Optical Alignment, Thermal Growth, & Machinery Movement

Optical Alignment, Thermal Growth, & Machinery Movement
Presented For: The Vibration Institute, February 17th, By: Stanley R. Bognatz, P.E. President © 2007 M&B Engineered Solutions, Inc. 1

Optical Alignment, Thermal Growth & Machinery Movement
Introduction Optical Alignment, Thermal Growth & Machinery Movement Our customers’ often seek help achieving precision alignment of their critical machinery when ‘standard’ alignment techniques do not provide satisfactory operation. While helping them achieve the ‘simple’ goal of good hot alignment, we’ve identified many mechanical issues using Optical Alignment (“OA”) that were not intuitive to those involved, and were not previously solved using vibration analysis or other techniques. We would like to share some OA background with you, and how we apply OA to optimize shaft alignment and eliminate machinery problems. Notes © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 2

Basic Shaft Alignment Optical Alignment, Thermal Growth & Machinery Movement How do we define the (mis)alignment of two machine shafts? Parallel misalignment: coupling ‘rim’ offset between two shaft centerlines Angular misalignment: coupling ‘face’ deviation from parallel Combined – the usual field condition…. Notes: Parallel & Angular misalignment are always a concern, regardless of coupling design or coupling span. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 3

Alignment Factors Optical Alignment, Thermal Growth & Machinery Movement How accurate do we need to be? What factors might you consider? More Critical: Less Critical: High speed (=> 1,800 rpm) Low speed (< 1,800 rpm) Rigid couplings Geared Couplings Disc-pack couplings (for offset) Flexible Couplings Short coupling spans Long coupling spans What criteria do you have? Notes: No mention is made of bearing design, but it will be in the next slide. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 4

Alignment Criteria Optical Alignment, Thermal Growth & Machinery Movement The Alignment Tolerance Chart ties speed, coupling span, and misalignment in the horizontal & vertical directions together to assess alignment accuracy. Shaft deviation is calculated for each side of the coupling (h & v) and plotted as a function of speed to determine if alignment is required. We can see that at 3,600 rpm, deviation much beyond 1 mil/inch should be realigned. Notes: H & V are the horizontal & vertical offsets on 1 side of coupling. P.T. is the Power Transmission distance. A shaft deviation value should be evaluated for each side of the coupling, as one side will usually show more misalignment (greater offsets) than the other. Note that bearing & coupling design are not EXPLICITY taken into account. However, the above values will produce excellent alignment and reliability regardless of coupling & bearing design. Ludeca: Also, when determining what tolerances to use for shaft alignment, make sure to take into account information provided by both the coupling manufacturer and equipment manufacturer. The coupling manufacturer may state that the coupling can withstand far more misalignment than what the equipment manufacturer suggests for their machines. However, when shafts are not properly aligned, vibration that is sustainable by the coupling will pass directly into the machines’ bearings and mechanical seals. These components may not be able to withstand the same forces that the coupling can, and therefore deteriorate or fail prematurely © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 5

Alignment Accuracy Optical Alignment, Thermal Growth & Machinery Movement So, once again: How accurate does our alignment need to be? To muddy the water just a bit more: What is the point in setting a cold shaft alignment within 0.002" if adjacent bearing housings move 10 – 20 mils (or more!) in different directions due to thermal growth and static deflection? If we set a ‘perfect’ cold alignment, with the shafts collinear, it is a “sure bet” that thermal growth and static deflection will ruin our alignment when the machine is operating. This is where Optical Alignment will provide significant improvement in our operating (hot) alignment accuracy. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 6

What is ‘Optical Alignment’?
Optical Alignment, Thermal Growth & Machinery Movement “OA” - The use of high-precision optical instruments (jig transits, sight levels, alignment telescopes) and special tooling to measure the relative alignment of machinery. OA can help us answer these questions with high accuracy: Is it straight? Is it level? Is it plumb? Is it square? Applications of OA include: Align bearing & seal bores Align diaphragms Set rolls parallel Level base & sole plates Check flatness Align & level machine cases Measure thermal growth Measure static deflection Notes: The application of “straight, level, plumb & square” is only limited by the user’s imagination in defining alignment measurements. With the right application of measurements and references, we can setup virtually any machine. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 7

Why Optics? Optical Alignment, Thermal Growth & Machinery Movement What advantages does optical equipment have for determining “Is it Straight, Level, Plumb & Square?” Measurement flexibility – horizontal; vertical; axial; bores; casings; split-lines; diaphragms; rolls; baseplates; soleplates; foundations; rolls; etc. Many measurements quickly References (Benchmarks) allow absolute comparison of components Easy to setup in multiple locations around any machine Easily portable Excellent repeatability between surveys Excellent accuracy Notes: ______________________________________________________________ © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 8

Optical Alignment Equipment
Optical Alignment, Thermal Growth & Machinery Movement Several essential pieces of gear comprise a typical OA kit: Jig transits; alignment telescopes Precision Scales Scale Levels Invar Kit Tripods ‘Tubes’ Cross-slides Mounting Hardware / Tooling Benchmarks Tool kit Notes: ______________________________________________________________ © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 9

Brunson 76-RH Jig Transit
Optical Alignment, Thermal Growth & Machinery Movement Brunson 76-RH Jig Transit key features & functions: Main Telescope: 30X magnification; focus 2” to Infinity (and beyond) Main scope sweeps horizontal & vertical planes Fine-motion tangent screws for adjustment Cross Telescope: 45X magnification; provides sights at precise right angles to the main scope Coincidence Level: precision leveling (1 arc-sec) Optical Micrometer: offset measurements (0.001”) Extreme Accuracy - bearing runout < ” Calibration can be verified on-site for every job SRB Notes: We like to talk a bit about what makes optical measurements accurate, and why this equipment is so helpful in machinery alignment and problem solving. Brunson: By simply shifting from one eyepiece to the other, operators can establish or verify their position relative to the basic references only one technician, where previously two were required. The 76-RH is the undisputed "workhorse" in optical alignment, providing tremendous flexibility with substantial time and manpower savings. Focusing Range: 2 inches to infinity Resolution: 3.9 arcseconds (with 190 mic???) Reticle: Glass, filar/bi-filar pattern (others available) Field of View: 1 degree Image: Erect Optics: Low reflective, protective coating ______________________________________________________________ Focusing Range: Infinity (fixed on cross scope) Approximate Weight: Instrument, 34 pounds; instrument and case, 54 pounds; shipping, 56 pounds © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 10

Coincidence Level Optical Alignment, Thermal Growth & Machinery Movement The coincidence level system is the key to the jig transit’s accuracy. Vertical tangent screw on transit subtly tilts the telescope to dead-level the line of sight. When viewed through the turret, both ends of the coincidence level ‘bubble’ are optically ‘folded’ and brought together, side-by-side, using a 2.5X mirror path. The human eye is very good at evaluating coincident patterns and can detect the tiniest deviation from level. Notes: Turret has with 2½X magnification How sensitive is this system? We can easily detect 1 arc-sec of tilt 1 arc-sec = The width of dime viewed from 1 ¼ miles away In practical terms, 1 arc-sec = ” (1.3 mils) at 17 feet © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 11

Optical Micrometer Optical Alignment, Thermal Growth & Machinery Movement Optical Mics and Scales provide the means to make measurements…. The “mic” uses a drum graduated in 0.001” increments to act as a vernier when reading scales For example, after sighting a scale between 17.4” and 17.5”, the mic is adjusted to move the reticle to 17.4, and the amount moved is read from the drum, 0.040”, This gives a reading of ” Notes: Optical mics and coincidence levels are found on both jig transits and sight levels. Alignment telescopes will have 2 optical mics for simultaneous horizontal & vertical readings. Brunson stuff: This is an optical micrometer which contains a block of glass that when rotated, moves the incoming image up and down by known amounts. It’s one of those really cool things from physics. Anyway, all you have to do is turn the graduated drum on the micrometer, which offsets the image and makes it appear to move up and down, until the crosshairs appear to be right in line with the 3.2 mark on the scale. Then you look at the graduated drum on the micrometer to see how much you moved the image. If you moved it, say, 0.036", then you know that the line of sight is precisely 3.2 (as read from the scale) (as read from the micrometer) = 3.236" above the table. Cool! Now move the scale somewhere else on the table and take another reading. This time, using the same process, you take a reading of 3.276", which you can immediately calculate is a point 0.040" below the first reading (yes, below, because the scale had to go down by 0.040" to get a reading of – the line of sight stayed level). You can take any number of additional points to determine whether the table is level – or whether it’s even flat, which is a different question. This process is essentially how all measurements are made using Optical Tooling instruments, whether they’re made up, down, or sideways______________________________________________________________ ______________________________________________________________ © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 12

Optical Scales Optical Alignment, Thermal Growth & Machinery Movement A little bit more sophisticated than the old wooden ruler… Hardened tool steel Matte white surface Glare reducing top-coat Various sizes, 3”, 10”, 20”, 40” Graduated in inches and tenths Accuracy +/ ” Varying ‘tic’ spacing for different sight distances 0.004” (closest) 0.010” 0.025” 0.060” (farthest) Notes: A pattern of four distinct paired-line targets (across the width of each scale), appearing as adjacent sets of bars or blocks, repeats over the length of the scale every 0.100" or 0.2 mm, depending upon whether the scale is English or metric. The filar/bi-filar reticle in our instruments makes it possible to position the line of sight (using an optical micrometer) accurately between any of the paired line targets on the scale. When close up, the smallest pair of "tick" marks is used. As viewing distance increases, the progressively wider paired-line spacings are used. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 13

Invar Kits Optical Alignment, Thermal Growth & Machinery Movement Invar comes in various lengths, and is assembled as needed to mount scales in the desired line-of-sight. Invar’s extremely low coefficient of thermal expansion makes it perfect for consistent measurements in any machinery environment. Compare growths of a 5’ rod over a 30°F ΔT: Aluminum: ” Steel: ” Invar: ” !! Notes: the thermal coefficient of expansion of Invar is 0.68 x 10-6 in./in.F over a range of 0-200F. Compare this to steel at 6.8 x 10-6 in/in/degF. Tolerance: +/ ” per tube, std. Total stack-up error per kit +/ ” © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 14

Tripods, Tubes & Cross-Slides
Optical Alignment, Thermal Growth & Machinery Movement Stable bases are critical for reliable data. Quickset’s ‘Hercules’ tripods have proven rock solid, light weight & portable. The tripod’s elevator lets us adjust scope height, and ‘tubes’ allow us to reach high locations. Cross-slides provide lateral move-ment to let us ‘buck-in’ the instrument to a desired line-of-sight. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 15

OA Applications Optical Alignment, Thermal Growth & Machinery Movement Internal alignment of crankcase bearings (bore alignment) Alignment of gearbox bearings to extruder bore Brunson Notes: Measuring bearing alignment in an engine block and evaluating for straightness is another easy task with an instrument like the 2022. Notice that the application is very similar to a bore alignment (described above). Again, the instrument is positioned so that the line of sight is coincident with some known or desired reference. This time, a target placed at various bearing supports in the engine block and measurements relative to the instrument’s straight line of sight are made. Horizontal and vertical profiles can be generated for each bearing housing to determine alignment. We supply a large variety of targeting to facilitate many different types of alignments. Chances are, we've seen something like your application before, and have a target that is just right. The 2022 Alignment Telescope is also great for measuring the alignment of an extruder tube relative to a gear box housing. To accomplish this, targets are mounted in the gear box so that the 2022 can be positioned exactly on the gear box's critical line. Once the 2022 has been positioned, it optically represents the gear box's centerline, and measurements can be taken on work targets (or one work target which is moved to several different positions) in the extruder tube to determine if the tube is in alignment with the gear box. Deviations from the centerline can be quantified and technicians can be told exactly how much to move machine components to bring everything back into alignment. In fact, an instrument operator can observe the progress while adjustments to the machinery are being made. Alignments like this are crucial for preventing damage to a gear box. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 16

OA Applications Optical Alignment, Thermal Growth & Machinery Movement Establishing parallel gearbox bearing bores Setting parallel roll position (& heights) in paper / steel mills Brunson Notes: Checking parallelism of bearings in a gearbox is also a simple task using optical equipment. In this example, a 76-RH transit is used to establish the centerline of the first pair of bearings (at left in illustration). By using "bore targets" or some other appropriate targeting, the line of sight of this transit's main telescope is positioned directly on a line between the two bearing centerlines. Then, a second 76-RH is roughly positioned so that it points down the centerline of a second pair of bearings. The reticle in the cross-axis telescope of the first 76-RH is illuminated, and the cross-axis telescope on the second transit is bought into collimation with the first. This makes the main telescopes of both instruments precisely parallel, and the second (or subsequent) pairs of bearings can be evaluated for parallelism to the first. Let's say that you need to evaluate a number of machine components to make sure they are all parallel (like rolls in a rolling mill). One way to approach the job would be like this: Establish a reference line running parallel to the entire machine (so that ideally, all rollers should be perpendicular to this line). Set up an instrument to turn a precise right angle from this reference line. Measure how parallel each roll is, using the instrument at right angles to the reference line. Let's take a close look at each of these steps. There are several ways to establish the reference line which runs parallel to the entire machine, but let's use a somewhat typical situation. Suppose that an "offset centerline" is marked by floor monuments near the machine. This is a line which is parallel to the machine centerline, which was established by floor markers at some time in the past. Picture a vertical plane rising up through these floor markers. We can set up a model 76-RH transit so that it is directly in line with this vertical plane, and pointing in the direction established by the floor markers. We'll call this instrument "A". When this is done, we have one transit whose line of sight can be used as the reference because it has been set exactly parallel to the machine centerline. We set the focus of this instrument at infinity and turn on the reticle illumination light. Why do we do this? Stay tuned..... Next, we set up another model 76-RH transit somewhere near one of the rolls that we want to align. We'll call this one "B". Remember that the 76-RH has a horizontal cross-axis telescope permanently focused at infinity, which is mounted exactly perpendicular to the main telescope. When we point the main telescope of instrument B toward the rolls, its cross telescope will be pointing back at transit A. Since we focused A's telescope at infinity and illuminated its reticle, we can collimate B's cross-telescope on the reticle in A's main telescope. This alignment process causes the main telescope of B to become exactly perpendicular to the main telescope of A. Accordingly, the main telescope of instrument B can now sweep a plane which is perpendicular to the machine centerline. We then hold an optical tooling scale on the side of the roll (near the end), oriented horizontally. Scale bubble levels help us to know that the scale is actually horizontal and that it is placed properly on the roll. We take a measurement on this scale using the micrometer on instrument B. Then we move the scale to the other end of the roll and repeat the process. Taking measurements on each end of the roll will reveal the degree to which the roll is not parallel to B's line of sight. We know that the roll must be parallel to B's line of sight in order to be perpendicular to the machine centerline. When we are finished with this roll, we simply move transit B over to the next roll. Sometimes more than one roll can be measured without moving the instrument (ex., measuring the right side of one roll and the left side of another). Since A is still aligned with the offset centerline, all we have to do is to set up B in another position and re-collimate to A. In this manner you can check an entire row of rolls or other components for parallelism to any given reference. (Note: There are other ways to establish the original reference line. For example, you could perform the measurement process in reverse, setting transit B parallel to the first roll. Then you could set transit A perpendicular to B, and use it as the reference for measurement of subsequent rolls. After you measure all the rolls, you would be able to determine which ones should be adjusted.) © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 17

OA Applications Optical Alignment, Thermal Growth & Machinery Movement Plumbing columns / surfaces; measuring horizontal deflection Leveling; checking flatness; measuring vertical deflection Notes: Making things vertical is almost as easy as making them horizontal. To do this job, however, you have to use a transit rather than a level. A procedure called "precision plumbing" can be performed on any transit which has been mounted on a stable stand or other foundation. This procedure allows the operator to ensure that the vertical spindle of the transit is perfectly vertical - as in "exactly parallel to gravity", not just pointing generally "up and down". After a transit has been precision-plumbed, we know that the telescope will rotate through a vertical plane, regardless of what azimuth (horizontal) direction that plane is oriented. We then must bring the transit into a position where it is nominally parallel to the surface that we're trying to measure. We do this using a simple procedure called "bucking in". The illustration shows the use of a transit to plumb a machine tool column (or any vertical surface). In this application, the transit sweeps a vertical plane through scales that are affixed horizontally to the machine column. The measurements are relative to this vertical optical reference plane, and we will quickly know whether the machine is vertical or not, and how much out of plumb it is. That is, if all of the scales give us exactly the same reading, we know that the machine surface is parallel to our vertical plane. But if they're not, we can tell how much the surface is leaning one way or the other, and in fact whether the surface is flat or curved. The observed measurements can be used to plumb the machine component. The Brunson model level, also referred to as a precision sight level, builds upon the construction and design principles of the alignment telescopes. Precision sight levels can perform many of the same operations as both the 2062 and 2022 alignment telescopes. However, they are optimized for leveling operations, having the additional ability to sweep a horizontal plane and perform precision leveling operations using a built-in split-bubble vial. In this example, a precision sight level is mounted on a stable stand, and rough-leveled using the attached bull's eye vial. Then, the main leveling screw is moved so that the telescope is brought exactly level. This is determined by watching a magnified split-bubble image of a very precise vial mounted on the side of the instrument. This fine-threaded leveling screw makes it very easy to bring the telescope into a level position within 1 arcsecond. Once the instrument is established as level, scales are mounted in various positions on the machine bed or foundation. It is equally easy to use one scale and move it around to the positions of interest. Readings to the nearest 0.001" inch or 0.03 mm are taken at each scale position using the precision sight level's micrometer as a vernier. Scale readings from the different positions are then compared to determine whether the platform is out of level, in what direction is it out of level, and by how much. Again, adjustments may be made to the bed while someone observes the bed's movement by watching the scales through the precision level's telescope in order to give immediate feedback to the person doing the adjustment. Once the bed has been nominally leveled, a thorough evaluation may be made to see if the bed is flat, or whether there is any undesired sag or curvature. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 18

OA Applications Optical Alignment, Thermal Growth & Machinery Movement The measuring of horizontal and vertical movement forms the basis for determining how machinery moves from off-line to running conditions. By measuring how each bearing in a machine moves, we can determine exactly how the ‘cold’ alignment should offset to produce an accurate ‘hot’ alignment when operating. This movement is sometimes referred to as “OL2R”, but most folks lump it into the term “Thermal Growth”. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 19

Thermal Growth is often just considered to be the Vertical change in bearing or shaft position due to temperature changes (ΔT) in the machine casing, bearing supports, and foundations. Movement due to ΔT can be easily calculated. For steel, a coefficient of thermal expansion of {6.8 x 10-6 in / in / °F} is typically used. For example, a bearing pedestal 30” tall that was 45° hotter when the machine was running would ‘grow’ by: (6.8x10-6) x 30 x 45 = ”, or 9.2 mils (not too bad…) But, if the ΔT were 150°F, the change would be: (6.8x10-6) x 30 x 150 = ”, or 30.6 mils hmmm…so much for our cold alignment Do you know of any machines operating 50° or more above ambient? What effect is that ΔT likely having on the alignment? SRB Notes: Thermal growth © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 20

Static Deflection Optical Alignment, Thermal Growth & Machinery Movement The Thermal Growth on the previous slide only considered vertical calculations. This is how many machinery OEMs derive their cold alignment offsets. And while it is a good starting point, it is only part of the equation. We should also consider the horizontal bearing housing movement. Machine casings will often show equal horizontal thermal expansion on both sides of a bearing due to casing symmetry. However, many (most?) machines also exhibit static deflection due to the effects of torque transmission. Other issues such as grout deterioration, pedestal or foundation flexure, and soft-foot will compound both the horizontal and vertical movements seen while operating. It is easy to see how our good, cold alignment can quickly become unacceptable while the machine is operating. This is where Optical Alignment can provide us with the measurements to properly align the machinery. SRB Notes: Thermal growth © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 21

Case Study #1 – A Tale of 2 Boiler Feed Pumps
Optical Alignment, Thermal Growth & Machinery Movement Or, One of these things is not like the other…. Machinery Configuration Motor: 3,585 rpm ; 4,500 HP Cplg: Disc-Pack Pump: 11 Stage; 2030 gpm; 7520’ hd. Customer Problem: Poor reliability on #1 BFP inboard pump seals (~6 months) Notes: Be sure to explain H-A, H-B are for horizontal measurements; V-A, etc. are for vertical measurements. The same benchmarks can be used for both types of readings. Dowel pins were mounted, 2 on each bearing to ensure data could be averaged about the shaft centerline. Diagram showing dowel-pin measurement points (1,2,3, etc.), benchmarks (BM-x), and jig-transit locations used. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 22

Case Study #1, continued Optical Alignment, Thermal Growth & Machinery Movement Alignment Study Results – #1 BFP Vertical Data The pump pivoted very nearly about the outboard pedestal, causing the inboard bearing to go upward, likely due to pipe strain, thus loading the bearing & seals. The inboard bearing moved upward 0.023”, while outboard went down 0.017”. The motor moved upward 0.002” on the outboard bearing, 0.013” inboard. This required the motor to be set nearly 0.060” high on the outboard bearing, and 0.032” on the inboard bearing. Not your typical motor alignment…. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 23

Case Study #1, continued Optical Alignment, Thermal Growth & Machinery Movement Alignment Study Results – #1 BFP Horizontal Data The motor outboard bearing moved 0.005” to the right, while the inboard bearing moved right 0.013”. The pump outboard bearing moved about 0.004” right, while the inboard bearing was essentially steady. This required the motor to be offset to the left to achieve reasonable horizontal alignment. The motor was found to be bolt-bound and could not be moved to the ideal position. Notes: Suction and discharge piping enter from the top of the pump barrel. The pump is centerline mounted. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 24

Case Study #1, continued Optical Alignment, Thermal Growth & Machinery Movement Thermal Growth Results – #2 BFP Vertical Data The motor and pump demonstrated much more typical responses, although the pump was found to grow more significantly than the pump vendor had anticipated for this center-hung design. Final vertical motor alignment required removing 0.010” from all feet, which was performed at a later date. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 25

Case Study #1, continued Optical Alignment, Thermal Growth & Machinery Movement Alignment Study Results – #2 BFP Horizontal Data Unlike #1 BFP motor, this motor moved 0.006” to the left at both bearings. The pump showed a similar twisting motion as #1 BFP, but was more pronounced. This resulted in the motor needing to be offset 0.025” at the outboard bearing, and 0.016” at the inboard bearing. Once again, not your typical alignment….. Notes: Suction and discharge piping enter from the top of the pump barrel. The pump is centerline mounted. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 26

Case Study #1, continued Optical Alignment, Thermal Growth & Machinery Movement Conclusions The two otherwise “identical” boiler feed pumps, mounted only a few feet away from each other, required significantly different cold alignment offsets to produce acceptable alignment while operating at full-flow conditions. The required offsets, especially on #1 BFP, were far outside the values recommended by both the OEM and a pump repair specialist that was on site. Following realignment to the required position, and re-adjustment of the inboard bearing seal, the #1 BFP ran without alignment-related seal problems for over 18 months. #2 BFP was later realigned and has run very well. Notes: Suction and discharge piping enter from the top of the pump barrel. The pump is centerline mounted. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 27

Case Study #2 – Large Turbine-Generator
Optical Alignment, Thermal Growth & Machinery Movement Rigid couplings & short bearings spans need attention…. Machinery Configuration Turbine: 3,600 rpm Coupling: Rigid, rabetted-fit Generator: 75 MW Customer Problem: OEM set alignment during outage. High vibration and seal rubbing experienced during startup. Orbital & shaft centerline data analysis confirmed the measured misalignment. Notes: Be sure to explain H-A, H-B are for horizontal measurements; V-A, etc. are for vertical measurements. The same benchmarks can be used for both types of readings. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 28

Case Study #2, continued Optical Alignment, Thermal Growth & Machinery Movement HP to LP Turbine – As-Left OEM Alignment Coupling faces were left “open” 0.013” (13 mils) on the bottom, placing bearing #1 at 0.104” above the coupling, and bearing #2 about 0.010” high to the coupling. No significant offsets were used. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 29

Case Study #2, continued Optical Alignment, Thermal Growth & Machinery Movement LP Turbine to Generator – As-Left OEM Alignment Coupling faces were left approximately fair, with no significant offsets. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 30

Case Study #2, continued Optical Alignment, Thermal Growth & Machinery Movement Alignemnt Study Results We found 0.065” growth at bearing #1 (turbine front standard), with 0.050” at bearing 2. Bearings #3, 4 and 5 showed 0.020”, 0.019” and 0.015”, respectively. The cold coupling and combined hot alignment data are shown below. Note high bearing metal temperatures of 190° at bearings #1 & #4. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 31

Case Study #2, continued Optical Alignment, Thermal Growth & Machinery Movement Conclusions To normalize bearing loadings, we recommended the following shim changes (shown in green below): Bearing #1: no change Bearing #2: ” Bearing #3: ” Bearing #4: no change Bearing #5: ” Customer has yet to make any changes, and has since had fluid-induced instability at bearings 2 and 3, and mechanical problems at bearing 1. Notes: Customer has yet to make any changes, and has since had © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 32

Case Study #3 – Process Compressor Train
Optical Alignment, Thermal Growth & Machinery Movement High speed requires high precision…. Machinery Configuration Turbine: MHI; 4,831 rpm; 27,000 HP Couplings: all disc-pack LP Cmpr: Elliott 60M81; 4,831 rpm Gearbox: MAAG HP Cmpr: Elliott 29M6I; 11,047 rpm Customer Problem: High 1X-filtered vibration on LP compressor since water induction event. Misalignment & unbalance suspected. Notes: Be sure to explain H-A, H-B are for horizontal measurements; V-A, etc. are for vertical measurements. The same benchmarks can be used for both types of readings. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 33

Case Study #3, continued Optical Alignment, Thermal Growth & Machinery Movement Alignment Study Results Using prior cold shaft-alignment data and measured thermal growth data, the results below were obtained. While this graph is ‘busy’, we can see the hot offsets present at each side of each coupling. Shaft Deviation values were calculated for each coupling, and are shown on the Misalignment Tolerance Graph on the next slide. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 34

Case Study #3, continued Optical Alignment, Thermal Growth & Machinery Movement Results SRB Notes: Shaft deviation (mils / inch) calculated for each side of each coupling. The highest (worst) value for each coupling is plotted on the Misalignment Tolerance Graph. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 35

Case Study #3, continued Optical Alignment, Thermal Growth & Machinery Movement Conclusions Significant misalignment was found on the LP Compressor to Gearbox coupling, and was suspected to be a major contributor to LP Compressor vibration. The large horizontal offsets caused a 1X ‘crank-effect’ across the disc-pack style coupling. This contributed to the residual mass unbalance in the rotor, and caused unacceptably high vibration. Significant misalignment was also found on the HP Compressor to Gearbox coupling. Alignment changes were recommended to the customer, but the site has yet to shut down the process to allow corrections to me made. SRB Notes: Shaft deviation (mils / inch) calculated for each side of each coupling. The highest (worst) value for each coupling is plotted on the Misalignment Tolerance Graph. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 36

Case Study #4 – Generator & Exciter
Optical Alignment, Thermal Growth & Machinery Movement High stiffness coupling sensitive to offsets…. Machinery Configuration Generator: 850MW; 1,800 rpm Coupling: large disc-pack Exciter: 2-bearing; 1,800 rpm Customer Problem: High 1X-filtered vibration on exciter bearings prompted alignment & vibration study. Notes: Be sure to explain H-A, H-B are for horizontal measurements; V-A, etc. are for vertical measurements. The same benchmarks can be used for both types of readings. © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 37

Case Study #4, continued Optical Alignment, Thermal Growth & Machinery Movement Alignment Study Results Using a 0.007” parallel offset alignment, as supplied by the customer, and adding the thermal growth for the generator and exciter bearings, we have the hot alignment shown below. It was interesting to note nearly equal vertical thermal growth on the generator and exciter bearings. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 38

Case Study #4, continued Optical Alignment, Thermal Growth & Machinery Movement Shaft Centerline Data Proximity probes were used to gather vibration and shaft centerline data from the generator and exciter bearings. During startup from zero to 1,800 rpm, the shaft at bearing 8 (exciter-end of generator) moved upward 0.010” and to the right 0.003”. Bearing 9 (drive-end of exciter) moved up 0.003” toward bearing center. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 39

Case Study #4, continued Optical Alignment, Thermal Growth & Machinery Movement Shaft Centerline Data Data from bearing 10 showed the shaft moving up only about ”, and slightly to the left, about ”. Note: For counter-clockwise rotation (viewed from generator to exciter), we normally expect the shaft to rise and move to the right due to the lubricating oil forming a wedge in the lower-left quadrant of the bearing beneath the shaft. As the shaft rotates, this wedge creates direct and quadrature stiffness components that lift and push the shaft toward the lower-right bearing quadrant. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 40

Case Study #4, continued Optical Alignment, Thermal Growth & Machinery Movement Alignment Study Results When we add the shaft centerline movement within the bearings (due to oil wedge effects) to the hot alignment, we arrive at the dynamic vertical alignment conditions shown below. The rotors appeared to be well aligned, with only a 0.003” offset at the coupling in the vertical direction. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 41

Case Study #4, continued Optical Alignment, Thermal Growth & Machinery Movement Conclusions The rotors appeared to be well aligned, with only a 0.003” offset at the coupling in the vertical direction. Horizontally, we did not have thermal data, but cold alignment and dynamic offsets also yielded less than 0.003” total offset. The customer indicated the large disc-pack coupling was not loosened during the last alignment check. Due to its size, it will have an impact on the exciter’s alignment readings, especially any offset readings at bearing 9. We have recommended a coupling inspection, including runout checks of all hubs, and a re-check of the cold alignment with the disc-pack bolts loosened. This will allow an accurate indication of the exciter shaft alignment. Soft-foots checks of the exciter frame will also be performed to reduce frame foot vibration. Notes: © 2007 M&B Engineered Solutions, Inc. Optical Alignment, Thermal Growth & Machinery Movement © 2007 M&B Engineered Solutions, Inc. 42

Thank You – Any Questions?
Optical Alignment, Thermal Growth & Machinery Movement Thank You – Any Questions? © 2007 M&B Engineered Solutions, Inc. 43

Optical Alignment, Thermal Growth, & Machinery Movement

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Optical Alignment, Thermal Growth, & Machinery Movement

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