Handbook Of Shaft Alignment Episode 1 Part 6 pot

The four bottles of hardener arrived and the pour began in earnest at 1245 h. The procedure was to blend the liquids (epoxy and hardener) for 3 min and then slowly add each bag of aggregate to the mixture as shown in Figure 3.47. Once the fourth bag of aggregate was added, another 2 min of mixing was suggested before the grout should be poured. An electric drill with a mixing blade was used to mix the contents. When the first batch was mixed together, it became apparent that the mixture was very viscous (almost like peanut butter). The drill motor quickly became overloaded and the windings began to overheat and smoke. Another drill motor was at hand so the drills were swapped out and by the second batch, it too became overheated. A larger drill motor was quickly found to handle the mixing with one batch mixed at a time. After adding all the contents, the barrel weighed around 250 lb, a little too heavy for two people to lift and pour directly into the baseplate. Because of the viscosity of the grout, the most effective way to pour was by hand, scooping the grout out of the mixing barrel and then pouring it into a hole as shown in Figure 3.48. After the barrel got half empty, it was light enough to be lifted by two people. We then would fill up a 5 gal bucket and use it to pour while another one or two people would continue to scoop it out with the smaller buckets (which were made with thick plastic 1 gal laundry detergent containers). Thankfully, two barrels were available where one crew would pour the grout whereas another crew would mix the next batch. Initially, each batch took 15 min from the time the mix was started to the time the barrel was empty. After a quick calculation, it was FIGURE 3.46 Protecting the baseplate and surrounding area with plastic covering. FIGURE 3.47 Mixing the grout contents. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 120 29.9.2006 5:53pm 120 Shaft Alignment Handbook, Third Edition conveyed to the work crew that it would take 4 h to finish the pour, far in excess of the cure time so additional personnel were called in to speed up the process as shown in Figure 3.49. About the time the fifth batch was poured, we noticed that the wooden form around the baseplate started to leak as shown in Figure 3.50. Thankfully, we had the foresight to have some duct sealant at hand in the event that this happened and the leaks were plugged as shown in Figure 3.51. It then took approximately 6 min for each batch with bodies scrambling around feverishly mixing and pouring the grout. At 1530 h the final batch pour was made as shown in Figure 3.52. The top plate of the baseplate was designed with a slope toward the pump side so in the event of a water leak, the water could drain off the base to prevent rust from damaging the baseplate. Knowing this, we started the pour at the low end of the baseplate. Once the entire baseplate was filled, the grout began to flow and seek its own level and we noticed that the grout began to swell higher in the pour holes at the low end of the baseplate and drop down at the high end as shown in Figure 3.53. As seen in Figure 3.54, we then topped off the pour holes at the high end hoping that the epoxy would begin to harden at the low end where the pour first began to prevent it from overflowing onto the top of the baseplate. The grout indeed did begin to slowly harden and, in fact, became somewhat like a soft putty so it was decided to begin carving off the grout that had leaked out around the form as shown in Figure 3.55 and Figure 3.56. FIGURE 3.48 Pouring the grout. FIGURE 3.49 More people needed. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 121 29.9.2006 5:53pm Foundations, Baseplates, Installation, and Piping Strain 121 FIGURE 3.50 Grout leak around form. FIGURE 3.51 Plugging the leak with duct sealant. FIGURE 3.52 Finishing the pour. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 122 29.9.2006 5:53pm 122 Shaft Alignment Handbook, Third Edition FIGURE 3.53 Grout began swelling at low end. FIGURE 3.54 Hand packing the grout. FIGURE 3.55 Scraping off the excess grout while still in the putty stage. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 123 29.9.2006 5:53pm Foundations, Baseplates, Installation, and Piping Strain 123 The majority of the work crew then cleaned up and left. Two of us decided to stick around to smooth off the grout at the pour holes as the grout began to harden, which began to quickly accelerate about 1 h after the last pour had been made. Since the chemical reaction of the epoxy grout is exothermic, the baseplate began to get warm, then somewhat hot. We also began to notice that the epoxy began swelling out of all of the pour holes apparently from expansion of the grout during hardening. Surface temperatures of the baseplate were taken with an infrared pyrometer with temperatures ranging from 1278F to 1398F. The epoxy began to harden very quickly around 1700 h, so it was decided to remove the protective plastic sheeting from the top of the baseplate before the epoxy hardened completely. The epoxy had also oozed out of the vent holes and by this time we had to chisel them off as shown in Figure 3.57. Figure 3.58 and Figure 3.59 show the grout pour holes after the epoxy had cured. A fan was placed to begin cooling off the baseplate overnight. The next morning it was decided to take another set of optical alignment measurements on the 8-ft pads to see if the baseplate had stayed in the same position prior to the addition of the grout. Figure 3.60 shows the jig transit and optical scale target on the foot pads. The transit was precision leveled and the line of sight was adjusted to buck back into the same elevation plane by observing the adhesive backed target placed on a nearby building column when the first set of measurements were taken as shown in Figure 3.61. FIGURE 3.56 Scraping off the excess grout while still in the putty stage. FIGURE 3.57 Chiseling off the excess grout. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 124 29.9.2006 5:53pm 124 Shaft Alignment Handbook, Third Edition FIGURE 3.58 Epoxy at grout pour hole. FIGURE 3.59 Baseplate after clean up. FIGURE 3.60 Jig transit set up to observe final elevations on foot pads. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 125 29.9.2006 5:53pm Foundations, Baseplates, Installation, and Piping Strain 125 Figure 3.62 shows the elevation data and the baseplate profiles before and after the grout had hardened. Figure 3.63 shows the pump to be installed and Figure 3.64 the turbine to be installed onto the baseplate. As shown in Figure 3.62, the baseplate had distorted after the grout had been poured. Notice that pad E did not change its position very much after the pour had been made. All of the other pads changed their position with the pads in the center of the baseplate now much lower than either end. The baseplate bowed downwards more in the center, a little at the west end, and virtually none at the east end. The following conclusions can be made: 1. The top surfaces of the four pump foot pads were, and still are not in the same plane. 2. The top surfaces of the four turbine foot pads were, and still are not in the same plane. 3. An 18 in. long precision machinists level is unable to span across two of the pump or turbine foot pads to check for longitudinal and transverse levelness. 4. If a precision machinists level would have been used, the leveling process would have gone on forever. Depending on which pad the machinists level was placed on and what direction it was placed in, the baseplate would have to be re-leveled for each pad. Since the pads are sloped differently, once one pad was precisely leveled, when the machinists level was moved to another pad, it would be out of level. 5. Every effort was made to position the pump foot pads and the turbine foot pads in an averaged level, coplanar, and parallel condition prior to grouting. This was achieved on seven out of the eight foot pads. This could not have been achieved by the leveling jackscrews alone. In several cases, the anchor bolt nuts had to be tightened to bend the baseplate downward to achieve the desired elevation at certain foot pads. There were no jackscrews or anchor bolts located at pad D to distort the baseplate at that position. All anchor bolt nuts were tightened and the adjacent jackscrews tightened to hold the baseplate in its pregrouted position. 6. Every effort was made to follow the installation guidelines set forth by the equipment manufacturers, the grout manufacturer, and the procedures set by API Recommended Practice 686. The objective was to completely fill the baseplate so the grout would bond to the top of the concrete foundation and the underside of the baseplate. By carefully studying the before and after baseplate profiles in Figure 3.62, it becomes obvious that the baseplate changed its shape after the epoxy grout had cured. Our initial FIGURE 3.61 Reference target on building column used to buck in to same elevation. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 126 29.9.2006 5:53pm 126 Shaft Alignment Handbook, Third Edition thoughts were that the baseplate may have moved upward due to the temperature increase from the exothermic reaction of the epoxy. Instead, the opposite happened and it was not a linear move. Upon curing, epoxy grout shrinks. Once the baseplate was filled and the epoxy 10 in. Final pre and post- grout surface elevation and profile Up Side view Bolt plane Bolt plane Bolt plane Bolt plane Bolt plane Bolt plane Pad A Pad B Pad C Pad D Pad E (before grout) Pad G Pad F Pad H Notes: • All elevation data was captured with a optical jig transit • Elevataions were taken on each pad at all four corners • The “shoot for” elevation at the bolt was set at 0.800Љ for the pump pads and 17.800Љ for the turbine pads 0.800 in. (pump) 17.800 in. (turbine) 0.790 in. (pump) 17.790 in. (turbine) 0.810 in. (pump) 17.810 in. (turbine) 0.820 in. (pump) 17.820 in. (turbine) 0.830 in. (pump) 17.830 in. (turbine) 0.840 in. (pump) 17.840 in. (turbine) View looking north Surface with south edge higher Surface with north edge higher Pump Steam turbine 17.805 in. 17.799 in. 17.808 in.17.814 in. 17.859 in. 17.856 in. 17.862 in.17.865 in. 17.827 in. 17.839 in. 17.844 in. 17.831 in. 17.851 in. 17.851 in. 17.840 in. 17.836 in. 0.850 in. 0.857 in. 0.859 in.0.851 in. 0.821 in. 0.823 in. 0.827 in.0.817 in. 0.857 in. 0.859 in. 0.860 in.0.856 in. 0.823 in. 0.825 in. 0.826 in. 0.824 in. Pad A Pad B Pad C Pad D Pad E Pad GPad F Pad H North Top view No. 15 BFW baseplate after grouting Elevations 0.850 in. (pump) 17.850 in. (turbine) 0.860 in. (pump) 17.860 in. (turbine) 0.870 in. (pump) 17.870 in. (turbine) 0.880 in. (pump) 17.880 in. (turbine) 0.890 in. (pump) 17.890 in. (turbine) Pad F Pump Steam turbine 17.800 in. 17.797 in. 17.803 in.17.812 in. 17.833 in. 17.832 in. 17.840 in.17.840 in. 17.787 in. 17.799 in. 17.800 in. 17.788 in. 17.807 in. 17.808 in. 17.796 in. 17.793 in. 0.802 in. 0.809 in. 0.810 in.0.802 in. 0.802 in. 0.800 in. 0.801 in.0.806 in. 0.806 in. 0.811 in. 0.811 in.0.807 in. 0.800 in. 0.799 in. 0.802 in.0.803 in. Pad A Pad B Pad C Pad D Pad E Pad GPad F Pad H North Top view No. 15 BFW baseplate before grouting Pregrout “shoot for” elevation Post-grout best fit curve Pad D Pad B Pad G Pad C Pad H Pad E (after grout) 0.010 in. (10 mils) FIGURE 3.62 (See color insert following page 322.) Elevation data and profiles before and after grout pour. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 127 29.9.2006 5:53pm Foundations, Baseplates, Installation, and Piping Strain 127 bonded to the underside of the top surface of the baseplate, the grout shrunk and bowed the 1=2 in. thick top surface plate downward in the middle despite the fact that there were several structural steel cross members in the baseplate design (see Figure 3.29). Discussions took place on how to fix the out of level and noncoplanar surfaces of the foot pads now that the baseplate was grouted. Suggestions were forwarded to field machine all of the foot pads to make them level and coplanar. If this was to be done, optical alignment equipment should be available to assist in periodically measuring the surfaces that would be machined to achieve level, parallel, and coplanar foot pad surfaces. This however would be a waste of time and money. Getting the foot pads flat and in the same plane assumes that the surfaces on the underside of the pump and turbine are flat and in the same plane. Is this true? No data was taken to verify this despite the comments of one of the equipment manufacturers: ‘‘This couldn’t possibly happen.’’ If you look at the photograph of the turbine in Figure 3.64, you will notice that the turbine supports that will touch pads D and E are L-shaped plates that are axially bolted to the lower turbine casting. If these bolts are loosened in the casting, it is possible that these support plates could be moved due to any clearance between the shank of the bolts and the holes cut into the support plates. It was decided to set the turbine and pump onto the baseplate without machining and check for any soft foot conditions using the procedures described in Chapter 5. Figure 3.65 shows the soft foot map when the turbine and pump were set onto the base. Assuming the undersides of the pump and turbine feet were flat and in the same plane, there should have been very little FIGURE 3.63 Pump being installed on baseplate. FIGURE 3.64 Turbine being installed on baseplate. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 128 29.9.2006 5:53pm 128 Shaft Alignment Handbook, Third Edition (if any) soft foot problems on the pump (pads A, B, F, G). Now look at the soft foot map in Figure 3.65 and observe that the gaps at pad A indicate that the pump foot was not making contact there. Therefore the undersides of the pump feet were not in the same plane. A similar study of the turbine foot pad profile (pads C, D, E, H) and the soft foot map will illustrate that the underside of the turbine feet was also not in the same plane. I have had the opportunity (i.e., been allowed) to use optical alignment equipment a total of four times measuring the four corners of all the foot pads and have seen similar conditions on every baseplate checked this way. I also know that very few baseplate installations are done with this rigorous of a measurement process and that carpenters levels, not machinists levels, are frequently used and that very few people verify that a baseplate is indeed in level after the installers say it was. I am also not sure how often a baseplate was checked for levelness after the grout was poured. It should now become obvious that this may indeed occur very frequently and that foot pads quite likely have a tilt and or twist condition and that the surfaces are not coplanar and that when the machinery is placed onto the uneven, twisted, tilted foot pads, that a flat piece of shim stock will not correct a complex, wedge-shaped gap that will occur. It is difficult, but not impossible to fix this. Chapter 5 will discuss the procedure for doing this. Finally, what effect will a baseplate that is not in level within 2 mils=ft and 5 mils across the entire baseplate have on the successful operation of the machine? If a drive system has a 50 mil slope across the entire baseplate, will the thrust bearings not be able to accept this slight axial force from gravity? I do not prescribe installing baseplate with that radical a slope, but attempting to achieve the tolerances set forth by manufacturers and professional organization seems to be unachievable in the real world. Many may think that what was observed during this particular installation does not occur very frequently, when in fact, it is pro- bably quite common. Perhaps some rethinking needs to be done in soleplate and baseplate installation specifications. 3.3 PROBLEMS TO LOOK FOR IN YOUR FOUNDATIONS AND BASEPLATES A complete visual inspection should be made at least once a year of all rotating equipment foundations, baseplates, piping, etc. Many of these problems are quite obvious as shown in Figure 3.66 through Figure 3.71. Pump Steam turbine Pad A Pad B Pad C Pad D Pad E Pad GPad F Pad H North Top view No. 15 BFW soft foot after grouting 11 12 9 9 2 0 2 0 0 0 2 4 25 29 0 0 0 0 0 0 3 0 8 3 2 0 0 0 Support foot left loose FIGURE 3.65 Soft foot map of pump and turbine. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 129 29.9.2006 5:53pm Foundations, Baseplates, Installation, and Piping Strain 129 [...]... sense of complacency, leading one to believe that accurate shaft alignment is not necessary as ‘‘ the coupling can take care of any misalignment’’ (famous last words) 13 7 Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 13 8 13 8 6 .10 .20 06 5:43pm Shaft Alignment Handbook, Third Edition It is imperative that you can differentiate between coupling tolerances and alignment. .. where an increase in diameter of the external gears will occur As a rule of thumb, 1 mil per inch of external gear tooth diameter can be used as the clearance Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 14 6 14 6 6 .10 .20 06 5:43pm Shaft Alignment Handbook, Third Edition FIGURE 4.3 (continued) Elastomeric flexible couplings [Courtesy of (f) T.B Wood’s and Sons, Chambersburg,... were aligned well within acceptable alignment tolerances and after a 4 6 h run, moved considerably out of alignment Many people assume that when rotating equipment is aligned when it is installed or rebuilt, the alignment will stay stable forever Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 13 6 13 6 29.9.20 06 5:53pm Shaft Alignment Handbook, Third Edition REFERENCES... paid to the form of the tooth itself and the tooth ‘‘profile’’ has progressively evolved through the years to provide minimum wear to the mating surfaces of the internal and external gear sets Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 14 4 14 4 6 .10 .20 06 5:43pm Shaft Alignment Handbook, Third Edition To provide good balance characteristics, the tip of the external... fractional horsepower designs FIGURE 4 .1 Miniature flexible couplings (Courtesy of Guardian Industries, Michigan, IN (b) With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 14 1 6 .10 .20 06 5:43pm Flexible and Rigid Couplings 14 1 4.4 .1 MECHANICALLY FLEXIBLE COUPLING DESIGNS 4.4 .1. 1 Chain Couplings The chain coupling is basically two identical sprockets with... Capacity: up to 70,000 hp Maximum recommended speed: up to 50,000 rpm Shaft bores: up to 30 in Shaft spacing: up to 200 in Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 14 2 14 2 6 .10 .20 06 5:43pm Shaft Alignment Handbook, Third Edition Hub Sleeve Spacer (c) FIGURE 4.2 Mechanically flexible couplings [Courtesy of (a) Browning Mfg., Maysville, KY; (b) Ramsey Products, Charlotte,...Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 13 0 13 0 29.9.20 06 5:53pm Shaft Alignment Handbook, Third Edition FIGURE 3 .66 Fan frame mistakenly designed with no soleplates imbedded in concrete resulting in no contact between underside of frame and top of concrete in the inertia block FIGURE 3 .67 During a torque check on an anchor bolt,... Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 13 9 6 .10 .20 06 5:43pm Flexible and Rigid Couplings 13 9 Temperature range limits How is the coupling attached to the shafts? Size and number of keyways Type and amount of lubricant (if used) Type and design of lubricant seals Actual axial end float on rotors Allowable axial float of shafts Actual... / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 14 8 14 8 6 .10 .20 06 5:43pm Shaft Alignment Handbook, Third Edition FIGURE 4.4 (continued) Disc and diaphragm flexible couplings [Courtesy of (d) Thomas Rexmord, Warren, PA; (e) Dodge-Reliance Electric, Cleveland, OH; (f) Falk Corporation, Milwaukee, WI With permission.] Advantages: Allows freedom of axial movement Capable of. .. teeth diminishes This type of wear is known as ‘‘worm-tracking’’ where gouges occur generally from the base to the tip of the tooth flank The formation of this type of wear pattern will occur when little or no lubrication occurs at Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C004 Final Proof page 14 7 6 .10 .20 06 5:43pm 14 7 Flexible and Rigid Couplings the points of contact between teeth . in .17 . 814 in. 17 .859 in. 17 .8 56 in. 17 . 862 in .17 . 865 in. 17 .827 in. 17 .839 in. 17 .844 in. 17 .8 31 in. 17 .8 51 in. 17 .8 51 in. 17 .840 in. 17 .8 36 in. 0.850 in. 0.857 in. 0.859 in.0.8 51 in. 0.8 21 in F Pump Steam turbine 17 .800 in. 17 .797 in. 17 .803 in .17 . 812 in. 17 .833 in. 17 .832 in. 17 .840 in .17 .840 in. 17 .787 in. 17 .799 in. 17 .800 in. 17 .788 in. 17 .807 in. 17 .808 in. 17 .7 96 in. 17 .793 in. 0.802. 3. 61 Reference target on building column used to buck in to same elevation. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C003 Final Proof page 12 6 29.9.20 06 5:53pm 12 6 Shaft Alignment