular bubble level on the tripod (if there is one on the tripod). Insure that the stand is steady and away from heat sources, vibrating floors, and curious people who may want to use the scope to see sunspots. 2. Rotate the scope barrel to line up with two of the four leveling screws and adjust these two leveling screws to roughly center the split coincidence level bubble in the same tilt plane as the two screws that are adjusted as shown. 3. Rotate the scope barrel 90Њ to line up with the other two leveling screws to completely center the bubble in the circular level as shown. 4. If the circular level is still not centered, repeat steps 2 and 3. Adjust these two leveling screws to first adjust the circular level in one direction and then these two screws for the other direction. Split coincidence level Circular level Tilting screw Leveling screw s How to level optical tilting levels and jig transits 10 10 5 5 0 30 50 40 60 10 10 5 5 0 30 50 40 60 FIGURE 16.44 How to level a tilting level or jig transit, parts 1 through 4. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 510 6.10.2006 12:03am 510 Shaft Alignment Handbook, Third Edition The type of reference plane that you establish is somewhat dependent on the period of time between the off-line measurements and the running measurements. If you plan on taking the off-line and running measurements within a 2-h time period, then adhesive-backed targets could be placed on walls or building columns or any fairly stable object. Examples of this are shown in Figure 16.51 through Figure 16.54. If however the time period between off-line and running measurements will be over 2 h or perhaps even days later, you should establish a more stable reference position since building walls or structural steel could very well change shape and position over a long period of time. For vertical elevation measurements, it is suggested that one of the two methods be employed. One way is to fabricate water-cooled pipe stands and attach adhesive-backed targets to them as shown in Figure 16.55. It is recommended that at least two reference points be established, usually one at each end of the drive train. Another way is to use an invar extension rod contacting a tooling ball, which is rigidly attached to the concrete foundation or baseplate or floor as shown in Figure 16.56. For lateral or axial measurements, adhesive-backed targets can be placed on concrete foundations or floors, or better yet, permanently anchored reference targets imbedded in the concrete as shown in Figure 16.57. How to level optical tilting levels and jig transits 8. The last step is to rotate the scope barrel 908 to line up with the two remaining leveling screws yet to be fine adjusted. Follow the same procedure as outlined in steps 6 and 7 above. When these adjustments have been completed, the split coincidence bubble should be coincident when rotating the scope barrel through the entire 3608 of rotation around its azimuth axis. 5. Once again rotate the scope to line up with two of the leveling screws as covered in step 2. Adjust the tilting screw to center the split coincidence level on the side of the scope barrel as shown. 6. Rotate the scope barrel 180Њ and note the position of the two bubble halves. Adjust the two leveling screws in line with the scope barrel so that the gap between the two bubble halves is exactly one half the original gap. 7. At this point, adjust the tilting screw so there is no gap in the two bubble halves. Rotate the scope barrel back 180Њ to its original position and see if the two bubble halves are still coincident (i.e., no gap). If they are not adjust the two leveling screws and the tilting level screw again as shown and rotate the scope barrel back 180Њ until there is no gap when swinging back and forth through the half circle. The two leveling screws should be snug but not so tight as to warp the mounting frame. 10 10 5 5 0 30 50 40 60 10 10 5 5 0 30 50 40 60 10 10 5 5 0 30 50 40 60 10 10 5 5 0 30 50 40 60 Gap Half gap No gap Gap Half gap No gap FIGURE 16.45 How to level a tilting level or jig transit, parts 5 through 8. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 511 6.10.2006 12:03am Measuring and Compensating for Off-Line 511 Key considerations for capturing good readings: . Provide stable platforms for the optical scale targets . Establish several (minimum of two, three suggested) vertical, lateral, and axial reference positions to ‘‘buck’’ back into . Scale target should be located as close as possible to the bearings since we are trying to determine where the shafts are going (if the bearing moves, the shaft is sure to move with it) . Magnetic base holders should be used to hold the scale targets insuring a stable target position . Clamp on circular level bubble sets should be used on the scale target to insure scale targets are in a pure vertical position 1. Check calibration of the instrument (see Peg Test). 2. Select suitable scale positions at the inboard and outboard ends of each piece of machinery in the drive train. The “platforms” that the scale targets will be sitting on should be stable and slightly below the centerline of rotation and usually near the bearings.You can use 2 in. 3 2 in. pieces of angle bearing housing.Try to insure that the surface that the scale targets will sit on is relatively level and flat. It is also advisable to install reference stands at each end of the drive train and affix a “stick-um” crosshair target to the reference stand.You can make these stands out of 3 in. or 4 in. pipe, fill them with a water–glycol or antifreeze solution, insulate the pipe, bolt or clamp them to the frame or floor, and monitor the water temperature to insure thermal stability. 3. Set the optical instrument and stand at some remote reference point away from the drive train where a stable point in space can be established but close enough to maintain the maximum possible accuracy of the readings. 4. Accurately level the instrument and take a set of readings at each target scale mounted on the machinery when it is “off-line” (i.e., not running) occasionally checking back to the reference targets at each end of the drive train to insure that you are maintaining the same vertical elevation (i.e., shooting through the same horizontal plane). 5. Run the machinery at normal conditions and allow the equipment to stabilize its position (this can take hours or even days). 6. Check the level accuracy and take a similar set of readings at each target scale occasionally checking back to the reference targets at each end of the drive train to insure that you are maintaining the same vertical elevation. 7. Compare the off-line set of readings to the running set of readings to determine the amount and direction of the movement of each scale. Optical alignment OL2R procedure for vertical (up and down) measurements 12 3 2 468 2 4 68 2 468 Optical Scale Target 12 3 2 4 68 2 4 68 2 4 68 Optical Scale Target 12 3 2 4 68 2 4 68 2 4 68 Optical Scale Target 12 3 2 4 68 2 4 68 2 4 68 Optical Scale Target Reference stand Reference stand Scale targets FIGURE 16.46 How to take optical vertical OL2R measurements. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 512 6.10.2006 12:03am 512 Shaft Alignment Handbook, Third Edition . If possible, try to keep the scale targets in place from OL2R conditions. . Keep the scale target holding platforms clean. . Move slowly when working around the tilting level or jig transit and stand (if your foot or arm bumped the stand, it is probably not in the level or in the same vertical or horizontal plane any more). . Readings should be taken at night when equipment is located outdoors to prevent thermal instability of the tripod or stand when the sun heats or cools the stand. 1. Check calibration of the jig transit (see Peg Test). Two people are required to do this procedure—the scale target holding person and the observer. 2. Select suitable scale “anchor” points at the inboard and outboard ends of each piece of machinery in the drive train. The points or “anchors” that the scale targets (and probably extension rods) will be touching should be stable and directly above or below the centerline of rotation and usually near or at the bearings. You can have tooling balls firmly affixed to the machine care or bearing housing as the “anchor” points to hold the scale target against for reference. 3. Set the jig transit and stand at some position along one side of the drive train where a stable point in space can be established insuring that measurements can be taken at each bearing location when the scale target or extension rod is placed at each “anchor” point at every bearing location. Orient the optical micrometer on the scope barrel to allow variation in the position of the vertical crosshair when the micrometer barrel is rotated. 4. Accurately level the instrument, then loosen the vertical sweep axis screw allowing the scope to tilt up and down. Affix several (at least two) adhesive crosshair targets to the foundation or floor along the full length of the drive train establishing a vertical reference line or plane. Take a set of readings at each bearing location by holding the scale target or extension rod when placed at each “anchor” point when the machinery is “off-line” (see “waving scales”) occasionally checking back to the adhesive crosshair targets attached to the foundation or floor to insure that you are maintaining the same horizontal position (i.e., keeping in the same vertical reference plane). 5. Run the machinery at normal conditions and allow the equipment to stabilize its position (this can take hours or even days). 6. Check the level of accuracy and take a similar set of readings at each bearing location occasionally checking back to the adhesive crosshair targets attached to the foundation or floor to insure that you are maintaining the same horizontal position. 7. Compare the off-line set of readings to the running set of readings to determine the amount and direction of the movement of each scale target and bearing location. Optical alignment OL2R procedure for horizontal (side-to-side) measurements 12 3 24 6 8 24 6 8 24 6 8 Optical Scale Target 12 3 24 6 8 24 6 8 24 6 8 Optical Scale Target 12 3 2 4 68 2 468 2 4 68 Optical Scale Target 12 3 2 4 68 2 468 2 468 Optical Scale Target Jig transit “Anchor” points Scale targets Line of sight Extension rod (invar) Top view Reference targets 10 10 5 5 0 30 50 40 60 FIGURE 16.47 How to take optical horizontal (side-to-side) OL2R measurements. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 513 6.10.2006 12:03am Measuring and Compensating for Off-Line 513 . Capture a set of readings from OL2R conditions and another set of readings from R2OL conditions to determine if there is a consistent pattern of movement. . Several sets of measurements (minimum of two, three suggested) should be taken for the off-line measurements and also for the running measurements to verify that the equip- ment is in both a stable off-line and stable running position. Advantages: . Extreme accuracy possible (1–2 arc seconds) with a precisely leveled and calibrated instrument . Excellent repeatability if instrument is properly calibrated, consistent positioning of scale targets is done, precise leveling is achieved, and stable reference points have been established Jig transit “Anchor” point Scale target Line of sight Top view 12 3 2468 2468 2468 Optical Scale Target “Waving” scales To insure that accurate readings are taken for the side-to-side measurements, the scale target must be at a 908 angle to the line of sight. By “waving” the scale target toward and away from the observer (jig transit), a precise 908 angle will be obtained when the minimum reading is observed. 90Њ angle required for accurate reading 10 10 5 5 0 30 50 40 60 FIGURE 16.48 How to take accurate optical horizontal measurements. FIGURE 16.49 Jig transit and scale target on outboard pump bearing for lateral measurement. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 514 6.10.2006 12:03am 514 Shaft Alignment Handbook, Third Edition . Tremendous versatility and range of possible measurement points . Measuring instruments can usually be placed away from heat sources Disadvantages: . Knowledgeable, patient, and dedicated personnel required for successful measurements and evaluation of data. . If the machinery is vibrating excessively, it appears that the scale targets cannot be focused when taking the running measurements (a strobe light could be used to measure the high and low points of the target by tuning the strobe slightly off the vibration frequency of the object it is sitting on however). . Scale and reference target holding devices usually need to be custom fabricated and carefully placed to insure long-term stable position. . Instrumentation, targets, and fixturing relatively expensive. 16.14 ALIGNMENT BARS WITH PROXIMITY PROBES This method falls into the category of observing movement of one machine case with respect to a position on the other machine case. This device was invented in the early 1970s by Ray Dodd while working at Chevron. The machinery alignment bar OL2R system is based on the principle of the reverse indicator method explained in Chapter 7. Two ‘‘bars’’ are used, a ‘‘probe bar’’ and a ‘‘target bar.’’ The probe bar is attached near the inboard (coupling end) bearing as close as possible to the centerline of rotation on one machine case. The target bar is attached near the inboard (coupling end) bearing as close as possible to the centerline of rotation on the other machine case. The probe bar and target bar ‘‘shadow’’ each other but they do not touch. Four proximity probes are attached to the probe bar, two vertically oriented probes and two horizontally oriented probes. These probe sets are mounted at two locations along the length of the bar, which observe two positions on the FIGURE 16.50 Holding scale target with invar rod extension for lateral measurement. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 515 6.10.2006 12:03am Measuring and Compensating for Off-Line 515 FIGURE 16.51 Adhesive-backed target attached to I-beam. FIGURE 16.52 Adhesive-backed target attached to I-beam. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 516 6.10.2006 12:03am 516 Shaft Alignment Handbook, Third Edition FIGURE 16.53 Transit with scale target in background. FIGURE 16.54 Adhesive-backed target attached to wall. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 517 6.10.2006 12:03am Measuring and Compensating for Off-Line 517 target bar. The targets could be blocks of steel attached to tubing or they could be the target bar surface itself as shown in Figure 16.58 and Figure 16.59. Before starting the drive train when the machinery is off-line and in a stable position, a set of gap readings are taken on each of the two vertically oriented probes and each of the two horizontally oriented probes. The drive system is then started up and operated under normal running conditions until the probe gaps have stabilized. Relative machinery casing movement can be determined by comparing the gaps on each probe before and after the equipment is running. Strip chart recorders (or similar devices) can be set up to monitor the rate of change of gap during warm-up and on-line operating conditions and to see when the positions have stabilized (Figure 16.60). Key considerations for capturing good readings: . The probe and target bars should be attached to each machine case as close as possible to the centerlines of rotation to accurately determine shaft motion, not casing expansion or bearing housing warpage (see Figure 16.26). . Important to have target surfaces at precise 908 angles to the proximity probes. . The bars can be positioned inside or outside the coupling guard or shroud with precau- tions taken to prevent excessive vibration of the bars from coupling windage if mounted inside the guard. . Capture a set of readings from OL2R conditions and another set of readings from R2OL conditions to determine if there is a consistent pattern of movement. Floor Machinery foundation Anchor bolts Drain 3 in. or 4 in. pipe filled with water–glycol solution and temperature monitored for stability Reference target Insulation FIGURE 16.55 Water-filled pipe reference stand. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 518 6.10.2006 12:03am 518 Shaft Alignment Handbook, Third Edition Floor Reference tooling ball Invar extension rod assembly Scale target 24 68 0 000 0 1 24 68 11111 2 24 68 2222 2 3 24 68 33 3 3 3 4 24 68 44 4 4 4 5 24 68 55555 6 24 68 6666 6 7 24 68 77777 8 24 68 8 888 8 9 24 68 99999 10 Machinery foundation FIGURE 16.56 Invar rod and scale contacting tooling ball on foundation. FIGURE 16.57 Permanent floor target. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 519 6.10.2006 12:03am Measuring and Compensating for Off-Line 519 [...]... housing of driver machine Eddy probe (2 of 4) Indicator block Probe mount Stiffener Eddy probe driver (1 of 4) Airframe tubing Base mounted through bracket to bearing housing of driven machine 520 (a) Extension cable (1 of 4) Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 520 6.10 .20 06 12: 03am Shaft Alignment Handbook, Third Edition Flexible coupling and shaft ends... centerlines of rotation to accurately determine shaft motion, not casing expansion or bearing housing warpage FIGURE 16.68 Plug in back zeroing laser-target mounts (Courtesy Murray & Garig Tool Works, Baytown, TX With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 528 6.10 .20 06 12: 03am 528 Shaft Alignment Handbook, Third Edition FIGURE 16. 69 Close-up of four-axis... set of readings from R2OL conditions to determine if there is a consistent pattern of movement Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 534 6.10 .20 06 12: 03am 534 Shaft Alignment Handbook, Third Edition FIGURE 16.77 BRTC system measuring OL2R movement of steam turbine and pump Advantages: Fairly accurate measurements possible with proper setup Capable of measuring... Alignment bar arrangements (Upper diagram: Courtesy of Scientific Atlanta=SKF Condition Monitoring, San Diego, CA With permission.) (b) Proximity probe The target bar can be attached to either the driver or the driven unit Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 521 6.10 .20 06 12: 03am Measuring and Compensating for Off-Line 521 Piotrowski / Shaft Alignment Handbook, ... movement of steam turbine and compressor (Courtesy Murray & Garig Tool Works, Baytown, TX With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 533 6.10 .20 06 12: 03am 533 Measuring and Compensating for Off-Line Off-line machinery positions Running machinery positions Center of inboard foot bolt Center of inboard foot bolt Backside of ball Center of Center of Backside... sets of laser–detector equipment FIGURE 16. 62 Laser–detector–prism systems setup on custom mounts measuring gear and compressor OL2R movement Alignment bar setup also used for comparison Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 525 6.10 .20 06 12: 03am Measuring and Compensating for Off-Line 525 ¨ FIGURE 16.63 Permalign systems mounted across coupling (Courtesy of. .. that very few people have tried to use their systems for this purpose The underlying Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 524 6.10 .20 06 12: 03am 524 Shaft Alignment Handbook, Third Edition FIGURE 16.61 Basic setup of laser–detector systems used to measure OL2R movement reluctance seems to originate from the difficulty in mounting the lasers and detectors... Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 522 6.10 .20 06 12: 03am 522 Shaft Alignment Handbook, Third Edition Probe bar “H”-shaped base to allow for positioning the bar in the up Angle iron and down direction Target bar “H”-shaped base to allow for positioning the bar in the sideways direction End view of bars and probes FIGURE 16. 59 Fabricated alignment bar design Advantages: Fairly... brackets and laser–detector mounted across coupling (Courtesy of ¨ Pruftechnik, Ismaning, Germany With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 526 6.10 .20 06 12: 03am 526 Shaft Alignment Handbook, Third Edition FIGURE 16.65 Permalign M3 brackets and laser–detector mounted across coupling (Courtesy of ¨ Pruftechnik, Ismaning, Germany With permission.) laser–detector... installed on each machine case as close as possible to the centerline of rotation Possibility of inaccurate measurements due to uneven thermal distortion of machine case where the holding fixtures are attached Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 530 6.10 .20 06 12: 03am 530 Shaft Alignment Handbook, Third Edition File Edit Show Unit Moues Shortcuts Overlay . assembly Scale target 24 68 0 000 0 1 24 68 11111 2 24 68 22 22 2 3 24 68 33 3 3 3 4 24 68 44 4 4 4 5 24 68 55555 6 24 68 6666 6 7 24 68 77777 8 24 68 8 888 8 9 24 68 99 999 10 Machinery foundation FIGURE. of bars and probes Angle iron FIGURE 16. 59 Fabricated alignment bar design. Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C016 Final Proof page 522 6.10 .20 06 12: 03am 522 Shaft Alignment. down) measurements 12 3 2 468 2 4 68 2 468 Optical Scale Target 12 3 2 4 68 2 4 68 2 4 68 Optical Scale Target 12 3 2 4 68 2 4 68 2 4 68 Optical Scale Target 12 3 2 4 68 2 4 68 2 4 68 Optical Scale Target Reference stand Reference stand Scale