Instruction Manual. User s Guide

Transcription

1 Digital Electronic BENCHMARK GAUGES for Effective Hot Alignment of Turbomachinery Instruction Manual and User s Guide Acculign, Inc. 600 Lytton Lane Dale, Texas Phone: Fax:

2 CONTENTS Warranty Notice...Below Introduction - On-Line Monitoring of Coupling Alignment... 1 Choosing the Appropriate Method... 2 For Accessible Bearing Housings... 2 Dual Benchmark Arrangement... 3 Computer Programs... 5 Selecting Benchmark Locations... 5 Installation Photographs... 6 Installing Benchmarks... 9 Special Considerations Taking Benchmark Readings Care of Benchmark Gauges Notes WARRANTY NOTICE Important Note to Purchaser Acculign products carry a limited warranty for a period of one year from date of purchase. Warranties do not apply to products that have been damaged by accident or misuse, or as a result of service of modifications other than through Acculign, Inc. In all cases, packaging, shipping and reimportation arrangements and charges are the responsibility of, and to the account of the user. Products are sold on the basis of specifications applicable at the time of manufacture, and there is no obligation to update products once sold. Products out of warranty will be serviced on a time and material basis. Seller s and manufacturer s only obligation shall be to replace such quantity of the product proved to be defective. Neither seller nor manufacturer shall be liable for any injury, loss, or damage, direct or consequential, arising out of the use of or inability to use the product. Before using, the user shall determine the suitability of the product for his intended use and user assumes all risk and liability whatsoever in connection therewith. Due to the rapidly-changing nature of the electronics industry, no warranties or claims are made as to the length of time for which any electronic product can be obtained, serviced or repaired. The foregoing may not be altered except by an arrangement signed by the officers of seller and manufacturer.

3 INTRODUCTION - ON-LINE MONITORING OF COUPLING ALIGNMENT PROPER ALIGNMENT OF TURBOMACHINERY HAS LONG BEEN RECOGNIZED AS A PREREQUISITE TO SAFE, TROUBLE-FREE OPERATION OF SUCH EQUIPMENT. BENCHMARK GAUGES PROVIDE A SIMPLE AND RELIABLE MEANS OF OBTAINING ON-LINE DATA FOR THE PURPOSE OF MONITORING COUPLING ALIGNMENT. Benchmark gauges offer a simple, reliable, and effective means of securing hot alignment data for turbomachinery trains by accurately measuring the movement of the machines relative to the foundation itself. With the Acculign system, benchmarks are permanently affixed to the foundation and to the machines at or near each bearing location; i.e., at both ends of the equipment casing. If bearing housings are readily-accessible, benchmarks are located as in Figure 1. Where bearing housings are not readily-accessible, benchmarks may be placed as shown in Figure 2. In both cases, all benchmarks at a given location lie in a plane perpendicular to the shaft centerline. Using benchmark gauges, distances between pairs of benchmarks are measured and recorded at the time of final cold coupling alignment, as are the angles at which the measurements are taken. Benchmark gauge sets include an inclinometer for measuring these angles. When the machines are brought on line and attain normal operating temperature, the distances between benchmark pairs are once again measured and recorded. Minor changes in angles are of no significance, do angles need not be re-measured. Using PC programs that are provided with Acculign benchmark gauge sets, vertical and horizontal movements of the machines can be calculated from recorded data, as can actual running alignment of the coupling. 1

4 CHOOSING THE APPROPRIATE METHOD While the equipment to which benchmark gauges are applicable varies widely in size, design, and complexity, the general requirements for placement of benchmarks are virtually universal. Mounting details will vary with each installation, of course, and it is recognized that the user will be called upon for innovations to suit the specific situation. As discussed in the previous section, one of two general methods is normally used to secure benchmark gauge data: For Accessible Bearing Housings When bearing housings are readily accessible, a benchmark is placed on each side of the bearing housing and two associated benchmarks are placed on the foundation. Figure 3-A and 3-B below, show typical arrangements. All benchmarks at a given location should lie in a common plane perpendicular to the shaft centerline. When they are located in this manner, normal axial movements of the equipment will have no adverse effect upon benchmark gauge data. With this arrangement, machine movements are calculated using Sketch 401. See COMPUTER PROGRAMS, Page 5. 2

5 Dual Benchmark Arrangement When bearing housings are not readily accessible, as with barrel compressors or similar equipment, benchmarks may be placed as shown in Figures 4-A and 4-B, below. Dimensions A and B must be equal. Place benchmarks on the flange as close as practical to the shaft centerline. Foundation benchmarks need not be symmetrical. Dimensions A and B must be equal. Place benchmarks on the flange as close as practical to the shaft centerline. Foundation benchmarks need not be symmetrical. Use this arrangement when foundation width is limited. Again, all benchmarks at a given location should lie in a common plane perpendicular to the shaft centerline. With this arrangement, machine movements are calculated using Sketch 402. See COMPUTER Programs, Page 5. 3

6 Sketch 201 Sketch 202 Sketch 401 Sketch 402 4

7 COMPUTER PROGRAMS A PC computer program called GAGES.EXE is furnished with Acculign benchmark gauge sets. Included are three programs for evaluation of benchmark gauge data, and two programs for evaluation of coupling alignment, as follows: Sketch 201 Coupling Evaluation, Face & Rim Method Sketch 202 Coupling Evaluation, Reverse-Indicator Method Sketch 401 Benchmark Evaluation, Normal Placement of Benchmarks Sketch 402 Benchmark Evaluation, Dual Benchmarks Sketch 403 Benchmark Evaluation, Non-Ideal Placement (see text below) Background for these programs, as well as detailed instructions for their use, is included in the Instruction Manual for the Acculign Coach Alignment Computer. This instruction manual is furnished with benchmark gauge sets. Examples of worksheets for these programs are shown on the preceding page. Non-Ideal Benchmark Placement If the benchmarks deviate significantly from the desired plane and/or there is substantial axial movement of the equipment, then the effect of non-ideal placement of the benchmarks must be considered. To determine whether or not it is necessary to use the more complex Sketch 403 (see Coach instruction manual, Page 36), the user should make trial calculations as follows: 1. Calculate machine movements using Sketch Using the same data, calculate machine movements using Sketch 403. If the actual axial movement of the equipment is not known, assume a reasonable movement for this trial calculation. Compare the results. If differences in calculated machine movements are significant, then Sketch 403 should be used. If Sketch 403 must be used with a dual-benchmark configuration, calculate the movement at each side of the machine separately, then average the results to obtain machine movements at the shaft. SELECTING BENCHMARK LOCATIONS When properly installed, Acculign stainless steel benchmarks will provide the basis for accurate and repeatable hot alignment data throughout the life of the rotating equipment. The following guidelines are provided to assist the user in placing benchmarks for optimum performance of the benchmark gauge system. For most equipment, there is considerable flexibility in the specific choice of locations for benchmarks. Survey the equipment in detail to find the best locations for a particular machine; i.e., locations that will ensure accurate measurements of machine movement while offering accessibility for installation of benchmarks and for taking benchmark gauge readings. Some of the points to keep in mind when locating benchmarks are: (Continued on Page 8) 5

8 INSTALLATION PHOTOGRAPHS 6

9 7

10 SELECTING BENCHMARK LOCATIONS (CONT D) 1) Select Appropriate Angles. For optimum accuracy, select locations such that the included angle between sets of readings at each bearing housing location is between 60 and 120, as shown in Figures 3 and 4. An angle of 90 is ideal. If the included angle is very small (both benchmark gauge readings nearly vertical), vertical movement of the equipment will be determined with a high degree of accuracy. Calculated horizontal movements may be less precise. Conversely, if the included angle is large (both readings nearer horizontal), then the horizontal machine movement will be measured with very good accuracy, but the data for vertical movement may be less accurate. Also, please note the 90 limitation in Sketches 3 and 4. While one benchmark reading from each set may be vertical, the angles must never exceed 90 from the horizontal. 2) Select Permanent Locations. Select locations that are truly permanent, such as the machine casing of the lower half of a bearing housing. Avoid placing benchmarks on components that will be removed and replaced during normal maintenance, such as coupling guard flanges or bearing housing covers. Figures 5- A through 5-F, Page 9, show recommended locations for bearing housings. If benchmarks must be placed on removable parts, be sure that these parts are properly doweled in place to ensure accurate reinstallation. In this regard, cylindrical dowels are much more accurate in re-locating machine components than are tapered dowels. 3) Avoid Interference. Position benchmarks so that they do not interfere with normal maintenance and operation of the equipment. When placing benchmarks on the foundation, try not to encroach upon walkways. 4) Use the Foundation. Wherever possible, place benchmarks directly in the concrete foundation rather than on a structural steel baseplate. Concrete foundations are generally subject to less distortion (thermal and mechanical) than are baseplates. Be sure, however, that the concrete in which the benchmark is placed is integral with the foundation, and not a separate concrete walkway or pad. When benchmarks must be placed on baseplates, be sure they are located on structural members, not on steel decking, and be sure that the baseplate is properly grounded and that the foundation bolts are tight. Avoid locations that may be subject to undue thermal distortion; i.e., well away from steam lines or other high temperature piping. Do not install benchmarks atop integral lube oil sumps. 5) Consider Accessibility. Choose locations where the benchmark gauge can be installed easily, and where the digital readout is clearly visible when taking readings. In this regard, it is a good idea to have the benchmark gauge set in hand when selecting benchmark locations (See Item 4, Page 11). Photographs of benchmark installations are shown on Pages 6 and 7. 8

11 INSTALLING BENCHMARKS To ensure accuracy and repeatability of benchmark gauge measurements throughout the life of the equipment, benchmarks must be installed permanently. They cannot be removed and re-installed without adversely affecting benchmark gauge data. For applications requiring long-term benchmark integrity, use a one-piece, stainless steel, covered benchmark, Acculign Item No. 10. These covered benchmarks are installed on rotating equipment by drilling and tapping a 3/8-16 NC hole to accept the 3/8-16 stud that is furnished with the benchmark. Ideally a 1ʺ diameter spot face should be provided, but the spot face may be omitted if the surface upon which the benchmark will seat is relatively flat and smooth. For added security, an epoxy adhesive may be added to the threads and to the base of the benchmark at the time of installation. Benchmarks may be screwed to baseplates or soleplates, or they may be welded directly to the structure by removing the stud. Remove the plastic cover while welding. To install a benchmark in concrete, use the Benchmark Mount, Acculign Item No. 20. Drill a 5/8 ʺ diameter hole approximately 2 ʺ deep into the concrete and install the mount and the covered benchmark. For added security, an epoxy adhesive may be added to the benchmark mount and to the mounting threads at the time of installation. Avoid installing benchmarks with adhesives only. Benchmarks mounted with adhesives only have generally failed to remain mounted for long-term use. 9

12 It is sometimes necessary to make a bracket or extension upon which to mount a benchmark. When this is necessary, please keep the following in mind: a. Make the bracket very rigid and mount it securely. It many cases this bracket will someday be used as a step by a very large craftsman. b. Install the bracket such that it need not be removed for maintenance of the equipment. Weld the bracket in place whenever possible. SPECIAL CONSIDERATIONS Overhung Pumps. To ensure optimum accuracy of benchmark gauge data, it is important to have a reasonable separation between the two planes in which benchmarks are located. As a general rule, these places should be separated by no less than 10 inches (250mm). For small pumps of overhung design where this separation is not feasible, it may be possible to locate one benchmark plane near the coupling and the second benchmark plane near the suction flange of the pump. Benchmark gauge readings in a single plane should be avoided. While vertical and horizontal movement at the benchmark plane can be determined with a single-plane reading, angularity (twisting) that is common with overhung pumps cannot be determined in this manner. Parallel-Shaft Gears. For parallel-shaft gears, it may be difficult to install benchmarks so as to take gauge readings at all four bearing locations. As a practical alternative, it is common to take benchmark gauge readings only at the bearings adjacent to the input and output couplings of the gear. In so doing, the assumption is made that both bearings on the low speed shaft experience similar vertical and horizontal movement during operation. Similarly, it is assumed that both ends of the high speed shaft experience similar movement during operation. This is usually a very good assumption since the shafts must remain parallel if the gear is to perform properly. In addition to the benchmark gauge readings at bearing locations, it is also very useful to make direct vertical benchmark gauge readings from the foundation (or baseplate) to the horizontal gear case flange at the four corners of the gearcase. Determining vertical movement at the four corners of the gearcase provides valuable data on gearcase warpage which can be extremely detrimental to gear operation. Disk or Diaphragm-Type Couplings. When using disk or diaphragm-type couplings, it is often advantageous to determine differential axial movement of coupled machines to ensure the couplings are not over-extended. Benchmark gauges can be useful in this regard. By placing a benchmark on the coupling-end of each coupled machine, a simple benchmark gauge reading can determine the differential axial movement of the casings of the two machines. See Photograph No. 13, Page 7. 10

13 TAKING BENCHMARK READINGS To ensure the maximum effectiveness of benchmark gauge readings, it is essential that the reference set of benchmark gauge readings, including angles, be taken simultaneously with alignment readings at the coupling. This is normally done at the time of final alignment of the coupling. Angles are measured with the inclinometer (Photograph 6, Page 6). When such simultaneous readings are taken and recorded, there will exist a specific, known relationship between benchmark gauge readings on a given equipment train and the alignment of the couplings on that train. Having established this relationship, then coupling alignment can be determined at any time merely by securing new benchmark gauge readings and calculating coupling alignment by using the PC programs provide with the Acculign system (See COMPUTER PROGRAMS, Page 5). Instructions for taking benchmark gauge readings are outlined on an instruction sheet affixed to the benchmark gauge data case. These instructions are repeated below: 1. To calibrate the gauge, install it in the standard and press the On/Zero button. The display will show zeroes, and will indicate in or mm (inches or millimeters) depending upon the mode of operation the last time the gauge was used. If the wrong mode is displayed, press the in/mm button to change the display. 2. Remove the gauge from the standard and take benchmark gauge readings as desired. When the gauge is removed from the standing, it will read a positive number corresponding to the available free travel of the gauge. This will be on the order of 5.2 inches (140mm) for the standard tool set, or 3.2 inches (85mm) for the short range tool set. Note that a negative reading will be displayed when the gauge is fully compressed. This denotes over-travel in the compressed direction which is required to install the gauge over benchmarks. 3. It is a good idea to re-calibrate the gauge periodically while taking readings, and to re-check the calibration after the last readings are taken. 4. If a reading must be taken in a location where the display is difficult to read, insert the gauge between benchmarks and press the On/Zero button to zero the gauge. Remove the gauge and any extension that is being used. Place the gauge in the standard and note the reading, which will normally be a negative (minus number). To determine the distance between benchmarks, change the sign of the reading (minus to plus), and add this reading to the value of any extension that is being used. As an example, if the extension marked 35 inches plus dial reading is being used, and the gauge reading is when it is placed in the standard, the distance between benchmarks is 35 inches plus inches, or inches. Re-zero the gauge in the standard prior to taking any additional readings. This technique is also useful if reading are being taken on a machine that is vibrating sufficiently to make the last one or two digits in the display difficult to read. 5. If the gauge is moved very rapidly, an error message E os will appear indicating overspeed. If this happens, re-calibrate the gauge in the standard. (Continued on Page 12) 11

14 TAKING BENCHMARK READINGS (CONT D) Continued from Page Protect the gauge from moisture. If the electronics get wet, the display may go blank or give erratic readings. If this happens, wipe any moisture from the gauge and place it in a warm, dry place for a few hours. Generally, the gauge will work properly again when it is dry. 7. A B in the display indicates a low battery. Other signs of low battery are a dim display or erratic readings. The battery may be changed merely by removing the cover on the face of the gauge. The battery is a very common 1.5 volt silver-oxide or alkaline cell of the type used in cameras and calculators. The international designation is SR44. Replacement battery numbers from various vendors are shown on the spare battery vial. 8. Turn the gauge off before returning it to the case. CARE OF BENCHMARK GAUGES Acculign benchmark gauges are rugged tools designed for field use. With reasonable care, and with minimal maintenance, they will provide many years of dependable service. The following are general recommendations for care of the tools: 1. Store the tools in the carrying case. 2. Keep the tools clean. The primary construction material of benchmark gauges is stainless steel, and they are easily cleaned by wiping the tools with lint-free cloth using common solvents or soap and water. Pay particular attention to the spherical seats; they must be clean to ensure accurate readings. 3. Never use oil, WD-40, or other lubricants on the benchmark gauge. A very light film of oil is permissible on the sliding digital scale. Otherwise, the gauge is designed to work without lubrication. 4. Protect the electronics from moisture. If the electronic readout gets wet it may not function, or it may give erratic readings. Should this happen, wipe off any excess moisture and place the gauge in a warm, dry place for a few hours. The readout should again work properly when it dries out. 5. If the tool is to be stored for long periods of time, remove the battery as would be done with any electronic device. 6. Replace the battery at the first sign that it is getting low; i.e., illumination of the letter B in the display, or when the display becomes dim or erratic. 7. Keep a fresh battery on hand. Batteries generally have an operating life in excess of one year, and a shelf life of two years or more. 8. Inspect the tools as they are being used. If the tool becomes damaged, have it repaired. 12

15 NOTES Thank you for using Acculign products 13

16 Acculign, Inc. 600 Lytton Lane Dale, Texas Phone: Fax: