Rotabolt: Tensioning a bolt with this device does not require a torque-measuring instrument. Rotate the fixture to 12:00.4. Record dimensions of removed components and take required pictures of component condition. Set the face dial indicator to zero.4. Rotate the fixtures to the 6:00 position and read the amount of sag. Have You Taken The Reliability Leader Fluid Cleanliness Pledge? A joint venture between two of the worlds largest steel companies inspired innovative approaches to maintenance reliability that incorporate the tools, technology and techniques of today. This mark represents the point where the rim dial indicator contacts the shaft or coupling hub and is labeled: DIR. Mounting hardware Mounting hardware consists of the brackets, posts, connectors, and other hardware used to attach a dial indicator to a piece of machinery. Note: Assure all piping/tubing is isolated from flush/quench ports. In most cases, however, this error is not enough to bother eliminatingit is easier just to make a few more corrective moves, reducing the error each time. If any leaks are observed, consult Seal Vendor immediately. Always completely check and clean the associated seal flush system when replacing seals. Span the coupling with a rod.3. Figure 3.3 Positive readings when the plunger moves into the case, negative when the plunger moves out. Rust, atmospheric corrosion, or corrosion from leaking gaskets can cause damage to these fits, making it impossible to ensure a stuffing box that is concentric with the shaft. 4. This unit can be purchased as a complete assembly as shown in (Figure 2.21) or as individual components. Factors that influence how much sag exists include: Dial indicators can easily be attached to brackets and, because brackets are adjustable, they can easily be mounted on shafts or coupling hubs of varying size. After plotting the two points, to determine the movable shaft position perform the following steps: 1. This method is a clever one for face-mounted brackets. Instead, only measure and record the normal lift of the valve stem at the top of each power cylinder head. Determine and record the reading on both dials.9. Vertical and horizontal angularity and offset are clearly shown as are the feet position. 0000013689 00000 n
Observation of such measurements should be recorded to the nearest 1/16 in. To determine sag, perform the steps below: 1. Record the DIR and DIF dial indicator TIR values.To determine offset and angularity from the 12:00 TIRs, use the following rules: Measuring & Interpreting Horizontal Misalignment. %PDF-1.4
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To plot the offsets, perform the following steps: 2. Check Camshaft and/or Layshaft Drive Chain. The stuffing box should be concentric to the shaft axis to within a 0.005 inch total indicator reading. Install gland to seal chamber using opposite and even tightening technique. What would cause a shaft on an exhaust fan to ware on only one side? For this reason, the primary seal faces must be free of fingerprints, oil, and/or grease. Always clean and deburr the mounting surfaces when installing O or V seals. Remove shaft and Bearing bracket from casing and mark the dimension where the back of the retainer sits when assembled. It is important to note that indicator bar sag cannot be determined from a reading taken by rotating the shafts. By continuing you agree to the use of cookies. Seal Chamber face flatness should be no more than 0.005 TIR. Be sure that every seal installation uses the vendor supplied job-specific seal drawing reviewed prior to the old seal being removed and before new seal installation. If you are using the NXA or XA laser system from Fixturlaser the visuals you see on the results and live screens are an actual representation of the movable machines position. The pictures below are of the NXA Pro or Ultimate. As the plunger moves out of the case, the needle travels counter-clockwisegiving a NEGATIVE reading. The procedure for the assessment of the flatness deviation with straightedge and dial indicator (Fig. COST: The cost differential between the MagBolt and the Rotabolt appears to be, on average, $60, with the MagBolt being the most cost-effective. At turns out there was a .003 shaft deflection due to a loose fit between the bearing collar and shaft. 2. One example is the improper use of magnetic bases, which are generally designed for stationary service. Intelligent asset management, asset condition monitoring and reliability in a single conference and expo! Rotate the dial indicators to 9:00.10. Industrial maintenance as a service (#imaas) transfers the digital and/or manual management of maintenance and industrial operations from machine users to machine manufacturers (OEMs), while improving it considerably. Set both dial indicators to zero.3. (not completely around shaft). This corrects the error as shown in Figure 5-14. Measuring Angularity With Face Dial Indicators. Dial indicators are measuring devices designed expressly to measure relative position. To measure angularity using dial indicators, a fixture bracket is attached to one shaft and the dial is set-up to contact the face of the other coupling hub. Rotate the dial indicators to 9:00 and zero them.2. These seals have larger radial clearances between the shaft and wider seal faces to prevent over-wipe of the seal faces during standard operation. Standard graph paper is about 10 inches across. There are ever-increasing opportunities to create new and sustainable value in asset-intensive organizations through enhanced use of technology. Figure 3.9 Measuring angularity, position #1. 0000000896 00000 n
This movement is transmitted to a pinion, through a series of gears, and on to a hand or pointer that sweeps the dial of the indicator. Install the Mating Ring using a Press and a piece of cardboard between press and mating ring. 0000001941 00000 n
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Be careful NOT to make mathematical errors when subtracting signed numbers.3. If the movable shaft is below the horizontal stationary shaft reference line, the shaft is too low. New mixer seal technology is available making tolerances up to 0.250 inch F.I.M. When shaft angularity readings are obtained in this manner, the amount of angularity equals the total indicator reading (TIR) divided by the indicator circle diameter. Always find tools, measuring instruments, and materials prior to start of job. To determine sag, install the dial indicators on the alignment fixture in the same orientation and relative position as in the actual alignment procedure with the fixture resting on a level surface as shown in Figure 5-13. Move the front feet of the movable machine as you watch the rim indicator move to zero.5. Using this specific methodology, sag error applies equally to the top and bottom readings. Check Condition and ClearanceMaster Rod Bearings. Plastic plugs need to be installed in all flush/quench ports after isolation of piping/tubing up to the point of the piping/tubing reinstallation. Set the face dial indicator to read zero.3. Note the dial indicator reading while holding the upward force. 0000002053 00000 n
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For shaft alignment, we typically use dial indicators with 0.250 0.300 total travel. Set the dial indicator to zero. If, however, major misalignment exists, and/or the rim or shaft diameters are small, a significant error is likely to be present. The hash mark is installed at the factory during calibration when the bolt is hydraulically stretched to the desired tension. Consult the seal vendor for the proper pressure if static limit is not indicated on seal drawing. We use cookies to help provide and enhance our service and tailor content and ads. Check bearing clearance with dial indicator and jack. If there is not enough room on the shafts, it is permissible to attach brackets to the coupling hubs or any part of the coupling that is solidly attached to the shaft. Before obtaining alignment measurements, determine dial indicator bar sag of the rim dial indicator and ensure dial indicator readings are valid and repeatable. Use dial indicator and bar to measure clearance. The total travel (all the way out to all the way in) varies depending on the particular indicator model. See Section 2 for details. The dial indicator plunger must be centered for equal positive and negative travel.5. Donald M. Harrison, in The Grouting Handbook, 2013. The dial is set to zero at position #1, for example, 12:00. Use a torque wrench for critical component bolt torques and always refer to the OEM drawings for any specific torque requirement BEFORE referring to a general torque table! Eccentricity alters the hydraulic loading of the seal faces, reducing seal life and performance. Rim readings are obtained as the shafts are rotated and the dial indicator stem contacts the shaft at a 90 angle. Note the reading on the scale. It includes the three PMs: predictive, preventive and proactive maintenance. Next, mount the alignment fixture on the coupling hub with the dial indicator plunger touching the top vertical rim of the opposite coupling hub. You must divide offset TIR by 2 to determine offset. ; ^P -
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To avoid this, level the rim measurement surfaces of both posts in coordination and rotate precise 90 quadrants using an inclinometer. The positive or negative signs (+/-) for the displayed values refer to position and the value is the distance from the reference centerline at that point. William E. Forsthoffer, in Forsthoffer's Proven Guidelines for Rotating Machinery Excellence, 2022, See following Awareness information for our proven pump mechanical seal installation procedure, Set of Hexagonal Wrenches (Allen)Metric and Imperial. What Is Industrial Maintenance as a Service? When adjusting the movable machine, while in the live screen, and the foot values are increasing, move the other way! Remove spark plug or gas/air injection valve. Check the load by simply twisting the inner or outer control caps with your fingers. Rotate both shafts (if possible) to 3:00.3. As the shaft rotated, the bearing race would wobble axially on the shaft causing the wear. We had replaced bearings on this fan and with in a month the bearings had failed, and on one end of the fan shaft the shaft was wore down about an 1/8 only on one side of the shaft? A way to minimize this error is to use jigs, posts, and accessories which square the circle. Here we attach flat surfaces or posts to the curved surfaces, and level them at top and bottom dead center. Figure 3.10 Measuring angularity, position #2. Measuring Angularity With Face Dial Indicators 2. When it comes to criticality analysis, there are three key factors must be emphasized. August 1, 2022. When interpreting the graph to determine the movable shafts front and rear feet positions in the horizontal plane, view the graph the way you view the machine, that is, standing behind the movablemachine facing the stationary machine. The dial is set to zero at position #1, for example 12:00. There are two ways to eliminate these last two inclined-plane errors. Draw a horizontal line at the center of the page. Note: If sleeve O ring is installed, confirm proper material, size, and durometer, and apply a small amount of Krytox or equal lubrication and install. #-p Hq=yX:+?d-[${L(-DYN&+hq!G# ePVm:2#F(:mH)RTh0X+2^q~n')l8TbR#!Wc%xI S&;Fwx~>:nC
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8m'nhE'|M4^wP"|2^g?E#uaF}5prZ>kJqSj?%lUlv1yV3G Repeat steps 4 & 5 until both dial indicators read zero. Why do you think these two projects rank so much higher in this method than the first method? the facilitator asked the director of reliability. Make the third vertical line representing the point along the shaft length of the rear feet of the movable machine (RF).Upon completion of the steps above, the graph will look similar to the one shown below. MurrayJr., in Centrifugal Pumps (Second Edition), 1992. The T + B vs. S + S test, which is described in Murray [6], will detect inclined-plane error if this is present. It is not intended that any disassembly of the camshaft box be made to complete this preventive maintenance step. 2022 Certified Reliability Leader Workshops by Reliabilityweb.com, 2022 Certified Maintenance Manager Workshops by Reliabilityweb.com, International Maintenance Conference (IMC) 2022, Job Postings for Maintenance and Reliability Professionals, Free eBook: 11 Problems With Your RCA Process and How to Fix Them, Alignment, Vibration, Balancing and Ultrasound Training mapped to UPTIME ELEMENTS, Asset Performance Management and Reliability Software. As shim changes are made, check for and take precautions to avoid creating soft foot conditions.Making horizontal corrections. Always assure that all components within the flush system have been cleaned or replaced when changing out a mechanical seal as dirty components (cooler, seal pot, plugged orifice, etc.) Also observe the following rules: To correct vertical misalignment, follow the steps below: 1. If removed components can be refurbished, immediately initiate procedures for this action. Always match mark components and note location relative to fixed machine surface and note standoffs and rotor running position reference prior to removal of any components. at the seal chamber possible. If making live vertical corrections, for machines with adjustable chocks, the coupling and foot values are the position of the moveable machine and the arrows show whether to remove or add shims. Rotate the dial indicators to 3:00.6. If the inner cap turns, the bolt has lost its minimum designed preload. Connect with leading maintenance professionals, reliability leaders and asset managers from the world's best-run companies who are driving digital reinvention. Conventional seals designed for mixer canisters with integral bearing support can only tolerate small runouts, less than 0.062 inch. HWnEZv/\[- "x$BqbG3b[D9"(N3UOJxmDHF]N?tppzwJ|;*vz3 %(ziKR)/v^dJ*A0V'4 5].?saG%0G*t5g3l1$z3%5NaC$oe"aJ{EQFfdp8'o2I]!YhC4jP@k`vhvOoT7d&-+}5\pJ Determine and record the reading on both dials.11. The number of set up options are too numerous for this discussion. 0000001287 00000 n
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SZKMY8se< Record the DIF and DIR dial indicator TIR values.To determine offset and angularity from the 3:00 TIRs,use the following rules: Calculating the front and rear feet positions, Positive values mean the foot is high, shims must be removed. Negative values mean the foot is low, shims must be added.Rim-Face Calculation Precautions, 1. To measure offset using dial indicators, a fixture bracket is attached to one shaft and the dial is setup to contact the other shaft. When we align equipment, we are aligning the rotational centerlines of the shafts. Plot the second offset point using the shaft slope (Face TIR / A dimension). Obtain graph paper with 10 divisions between bold lines.2. The shift in forces during rotation can cause movement of the magnetic base and erroneous readings. This article addresses the best maintenance strategy for assets by using ACA techniques. A dial indicator should be attached to the shaft and the shaft will be rotated to cover a complete sweep of the seal chamber face. It uses a finger-operated indicator; however, this device can have one or several hash marks permanently stamped into the head of the bolt. trailer
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Ensure the rim and face dial indicator TIRs are properly determined from the dials prior to performing calculations.2. If seal must be installed over damaged shaft surface, assure that seal alignment is correct. 0000013813 00000 n
Figure 5-14 shows this conventional method that, except for the sag compensator device, is almost universally employed. 0000012580 00000 n
What is Machine Misalignment Costing You? 5. Jig posts, although useful, can also cause problems if not handled properly. Dial indicators and mounting hardware are the equipment needed to take alignment readings. Each in. The plunger is fully extended out of the case if no pressure is applied to it. Make a second vertical line representing the point along the shaft length of the front feet of the movable machine (FF).7. If it is not kept to a minimum, it is often not repeatable and, therefore, introduces different amounts of error. Set the rim dial indicator to the positive sag value.3. R Keith Mobley, in Plant Engineer's Handbook, 2001. With the plunger set to approximately mid-position, the face dial is set to read zero. 0000005795 00000 n
In addition, certain oils can set-up like adhesives and pull material out of the carbon primary ring faces after start-up, resulting in premature seal failures. 1. The dial indicator plunger must be centered for equal positive and negative travel.Fixture Mounting Precautions. Also, if the jig post has a flat surface, it eliminates curvature error that can sometimes reduce measurement accuracy on small diameters. The bending action occurs as a result of gravity and cannot be totally eliminated in almost all cases of alignment. Inspect Power Cylinders with Boroscope. Ensure you divide the Rim Dial TIR by 2 to obtain an offset value. Stiffness of the fixture hardware materials Plot the offset from the rim dial indicator on line DIR. Always confirm shaft or shaft sleeve surface finish, clean seal chamber, and confirm proper spring fits and spring compression when installing a new component seal. Mixer shaft orbiting, i.e., operating with excessive runout. Perform operations inside parenthesis first.4. This article highlights the hidden trap of performance management systems. One is by using precisely machined jig posts that give the desired result automatically when mounted on shafts. Tighten bolts in an equal and opposite manner (same tightness first at 3Oclock, then 9Oclock, etc.) As long as the amount of bar sag is known and is consistent, it can be compensated for during the alignment process. The primary parts of a dial indicator are the face or dial, the case, and the plunger. Improper installation of mating ring into the gland resulting in excessive leakage due to improper face contact. Regardless of the specific hardware being used, the following precautions should be observed. The other offset point is derived from the face dial indicator (DIF) reading andthe A dimension. We have a stationary machine and a moveable machine. Figure 3.7 Measuring offset, position #2. Confirm that shaft or shaft sleeve surface finish, where secondary O ring or Teflon wedge will ride, is maximum of 32rms, using a comparator. If gross misalignment is not present, and if coupling and/or shaft diameters are large, which is usually the case, accuracy will often be adequate. Brackets eliminate the need to disassemble flexible couplings when checking alignments during predictive maintenance checks or when doing an actual alignment. Check Condition and Clearance of Power Piston Articulated Pin Bushings. The plunger is a spring loaded part that can be depressed into the case causing the dial to move clockwise. Turn the graph paper so that the long side is horizontal.3. A dial indicator is an instrument with either jeweled or plain bearings, precisely finished gears, pinions, and other precision parts designed to produce accurate measurements. Rotate the dials to 12:00 and ensure both dials return to their original setting. Apply very lightly to O ring to assure that lubricant does not enter the seal faces. Figure 3.5 Determining bar sag, reading at 6 oclock. 0000023818 00000 n
The point that contacts the shaft is attached to a spindle and rack. Also note any observations in writing for RCFA assistance. Just releasedMRO Best Practices Special Report - a $399 value! Specific geometry of the hardware arrangement. We correct for sag in the following manner: In Practical Machinery Management for Process Plants, 1998. 3. 6. Move the rear feet of the movable machine as you watch the face indicator move to zero.6. 0000024191 00000 n
Figure 13-53. Read instructions in OEM (Original Equipment Manufactures) manual for removal of components before attempted removal and have the job-specific manuals and drawings out at the jobsite during work. Position the indicator plunger(s) at the 12:00 position and set the dial(s) to zero. Always install nuts after thorough cleaning, deburring, and prelubrication. This will allow for partial replacement and can be used with broken existing anchor bolts. Clean and deburr the shaft area and seal chamber area as required using a solvent that will be compatible with the process fluid. From this zero reference point, two rules apply: For readings where the dial is normally zeroed at 12:00 and rotated to 6:00, set the dial to the positive value of sag at the 12:00 position. Referring to the illustration below, notice that the offset between the two shafts is 0.020 (0.508 mm), but the TIR is 0.040 (1.016 mm). When correcting the vertical position in the shim screen, pay attention to the add or remove shims direction of the arrows. Primary seal face flatness will have been confirmed by the seal manufacturer and should be within 12 helium light bands. When the packing is removed, orbiting of the shaft in the stuffing box area may be as much as 0.150 inch F.I.M. Their flat measurement surfaces can introduce an error in the case of a gear or gridmember coupling turned in such away that backlash is present. 53 0 obj <>
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Visually inspect bearing for signs of deterioration. With the dial indicator set up as described above, place the indicator stem well into the bore of the stuffing box. REGISTER NOW! In Practical Machinery Management for Process Plants, 2005. This where the pictorial representation is helpful. After seal is completely installed, conduct a static pressure check. Use the horizontal line representing the stationary shaft centerline as the reference. Use. Figures 13-52 shows an example of conventional mixer seal technology. Deviations from this value are an indication of worn lobes on the camshaft, and appropriate repair steps should be initiated. Mixer seal with increased runout capabilities. Although sag may be minimized by proper bracing, sag effects should still be considered in vertical alignment. With the coupling broken, mount the fixture to the stationary shaft or coupling hub.2. 5. The sag compensator feature incorporates a weight beam scale that applies an upward force when the indicator bracket is located at the top of the machine shaft, and an equal but opposite force when the indicator bracket and shaft combination is rotated to the down position, 180 removed. Using a ruler or straightedge, draw a line through the two offset points that extends to the rear feet of the movable machine.2. Any bolt receiving these devices must be drilled and tapped in its center on the nut (top) end for positive anchoring of the device at a depth within the bolt to allow for accurate stretch measurement. 0000013355 00000 n
Ensure the two plot points are properly determined from TIRs.4. Auxiliary flat surface added to avoid curvature-induced measurement error. The same problem would be present in a jig post with a curved measurement surface, if the surface is not concentric with the shaft center. This will assure an even press fit and proper seal between O ring and mating ring. Attach the face dial indicator. Always double check the position of vertical lines drawn to represent the DIR, FF, and RF.3. Measurement is visual, using a steel scale. TIR should be no more than 0.005. In most cases the stationary machines center of rotation is the target and reference for all measurements and corrections of the movable machine. The wear on one side is typical of a machine element rotating around a stationary shaft, however his is not the case as this is the outboard One is the offset measured in the plane of the rim dial indicator (DIR). MagBolt: This device does not require a torque-measuring instrument to check its load. of the shaft at the face of the seal chamber (Figure 13-51). Span of the indicator bar(s) With a small sling and scale, lift the indicator end of the fixture so that the fixture is in the horizontal position. It could be viewed as representing the vertical position (as viewed from the side) or the horizontal position (as viewed from above). Figure 13-51. 0000005521 00000 n
This is the case regardless of the Fixturlaser tool you are using. Malcolm G. Maintenance reliability is, of course, an essential part of any successful business that wants to remain successful. * Ensure positive offsets are plotted above the horizontal reference line and negative offsets are plotted below the line.5. Many mechanical seals are installed on mixers with a bearing support in the seal canister that limits shaft deflection at the seal faces. It is desirable to have 360 degrees of rotation. In Practical Machinery Management for Process Plants, 1997. Do not attach brackets to a movable part of the coupling, such as the shroud. Both of these devices mechanically monitor the bolt elongation during tensioning like a micrometer or dial indicator. Let us assume, for example, that we observe a dial indicator reading of 0.004in. The "A" Dimension is the diameter of face indicator travel. Plot this point counting from the DIR offset point! 0000013885 00000 n
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n. Precut shims aren't always what they're marked; many shim manufacturers designate shims with the nominal thickness.4. Visually inspect bushings for signs of deterioration. Numerous attempts have been made by fixture manufacturers to minimize the amount of sag that occurs; however, none have been successful in eliminating it for all alignment situations, only in minimizing it. Note that misuse of equipment can result in costly mistakes. In other instances, especially when retrofitting packed mixers to mechanical seals, the bearing may not be present and shaft deflection or orbiting can occur in the seal chamber area to levels that will cause contact between the shaft and stationary components of the mechanical seal. Figure 3.6 Measuring offset, position #1. Figure 13-52. Positive values at the feet mean that the movable machine is high, therefore you will remove shims. The dial is then rotated 180 degrees, for example, to the 6:00 position. Long spans between coupling halves may cause the dial indicator fixture to sag measurably because of the weight of the fixture and the dial indicators. The two types of face design are balanced and continuous. 80% of Reliabilityweb.com newsletter subscribers report finding something used to improve their jobs on a regular basis. For this method to be fully effective, rotation should be performed at accurate 90 quadrants, using inclinometer or bubble-vial device. 0000004667 00000 n
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o\ Secure a large workbench at the job covered with clean white paper so tools and materials remain clean and organized. Rotate both shafts (if possible) to 12:00. When we move a machine that is mounted in a horizontal position, such as a pump and motor, we reposition the movable machine by moving in only two planes, vertical and horizontal. Assure shaft surface is clean and free of any burrs and carefully install sleeve being sure O ring is not damaged. In cases of gross misalignment where the offsets will not fit on the page, a larger scale, such as 2-3 mils per division, is sometimes required. The reason is that as the fixtures are rotated from 12:00 to 6:00 while mounted on the machine, the reading given includes a combination of sag and misalignment.