Chapter 2 Installation INTRODUCTION Proper installation of the machinery will contribute to long trouble-free operating life with minimum maintenance. To aid in making a proper installation, this chapter describes a detailed procedure that has proven successful for installing numerous turbines and the associated equipment. The following chapter contains the installation methods recommended by KEPL-Elliott Company. Other procedures do exist which can provide a satisfactory installation; however, prior to using any of these alternate procedures, it is recommended that the purchaser carefully investigate both the procedure and the ability of workers to produce a permanent and satisfactory installation. KEPL-Elliott Service Representatives are experienced in installation procedures and can assist in providing a good installation. The installation procedures contained in this chapter are as specific as possible but cannot possibly cover all variations in field conditions. Therefore, the KEPL- Elliott Service Representative may sometimes deviate slightly from the published procedures. This is done to give a better installation by using procedures to fit specific field and service conditions. Regardless of the procedure used, first class materials and quality workmanship should be employed. The procedure recommended by KEPL- Elliott involves the following items: 1. 2. 3. 4. 5. 6. 7. Foundation Chock Blocks Grouting Setting the equipment on foundation Shaft alignment Coupling Installation Piping Recommendations
Included in this chapter is a detailed procedure for making "cold alignment" as well as methods for making machine "hot alignment" checks.
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Chapter 2 Installation While many aspects of an installation are the responsibility of the purchaser or his engineer, some suggestions are offered which may contribute to suitable installation. One such example is whether to install the machine outdoors under only a roof, or in a completely enclosed building. While this class of equipment can generally be installed outdoors, local conditions may suggest alternate arrangements. Freezing or low ambient temperatures around machinery can create difficulties during start-ups and shutdowns; for example, lubricating oil must be warm before starting equipment. Water and steam equipment must be drained completely or heated during shutdown. Alternately, in tropical areas, direct sun on one side of the foundation might cause expansions which, when coupled with other factors in the system, could create unacceptable alignment. In addition to operating considerations, maintenance and equipment inspections will be required - sometimes scheduled and occasionally unscheduled. Regardless of which, weather conditions may not always cooperate. Rain, snow, wind and low or high temperatures generally extend maintenance and inspection when workers are exposed directly to these elements. In addition, quality of workmanship may be lowered to a point where work accomplished is futile. For inspection and maintenance, a permanent overhead crane or hoist is recommended. Casing top halves and rotors have close clearances which must be protected, therefore, moves must be slow and positive. This is seldom achievable with crawler or wheelmounted cranes. Installation of the machinery may be on either steel soleplates or a self-supporting fabricated steel baseplate. The functional purpose of these intermediate supports is to provide a permanent mounting plate for the machine feet that can be shimmed. When the foundation support is not continuous or is mounted directly on columns, a self-supporting fabricated steel baseplate must be designed that will minimize deflections between contact supports. Soleplates usually provide support for only one machine or smaller equipment strings. In most cases, a baseplate is made to support larger equipment strings. Some baseplates are also designed to contain or support lubrication and seal system piping and instrumentation in addition to the machinery. Baseplates with the lubrication system built in may require less space and have lower installation cost, but are generally more difficult to maintain. Installations of a self-supporting baseplate on a reinforced concrete foundation should follow the guidelines presented with only the sections indicated on the outline drawing left unsupported. When the installation of a self-supporting baseplate is on structural steel or columns, care must be exercised to insure that the mounting surfaces are machined level (from end to end and side to side there should be less that 0°, 6’ slope) and flat (each pad must be flat within .003” (.076mm)). Full contact between the mounting surfaces is required without the use of step shimming. With this installation arrangement, grouting is not used to fill in gaps, but other procedures presented in this chapter should be followed. See Figure 2-1.
Chapter 2 Installation
BASEPLATE PAD SHIMS STRUCTURE PAD PLANT SUPPORTING STRUCTURE
FIGURE 2-1 TYPICAL BASEPLATE MOUNTING ARRANGEMENT ON STRUCTURAL STEEL FOUNDATION The principle function of the foundation is to provide a permanently rigid, non-warping support for the machinery. In meeting these requirements, the foundation should: • hold machines in proper alignment under all operating conditions • support the machine's weight and load, and distribute it uniformly and evenly to the soil or main support structure • maintain established equipment locations • minimize transmission of vibration to or from the machines. While the responsibility for a successful foundation rests with the purchaser, the following suggestions are offered for assistance and consideration: 1. The outline drawing provides equipment mounting surface areas, anchor bolt locations, main piping connections, and other information necessary in designing a foundation. A foundation of reinforced concrete should be of ample size and proportion for adequate support of the machinery, as well as piping forces such as inlet and discharge piping. Provision should be made in the foundation design for accessibility to all parts of the machine or its auxiliaries during operation, inspection and maintenance. 2-3
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Chapter 2 Installation 4. The foundation should rest entirely on natural rock or entirely on solid earth. A foundation resting partly on one or partly on another may warp due to settling of part of the foundation support. Distortion may also occur due to unequal pressures created by differences in ground water level. Foundations supported on pilings should have a rigid continuous cap over the pilings on which the foundation rests. Temperature surrounding the foundation should be uniform. Temperature differences between the top slab and mat, for instance, can create substantial bending stresses in columns. Care must be taken to reduce thermal distortion from radiation or uneven heating and cooling. Direct sunlight on outdoor tropical installations is to be avoided. Steam lines passing close to the foundation should also be avoided; but when unavoidable, the lines should be insulated and the foundation shielded. Foundation should be isolated from all other structures and arranged so that outside vibrations are not transmitted to it. Where foundations must be supported by floor beams, a vibration dampening material should be interposed between the beams and the foundation. Design of foundation structure should avoid resonant frequencies of operating speed, 40% to 50% of operating speed, rotor critical speeds, and two times operating speeds. It is recommended that concrete foundations be allowed to cure for approximately 28 days before loading. This will allow for development of strength and reduction in shrinkage rate. Curing procedure should be in accordance with American Concrete Institute recommendations.
10. Recommended size of foundation anchor bolts and projection above foundation is shown on the outline drawing. Suggested installation of the anchor bolt is as shown in Figure 2-2. Use of a pipe sleeve around anchor bolt allows for some shifting of the anchor bolt if found necessary during installation of equipment. It allows for increased stretch length of anchor bolts. 11. When establishing the top elevation for the foundation, allow approximately 0.5 inch (12 mm) for removal of top crust of concrete by chipping. Reinforcing rods, ties, or steel members should be sufficiently below the surface to permit chipping away of approximately 1.00 inch (25 mm) of concrete without making contact. A minimum space of 1.00 inch (25 mm) should be provided between foundation and chock block to provide adequate room for insertion of grout. The maximum distance between the foundation and soleplate or baseplate should not exceed 4.00 inches (100 mm). Figure 2-3 is a cross-sectional view showing the location of a soleplate with chock blocks, chock block grout and final grout. Figure 2-4 is similar but shows the location of a baseplate with chock blocks, chock block grout and final grout.
Chapter 2 Installation
CHIPPED HALF OF ROUGH FOUNDATION
0.50 IN. (12 mm) + 1.5 D 4.00 IN. (100 mm) MAX. BETWEEN BOTTOM OF BASEPLATE AND FOUNDATION 1.00 IN. (25 mm) MIN. BETWEEN CHOCK BLOCK AND TOP OF ROUGH FOUNDATION
FINAL GROUT (DO NOT POUR UNTIL FINAL ALIGNMENT ADJUSTMENTS HAVE BEEN MADE)
9 x D MIN. 2 xD MIN. D 2 x D RADIUS
CHOCK BLOCK PIPE SLEEVE
5 xD MIN.
7 x D MIN. ANCHOR BOLT
REINFORCING ROD (PLACE SUFFICIENTLY BELOW FOUNDATION SURFACE TO PERMIT NECESSARY CHIPPING)
FIGURE 2-2 SUGGESTED ANCHOR BOLT ARRANGEMENT
EQUIPMENT SOLEPLATE SHIMS CHOCK BLOCK HOLD DOWN SCREW FOUNDATION BOLT PIPE SLEEVE
ROUGH FOUNDATION SURFACE
CHOCK BLOCK GROUT
FIGURE 2-3 TYPICAL SOLEPLATE MOUNTING ARRANGEMENT
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Chapter 2 Installation Foundation Preparation When the foundation is constructed of reinforced concrete, it is not practical to pour the concrete block with the necessary precision to permit setting the machinery directly onto the block. Therefore, the soleplate or baseplate is set with a void between it and the foundation. After the soleplate or baseplate is positioned, machinery placed and cold alignment check made, the soleplate or baseplate is cemented or grouted to the foundation. This procedure essentially creates one continuous support for the machinery.
BASEPLATE PAD SHIMS PIPE SLEEVE
CHOCK BLOCK ROUGH FOUNDATION SURFACE
HOLD DOWN SCREW
CHOCK BLOCK GROUT
FIGURE 2-4 TYPICAL BASEPLATE MOUNTING ARRANGEMENT In order to obtain good bonding surfaces for the grout, all defective concrete, laitance, dirt, oil, wax, grease and loose material must be removed from the mating surfaces. This can best be accomplished by chipping, bush hammering or by other means until sound, clean surfaces are obtained. Removal of approximately 0.5 inch (12 mm) of the top concrete surface should provide a strong, laitance-free surface for bonding and anchoring of the grout.
Chapter 2 Installation CHOCK BLOCKS In this manual, the term "chock block" is used to describe steel or grout blocks that serve to level and support the soleplate or baseplate prior to full grouting. The size of a steel chock block may vary, but the two sizes shown in Figure 2-5 will generally satisfy most all conditions. When steel chock blocks are furnished by Elliott Company, the blocks will conform to the information provided in Figure 2-5 or when desired this figure can be used to make chock blocks. To provide for ease of installation and leveling, four jackscrews are furnished in the chock block. A screw anchor in the center of the block is used to anchor the chock block securely until grouting in of the blocks. Chock Block 1. 2. 3. Material carbon steel plate Machine both top and bottom flat Break all corners and chamfer all holes
1.0 in. 25 mm
0.5 in. 13 mm
8.00 in. OR 12.00 in. 203 mm OR 305 mm
4.00 in. 101 mm
0.75 in. 19 mm
4 - SET SCREWS 1/2" - 13 x 1-1/2" LONG OVAL POINT OR EQUIVALENT MACHINE SCREW 1/4" - 20 x 3" LONG FLAT HEAD OR EQUIVALENT SCREW ANCHOR SHIELD TO MATCH MACHINE SCREW
FIGURE 2-5 TYPICAL CHOCK BLOCK
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Chapter 2 Installation Epoxy grout chock blocks can also be used in place of steel chock blocks. When using epoxy grout chock blocks, small forms should be positioned at each anchor bolt just as suggested for steel chock blocks. The top surface of each form should be level and at essentially the same elevation as all other chock block forms. Forms should be anchored, coated with wax and sealed around the bottom. When pouring grout, forms should be completely filled. This will minimize need for shimming between chock and baseplate or soleplate. Use of chock blocks allows the installation workmen to easily make a change in elevation at a soleplate or baseplate support pad. The chock blocks also distribute the machinery weight and hold down nut force so that deflections of the soleplate or baseplate due to these forces are minimized. With chock blocks, the soleplate or baseplate can be easily shifted horizontally without disturbing established elevations. For maximum effectiveness, two chock blocks should be positioned at each foundation anchor bolt as shown in Figure 2-6. Machines mounted on baseplates generally have the foundation anchor bolts spread out and close to only one edge; therefore, placement of chock blocks can usually be accomplished as shown in Figure 2-6. For machines mounted on soleplates, the number of foundation anchor bolts increases while available surface area decreases, therefore making effective placement of chock blocks more difficult.
ANCHOR BOLT CHOCK BLOCK
APPROXIMATELY 4.00" (100 mm)
BASEPLATE OR SOLEPLATE
FIGURE 2-6 PREFERRED LOCATION OF CHOCK BLOCKS
Chapter 2 Installation Figure 2-7 shows a preferred arrangement when space is available, while Figure 2-8 illustrates an alternate arrangement that may be used. The arrangement used should provide maximum support and minimize deflection or warping to the soleplate or baseplate during installation work.
36.00 in. (900 mm)
12.00 in (300 mm)
FIGURE 2-7 PREFERRED LOCATION OF CHOCK BLOCKS
20.00 in (500 mm)
9.00 in (320 mm)
TWO CHOCK BLOCKS
FIGURE 2-8 ALTERNATE LOCATION OF CHOCK BLOCKS Figure 2-9 illustrates a typical arrangement with chock blocks positioned on either side of the foundation anchor bolt. As described earlier, the foundation surface must be prepared by chipping or other means prior to setting the chock blocks. The chock block surfaces, where a bond with the grout is desired, must also be cleaned prior to setting. Surfaces must be free of oil, dirt and oxidation. If the chock blocks have been coated with a catalyzed epoxy primer, the surface coating should not be removed but surfaces should be cleaned with solvent to remove any oil or dirt prior to setting.
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Chapter 2 Installation
Foundation anchor bolt Temporary plug Seal Chock block Leveling screws Chock block grout Form Sea l Chipped foundation surface Obtain this dimension from the certified outline drawing
1.00 in (25mm) min. Screw anchor Hold down screw
FIGURE 2-9 TYPICAL CHOCK BLOCK ARRANGEMENT The chock block surfaces should be sandblasted if coated with rust or some other surface coating. Sandblasting is best, but a disk grinder or other mechanical method can be used. If chock blocks will be immediately grouted after setting, no further surface treatment is required. A clean, sandblasted surface will provide a good bonding surface. If grouting in of the chock blocks will be delayed after cleaning, the cleaned surfaces should be coated with an epoxy primer or surface coating recommended by grout supplier. To set a chock block, determine the chock block anchor screw locations on the foundation and drill 0.5-inch (12 mm) diameter by 1.00-inch (25 mm) deep holes (if screw anchor shield is other than that shown, appropriate drilling should be used) in the concrete. Position the chock block and engage the screw anchor as shown in Figure 2-9. Level the individual blocks using the four setscrews provided. All blocks must be level and approximately at the same elevation. It is desirable to maintain all chock block elevations within a few thousandths of an inch or a few hundredths of a millimeter. This makes final installation and shimming of the equipment much easier. On installations where overall length of the equipment is short, elevation of the chock blocks can best be set by use of a straight edge and precision level. On installations where the overall length of the equipment is large, use of a precision tilting level may be advantageous. Regardless of the method used, shimming should be used between the chock blocks and soleplate or baseplate to correct any elevation variations required. NOTE Before making a check of chock block level and elevation, be sure anchor screw is tight and all four leveling screws are making contact with the foundation.
Chapter 2 Installation GROUTING The procedure to be followed for grouting in of chock blocks, soleplates or baseplates is the same except for quantity of grout placed. Elliott recommends that the grout used be a good quality epoxy grout system from a reliable manufacturer of heavy machinery grouts. Epoxy grouts consist of an epoxy resin, hardener and graded silica aggregate. The resin and hardener serve as the adhesive while the aggregate serves as a filler to reduce cost, improve thermal expansion compatibility and absorb heat released by curing. With proper application, an epoxy grout should provide a permanent, reliable installation. Use of sandcement grout or sand-cement grout with various additives may also provide an adequate installation, however both are generally lower in strength, have more tendencies to shrink unevenly and are generally more susceptible to chemical attack and deterioration by oils. The prime purpose of grouting is to: • Fill all voids between the foundation and the soleplate or baseplate. • Provide a permanent bond between the foundation and the soleplate or baseplate. • To assist the foundation anchor bolts in preventing lateral movement. • Provide a solid, level base to which the machine can be anchored by the foundation anchor bolts to prevent vertical movement. • Make the soleplate or baseplate more or less an integral part of the concrete foundation. As anchor bolts are designed for hold down purposes, it is desirable to provide for some stretching of the anchor bolt between the bottom of the sleeve and the bottom of the nut. Therefore, it is recommended that the sleeve be filled with a pliable material such as silicone rubber, prior to final grouting. Use of epoxy grouts requires some installation procedures that differ from those used for sand-cement grouts. The procedure that follows provides a general guide for use with epoxy grout; but for more specific details, consult the grout supplier's bulletins or labels. This is particularly important in regard to safety precautions.
-WARNINGMOST EPOXY GROUT IS FLAMMABLE, TOXIC, POISONOUS, AND CORROSIVE. THEREFORE, MATERIAL SHOULD BE KEPT AWAY FROM OPEN FLAME, HIGH HEAT SOURCES OR SPARKS. IT SHOULD BE MIXED IN A WELL-VENTILATED AREA. WORKMAN SHOULD WEAR EYE PROTECTION AT ALL TIMES DURING MIXING OF GROUT AND HARDENER AND ALSO WHEN APPLYING MIXED GROUT. GLOVES AND PROTECTIVE CLOTHING SHOULD BE WORN AT ALL TIMES. When grouting in baseplates, thermal expansion rates between sand-cement grout and steel or an aggregate filled epoxy grout and steel generally can become significant. Therefore expansion joints should be installed when stretches greater than approximately three feet are encountered. After the foundation has been dressed, the surface of the expansion joint should be sealed with silicone rubber. 2-11
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Chapter 2 Installation Timing and proper mixing are the secrets to successful grouting. Before mixing the components together, everything else should be ready - surfaces cleaned and dry, forms completed and sealed, pushing tools, rags, cleaning solvents available and adequate manpower. Because of epoxy grout's higher compressive and tensile strengths and its readiness to bond to metals, the top of the grout should be brought up along the side of the soleplate or baseplate to give some protection against lateral movement. Grout forms should be built of materials of adequate strength and should be securely anchored and shored to withstand the pressure of the grout under working conditions. For epoxy grout, the forms must be waxed to keep them from becoming bonded to the grout. For chock block grouting, the anchor bolt sleeve should be sealed and the form height sufficient to provide a grout height approximately half way up the chock block. Because the epoxy grout will flow through even the smallest holes, the forms must be fit together as tightly as possible. Putty can be used as caulking for small cracks or holes. To permit easy cleanup, wax or cover all surfaces where grout may splash. For outdoor installation, the foundation should be protected from rain since it is important that the foundation be clean and dry at the time of grouting. Normal grouting temperature should be between 40° and 90°F (4° and 32°C). Due to the accelerated rate of curing at high temperatures, shade the foundation from summer sunlight for at least 24 hours before and 48 hours after grouting. In the hot summer weather, place the grout during the afternoon so the initial cure will occur during the cooler evening hours. In cold weather, the grout materials should be stored in a warm place. Low temperatures make the grout stiff and hard to handle. For best results, ingredients should have an actual temperature of 70°F (21°C) or higher. Refer to instructions for the particular grout mix being used for allowable working time at various ambient temperatures. Flow grade epoxy grouts can generally be handled with the same methods and tools that are used with flow grade sand-cement grouts. Mixing can be done in small mortar mixers. Use of a purchased grout with all the ingredients accurately measured into convenient batches reduces the chance of error. The actual placing of the material can be accomplished by several means. Some contractors prefer to force the materials into place while others through years of experience, prefer to place the materials by other methods. The material is very viscous; however, it will flow and seek its own level given time and an ambient temperature within a given range. Generally, it is best to start at one end of the baseplate and work toward the other end, forcing the air out to eliminate voids as the material moves along. Plywood strips, sheet metal strips, wires and rods can be used to flow the grout completely under the soleplate or baseplate. NOTE Check the forms frequently for leaks. Leaks do not selfseal. If not stopped, leaks will cause voids. Forms should be left in place until the grout is hard enough throughout that it cannot flow. This usually occurs overnight but can be longer in cold weather.
Chapter 2 Installation SETTING THE EQUIPMENT ON FOUNDATION Once the chock block grout has cured sufficiently to withstand static load, installation of the equipment on the foundation may proceed. If the soleplates or baseplates have been coated with a catalyzed primer, the surface coating should not be removed but only the oil and dirt removed with solvent. If the surfaces that will come in contact with the grout are coated with some other material or rust, the surfaces should be sandblasted. While sandblasting is best, a disk grinder or some other mechanical method may be used. The cleaned surface should be coated with epoxy primer or surface coating recommended by the grout supplier. Prior to placing the soleplate or baseplate on the chock blocks, clean chock block contact surfaces and install approximately 0.125 inch (3.0 mm) thick shim pack having an assortment of shim thicknesses on each chock block. Shim pack should be full size, clean, smooth and rust free. This will provide a means of lowering any portion of the machine or baseplate that requires adjustment during leveling. Set the baseplate or soleplates on the shimmed chock blocks and tighten down all the foundation bolts. Check for level and make necessary adjustments by adding or removing shims. Normally, it is best to start at the middle and work towards the ends. All soleplate or baseplate leveling should be done using the machined support foot surfaces. Before mounting the equipment on the soleplates or baseplate, place a 0.125 inch (3.0 mm) thick stainless steel shim pack having an assortment of shim thicknesses on each machine support. A stainless steel shim pack is generally preferred. Full size shims are preferred when setting machinery or when making elevation changes during alignment. NOTE Shims and contact surfaces should be kept smooth, free of burrs and clean to prevent erroneous alignment readings. Check that coupling hubs have been mounted on their respective shaft ends before setting machinery on soleplate or baseplate. If not, refer to coupling installation procedure in this chapter and the coupling manufacturer's literature. After machinery has been placed on soleplates or baseplate, install and tighten hold down bolts. Check for a "soft foot" by loosening each hold down bolt in turn while measuring with a dial indicator movement between machine foot and soleplate or baseplate. If movement on loosening a nut exceeds approximately 0.002 inch (0.05 mm) at any foot, shim changes to eliminate the "soft foot" should be made before proceeding. With soleplates or baseplate set and leveled, machinery mounted and rough aligned, remove all temporary shipping braces.
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Chapter 2 Installation NOTE The journal bearings on the turbine have been fitted with plastic inserts for protection during shipment. These plastic inserts must be removed before the rotor is turned. If the machine is to be reshipped, the plastic inserts must be reinstalled for transit to final jobsite. Then clean the bearings and bearing housings. All clearances should then be checked. Refer to clearance table and drawings. Thoroughly oil all bearings and reassemble bearing housings. Refer to appropriate sections in Chapter 4. The machinery is now ready to be "cold aligned". The "cold alignment" method to use is dependent on the distance between the coupling hubs. For greatest accuracy, the method suggested should be used whenever possible. Initial cold alignment should be obtained prior to grouting in soleplates or baseplate. In order to provide maximum flexibility and minimum confusion, the cold alignment should be completed with all piping disconnected from the machinery. Axial coupling separation indicated on outline drawing must be maintained during cold alignment. COUPLING INSTALLATION A flexible coupling is used between the turbine and the driven equipment. This type of coupling can be manufactured for use with either straight or tapered shaft ends. Individual preferences or certain operating conditions may dictate using different types of couplings. Therefore, it is advisable to refer to the manufacturer's instructions for specific details pertaining to the coupling. Installing A Straight Bore Coupling 1. 2. 3. Clean and de-burr the coupling hub and shaft end. Place the coupling sleeve (if applicable) on the equipment shaft with the bolting flange positioned toward the shaft end. Check the key fit in the coupling hub and the shaft keyways. The key must have a side clearance of .001 inch to .003 inch (0.03 mm to 0.07 mm) between the key and coupling keyway. The fit between the key and shaft keyway must be .000 inch to .002-inch (0.0 mm to 0.05 mm) interference. The key must be fitted to provide .005 inch to .013-inch (0.13 mm to 0.33 mm) top clearance in the coupling keyway. After the key has been fitted to provide the proper clearances, insert it in the shaft keyway. Apply a light coat of suitable anti-galling lubricant on the mounting surface of the shaft. Heat the coupling hub in oil or in an oven to approximately 300°F (150°C). The coupling should not be heated with an open flame or be allowed to exceed 600°F (315°C).
4. 5. 6.
Chapter 2 Installation
-WARNINGHEAT-RESISTANT GLOVES SHOULD BE WORN WHEN HANDLING THE HEATED COUPLING.
BOLTING FLANGE SLEEVE KEYWAY LOCKNUT THREADED SHAFT END
TAPERED BORE BOLTING FLANGE
SLEEVE STRAIGHT BORE
FIGURE 2-10 FLEXIBLE COUPLINGS/TAPERED AND STRAIGHT BORE 7. Place the coupling hub on the shaft and position it so that the hub face is flush with the shaft end. CAUTION Do not drive the coupling on or off the shaft with a hammer. The force of the hammer will result in internal equipment damage. Installing a Tapered Bore Coupling 1. 2. 3. 4. Clean and de-burr the coupling hub and shaft end. Apply a light coating of Prussian blue to the rotor shaft. Place the coupling hub on the shaft. Remove the coupling and check the contact with the shaft. 2-15
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Chapter 2 Installation CAUTION Hand lapping the coupling hub on the rotor shaft may form a ridge that will affect the coupling contact when pulled up. Correct the contact by lightly stoning any ridges, burrs or high spots. 5. Check the key fit in the coupling hub and the shaft keyways. The key must have a side clearance of .001 inch to .003 inch (0.03 mm to 0.07 mm) between the key and coupling keyway. The fit between the key and shaft keyway must be .000 inch to .002 inch (0.0 mm to 0.05 mm) interference. The key must be fitted to provide .005 inch to .013 inch (0.13 mm to 0.33 mm) top clearance in the coupling keyway. After the key has been fitted to provide the proper clearances and the coupling contact is determined to be satisfactory, insert the key in the shaft keyway. Place the coupling sleeve (if applicable) on the shaft. toward the shaft end. Fit the coupling hub on the shaft (at room temperature). Take a reference dimension from the hub to a fixed part on the machine case or a shaft shoulder. Make certain the shaft is seated against either of the thrust bearings. Position the bolting flange
6. 7. 8. 9.
10. Put a small amount of thread lubricant on the drive nut. 11. Tighten the shaft locknut to obtain an interference fit between the coupling and shaft. See the Turbine Outline drawing in Chapter 10 for specifications on coupling pull up. 12. Recheck referenced dimension (step 9) and record for future use. 13. Lock drive nut. CAUTION Do not drive the coupling on or off the shaft with a hammer. The force of the hammer will result in internal equipment damage.
SHAFT ALIGNMENT The turbine and the driven equipment are normally connected by flexible couplings. Flexible couplings are used because changes in temperature and loadings during normal operation, start-up or shutdown can cause one shaft end to move relative to its companion shaft end. For high-speed, high-performance applications such as between compressors and turbines, the coupling is usually the gear, disk or diafram type.
Chapter 2 Installation All flexible couplings have limits within operation without failure or undue wear. Even when operating within the design limits, these couplings generate some resistance to flexing. The force usually increases as the misalignment increases, thereby increasing or decreasing bearing load fluctuations as the shaft rotates. Furthermore, operating with collinear shafts at normal operating conditions minimizes tooth-sliding velocity or diafram flexure while providing the maximum reserve for movement in any direction should it be required. Experience indicates that excessive vibration of compressors and their drivers is often caused by improper shaft alignment. Frequently, high or unusual bearing and seal wear can be traced to improper shaft alignment. In extreme cases, poor alignment can precipitate a coupling, bearing or shaft failure. For smooth operation and long trouble-free runs, good shaft alignment procedures are essential and cannot be over-emphasized. An understanding of good shaft alignment techniques must begin with a few basic definitions. "Cold or ambient alignment" is the procedure that involves positioning the frames or casings of compressors and other rotating machines while at standstill and ambient conditions. The "cold shaft alignment" is normally accomplished using dial indicators, feeler gauges, micrometers or a combination of these instruments. This positioning should allow for thermal growth and material deflections that will occur between ambient conditions and stabilized operating temperatures. The incremental movement used to establish the cold shaft alignment may be actual measurements made during start-up or shutdown, growths estimated by the machinery manufacturer or estimates made by the installation man. To calculate thermal expansion or contraction, multiply original length (generally distance from machine shaft centerline to top of baseplate or soleplate) times expansion coefficient (0.0000067 for steel) times temperature change in degrees Fahrenheit. (Expansion coefficient is 0.000012 for steel and temperature change in degrees Celsius.) ∆ L (change in length) = L (length) x 0.0000067 x ∆ T (change in temp. °F) ∆ L (change in length) = L (length) x 0.000012 x ∆ T (change in temp. °C) NOTE: ∆ L and L in same units. Normally, the vertical movement is minimized by use of a bolted joint where the support foot attaches to the casing. Therefore, the average temperature of the support foot may be considerably lower than the average of adjacent casing temperature to foot temperature. A good "hot shaft alignment" will either verify or suggest alternate growth figures to use. "Hot shaft alignment" also known as operating shaft alignment or service alignment is a procedure for monitoring the change in shaft alignment from cold or ambient conditions to normal operating conditions. Knowing the "cold shaft alignment" and measuring the change, provides a method for determining if the shaft alignment becomes collinear at normal operating conditions. This method is indirect, but if properly done, provides the most reliable and acceptable method available.
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FIGURE 2-11 TYPES OF SHAFT MISALIGNMENT A. Collinear alignment - In Figure 2-11 part A; the two machine shaft ends are considered to be "collinear aligned" when the two shaft ends rotate about the same straight line (no misalignment). All machinery shafts have some deflection; therefore, this reference is limited to the center of rotation of one shaft end relative to the opposite shaft end. Each coupling must be analyzed individually. B. Angular or Face displacement - In Figure 2-11 part B; indicates the amount of angular misalignment at a shaft end. Normally, angular displacement is measured in mils of offset per inch (in mm of offset per meter) of coupling diameter or axial separation. C. Parallel offset - In Figure 2-11 part C; indicates the amount of parallel misalignment between the centerlines of two adjacent shaft ends. Figure 2-11 part C, shows two shafts with only parallel offset. "Axial separation". When the coupling connecting two shaft ends is a gear type, an axial separation of plus or minus .0625 inch (1.60 mm) tolerance is usually acceptable. When the coupling connecting the two shaft ends is a disk or diafram type, an axial separation as shown in Figure 2-11 of less than plus or minus .015 inch (0.40 mm) tolerance is usually required. Check coupling drawing and coupling instructions for precise limits.
Chapter 2 Installation When aligning disk or diafram type couplings, the dimension information shown on the coupling drawings must be adhered too. Measurements should be taken with the equipment in normal thrust position (turbine rotor toward exhaust). Usually, the critical dimension is a coupling flange face dimension as shown in Figure 2-13. For further information on axial separation, refer to coupling vendor drawing and installation procedure.
FIGURE 2-12 AXIAL SEPARATION
COUPLING FLANGE FACE TO FLANGE FACE
FIGURE 2-13 AXIAL SEPARATION - DIAFRAM COUPLING There are two similar procedures available for measuring parallel offset and angular displacement. The most accurate measurements are obtained when one of the following recommended methods is used. The "Rim and Face Method" is the preferred procedure when the distance between the two adjacent shaft ends is less than one-half the coupling diameter (this assumes face readings are taken near outside diameter). This procedure is also known as the "Hub and Face Method" or "Two Indicator Method." The "Reverse Indicator Method" is the preferred procedure when the distance between the adjacent shaft ends is greater than one-half the coupling diameter.
BYR PE 100q.ch02.06/04/2007
Chapter 2 Installation Shaft Alignment Map Instructions Preparation and use of a "Shaft alignment map" for each installation is recommended. A typical shaft alignment map is shown in Figure 2-14. Use of a shaft alignment map provides a convenient form on which to record indicator readings and calculate equipment moves. Maintaining this information for comparison during maintenance inspections or for reference, should problems develop, can provide valuable diagnostic information. A blank form for your use is provided in Figure 2-17. In addition to providing machine identification information, date and shaft alignment method used, the shaft alignment map provides a plan (top) and vertical (side) elevation of the machine shafts, complete with all the important reference points identified. The horizontal or abscissa coordinate should be scaled using some convenient scale such as 1.00 or 2.00 inches per division (25 or 50 millimeters per division). All support feet and coupling faces should be located. When more than two machines are involved, a larger map or graph may be advantageous. The vertical or ordinate coordinate should be an expanded scale such as 1 mil (0.02 millimeters) per division in order to clearly identify misalignment. Mark North compass direction in plan view and corresponding compass directions in indicator reading circles so no confusion develops during measurements. When making shaft alignment corrections, it is usually advantageous to hold one machine in a fixed position and align other machine or machines to the fixed machine. Some guidelines to determine the best machine to hold stationary are as follows. 1. 2. 3. If the equipment consists of turbine driven compressor, it is generally preferred to level turbine and move compressor into desired cold alignment. If a gear is present, level and square the gear to the foundation or baseplate and move the other machinery into alignment with the gear. If the equipment string consists of three or more pieces of equipment, level the machine nearest the center, square it to the foundation or baseplate, and move the other machinery into alignment with the selected machine.
The solid, dark, heavy lines on the shaft alignment map represent the desired hot shaft alignment; i.e., collinear alignment. Plot historical or calculated thermal expansion or contraction change for each support location on shaft alignment map. Connect points plotted for each machine with a dashed line. Use dashed line for desired "cold alignment setting". Read off differences between the two dashed lines in vertical plane and record desired readings in circles so marked. Plan or horizontal alignment usually remains unchanged from ambient (cold) of bottom reading. If system has a gear, the gear case is usually doweled or keyed under the pinion and allowed to expand toward bull gear shaft thus requiring alignment allowances in plan view at bull gear or low speed shaft end. NOTE (For All Rim Measurements) Actual measurement is 1/2 TIR (Total Indicator Reading); therefore, value of measurement shown on indicator reading circle should be twice the distance indicated on plot. Offset value is plus (+) if projected centerline of machine that indicator is attached to is above coupling mark of the machine that indicator is riding on. 2-20
SHAFT ALIGNMENT MAP
USER ABC Company MP 153 SERVICE Propane Refrigeration LUBE ALIGNMENT METHOD Grease EQUIP. NO. AMBIENT TEMP. C508xxx / C5037xx 60 F ALIGNMENT BAR SAG DATE NAME Negligible MILS/MM 10 / 95
COUPLING TYPE NOTES:
1) Show North in Plan view of sketch. 2) Mark compass direction in circles. 3) If offset value is plus, projected center line of machine that the indicator was attached to will be above the coupling mark of the opposite machine. 4) If offset value is minus, projected center line of machine that the indicator was attached to will be below the coupling mark of the opposite machine. LEFT 0 COMP -12.5 W TO E TURB -25 0 COMP -10 W TO E -4 TURB -14 +7 -12.5 +10 RIGHT LEFT 0 TURB W TO E COMP +20 0 TURB W TO E COMP +16 +9 ACTUAL COLD READING +10 DESIRED COLD READING -14 0 C/T ACT RIGHT
Vo = Bot - Top = 2
Ho = Right - Left = +3 2
STEAM END FOOT PLAN
DESIRED OPERATING LINE
MOVE 6 MIL WEST
MOVE 22 MIL WEST cL cL COUPLING
DESIRED OPERATING LINE
MOVE 3 MIL UP
MOVE 17 MIL UP
14" PICK A
PER DIVISION SUGGEST 1" OR 2" PER DIVISION
FIGURE 2-14 SHAFT ALIGNMENT MAP EX
Chapter 2 Installation
Sometimes the work descriptions such as used on an alignment map can be confusing. Figure 2-15 is a pictorial view of Note 3 on alignment map. It reads: "If offset value is plus, projected centerline of machine that the indicator was attached to will be above the coupling mark of the opposite machine."
FIGURE 2-15 PICTORIAL OF NOTE 3 ON ALIGNMENT MAP Figure 2-16 is a pictorial view of Note 4 on alignment map. It reads: "If offset value is minus, projected centerline of machine that the indicator was attached to will be below the coupling mark of the opposite machine."
FIGURE 2-16 PICTORIAL OF NOTE 4 ON ALIGNMENT MAP
SHAFT ALIGNMENT MAP
USER COUPLING TYPE NOTES: 1) Show North in Plan view of sketch. 2) Mark compass direction in circles. 3) If offset value is plus, projected center line of machine that the indicator was attached to will be above the coupling mark of the opposite machine. 4) If offset value is minus, projected center line of machine that the indicator was attached to will be below the coupling mark of the opposite machine. TO TO LEFT RIGHT LEFT RIGHT SERVICE LUBE ALIGNMENT METHOD EQUIP. NO. AMBIENT TEMP. ALIGNMENT BAR SAG DATE NAME MILS/MM
Bot - Top 2 Right - Left 2
PLAN FIGURE 2-17
DESIRED OPERATING LINE
PICK A CONVENIENT SCALE
SUGGEST 1" OR 2" PER DIVISION
Chapter 2 Installation Rim and Face Method of Alignment 1. 2. 3. 4. Use Rim and Face Method when distance between the two adjacent shaft ends is less than one-half the coupling diameter. Lubricate bearings before rotating shafts. Mark both coupling hubs at four locations 90° apart so that their position is evident at all times during alignment work. All piping strain must be removed from machine. For initial alignment work during installation, all piping should be left unconnected from machinery. After cold alignment has been secured, arrange dial indicators between shaft ends, or between foundation and machine case such that any movement of machine can be detected. Connect one flange at a time and observe indicator readings continuously. Should movement exceed 2 mils (0.05 mm), piping strain is considered excessive. Reason for strain should be investigated and condition corrected before proceeding with alignment. Shift rotors to running position and determine that coupling spacer distance is as specified on coupling drawing. Mount dial indicator so indicator button rides near center of rotation. Rotate shaft against which button rests to measure axial wobble. If unable to maintain axial wobble to less than 0.001 inch (.025 mm) on either shaft, use of two face indicators 180° apart or multiple measurements is recommended. NOTE Axial shaft movement during face reading measurements can cause false readings. Two dial indicators mounted 180° apart should be used when axial float cannot be easily controlled. When using this setup, set dial indicators at 0° and 180° position and zero indicators. Dial indicator at 0° should be tagged prime dial indicator. At each interval, subtract second dial indicator's reading from prime dial indicator reading. Divide this result by two and record result in prime's location. Be sure to retain proper plus or minus signs. 7. Measure angular misalignment with inside micrometer, feeler gauges or dial indicator such as shown in Figure 2-18. This is best accomplished by marking measurement point at 0° and recording readings or change in readings between 0° point and points at 90°, 180°, 270° and 360°. On return to 0° position, indicator should return to zero or repeat measurement. Take several sets of readings, to be sure no mistake has been made or something has moved that shouldn't have. When taking measurements, rotate both shafts equal amounts to cancel out eccentricity and surface imperfections.
Chapter 2 Installation
DIAL INDICATOR WITH HOLE ATTACHMENT
FEELERS GUAGE BLOCK OR BAR STOCK 180
FIGURE 2-18 MEASURING ANGULAR MISALIGNMENT 8. Readings observed in step 7, above should be recorded on alignment map. As face readings provide the slope of shaft on which dial indicator is mounted relative to coupling face of the opposite machine (See Figure 2-19), use an indicator recording circle for an axial location equal to the "face reading measurement diameter" away from the hub on which the indicator button is riding.
DISTANCE EQUAL TO MEASUREMENT DIAMETER
FIGURE 2-19 ANGULAR DISPLACEMENT 9. To measure Parallel Offset, attach the dial indicator to bracket mounted on machine that will be moved. Set the indicator button to contact periphery of opposite coupling hub at top approximately 0.25 inch (6 mm) from edge (as shown in Figure 2-20). Set the indicator to zero at top, rotate both shafts together and record dial readings on alignment map for 90°, 180°, 270°. On return to top position, the indicator should return to zero. Repeat this procedure several times to be sure no mistake has been made or something moved. These four readings will be TIR (Total Indicator Readings), and actual parallel offset is one-half of indicator (TIR) readings.
FIGURE 2-20 MEASURING PARALLEL OFFSET 10. Readings observed in Step 9 should be recorded on alignment map in indicator recording circle corresponding to same axial location as dial indicator measuring location (fixed machines coupling). 11. Vertical offset (Vo) and horizontal offset (Ho) for projected centerline of machine to be moved at fixed machine's coupling face can be determined by using alignment map Note 3 or 4. 12. Slope of machine's shaft to be moved relative to fixed machine is determined by (a) drawing a line thorough point determined in Step 11 and parallel to fixed machine's centerline, (b) applying alignment map Note 3 of 4 to face readings at the axial location previously determined in Step 8 above. 13. In each view, draw a straight line through points located in Step 11 and 12 with line extended to intersect both supports of machine to be moved. Read off distance between line just completed and desired cold shaft position (dashed line) at each support for component to be moved. This measurement represents movement necessary to obtain correct cold alignment. 14. Make adjustments indicated in Step 13. 15. Repeat Steps 7 through 14 to verify adjustments made in Step 14 correct. 16. Unless otherwise noted, a final hot alignment should provide for an angular displacement between machine coupling hub centerline and coupling spacer centerline of approximately 0.25 mil per inch (0.25 mm per m) at the coupling gear teeth or flex elements. This angular displacement is not a limit, but a suggested alignment goal. Refer to coupling literature for more information on maximum allowable misalignment. 2-26
Chapter 2 Installation Reverse Indicator Method of Shaft Alignment 1. Use the reverse indicator method of shaft alignment when distance between two adjacent shaft ends is greater than one half the coupling diameter. Note For alignment purposes, the effective distance between shaft ends can be increased by spanning the shaft end to obtain a dial indicator location inboard of actual shaft ends. Key factor is to spread two indicators as far apart as practical with negligible bracket sag. (As spread increases, so does possibilities for bracket sag.) The reverse indicator method of shaft alignment eliminates the need for taking face readings. 2. The reverse indicator method involves taking readings from one shaft to the rim surface on the hub of the adjoining shaft and vice versa as shown in Figure 2-21.
FIGURE 2-21 REVERSE INDICATOR READINGS 3. 4. Lubricate bearings before rotating shaft. Mark both the coupling hubs at four locations 90° apart so that their position can easily be seen at all times during the alignment work.
Chapter 2 Installation 5. All piping strain must be removed from machine. For initial alignment work during installation, all piping should be left unconnected from machinery. After cold alignment has been secured, arrange dial indicators between shaft ends or between foundation and machine case such that any movement of machine can be detected. Connect one flange at a time and observe indicator readings continuously. Should movement exceed 2 mils (0.05 mm), piping strain is considered excessive. Reason for strain should be investigated and condition corrected before proceeding with alignment. When spanning the coupling gap with an indicator rig or bracket, zero sag is impractical to achieve; therefore, the actual amount of sag should be determined and recorded on the alignment map. The bracket should be sturdily constructed to minimize shifting and sag during use. NOTE For purposes of this explanation, the fixed machine is called shaft "A". The shaft of machine to be aligned to shaft "A" will be called shaft "B". Therefore, shaft "B" belongs to machine that will be moved. 7. 8. Attach the indicator bracket to shaft "A". Attach the dial indicator to the bracket so that the button will rest on the outer rim of coupling hub "B". The indicator button should contact in about 0.25 inch (6 mm) from the hub face. Position dial indicator at top dead center, in line with 0° marking on coupling "B" and zero indicator.
10. Rotate both shafts together and record dial readings on alignment map at 90°, 180° and 270° positions. On return to top position, the indicator should return to zero. Repeat this step several times to be sure no mistake has been made or something moved. 11. The accuracy of the readings may be verified by algebraically adding the side readings and comparing this sum to bottom reading. The readings should be equal to or within 1 mil (.25 mm). 12. Remove the bracket from shaft "A" and install on shaft "B". Using the same procedure obtain indicator readings from shaft "B" to the rim of coupling hub "A". 13. Using the two equations shown on the suggested shaft alignment map, calculate the vertical offset (Vo) and the horizontal or plan view offset (Ho). Plot these results in the proper view and in the axial location where indicator readings were taken. Note 3 or 4 on the alignment map can assist in determining the shaft location above or below other shaft. When making this determination, it is sometimes helpful to locate centerline of shaft end "B" first that is shaft end of machine to be moved, and then the projected centerline of shaft end "B" at shaft end "A". In this explanation shaft end "A" is fixed and therefore shaft "B" must be located relative to shaft "A".
Chapter 2 Installation NOTE Correct the bottom reading for sag in the bracket by algebraically adding to bottom indicator reading. No correction is needed on the side readings since it is negative on both sides and will cancel out. 14. In each view draw a straight line through points located in Step 13, extending the line to intersect both supports of machine "B". Read off distance between line just completed and desired cold shaft position (dashed line) at each support for machine "B". This measurement represents movement necessary to obtain correct cold alignment. 15. Make adjustments indicated in Step 14. 16. Repeat Steps 7 through 14 to verify adjustments made in Step 15 were correct. 17. Unless otherwise noted, a final hot alignment should provide for an angular displacement between machine coupling hub centerlines and coupling spacer centerline of approximately 0.25 mil per inch 0.25 mm/m) at the coupling gear teeth or flex elements. This angular displacement is not a limit but a suggested alignment goal. Refer to coupling literature for more information on maximum allowable misalignment. After cold alignment has been made, the soleplates or baseplates must then be grouted; refer to previous section titled "Grouting". After final grouting is completed, cold alignment should be checked and adjusted if necessary. Hot Alignment Check A hot alignment check should be made after the equipment string has operated with full load for several hours and stable operating temperatures have been reached. This check will indicate any final adjustments necessary to achieve collinear alignment of the turbine and driven equipment under operating conditions. The purpose of the hot alignment procedure is to measure the movement of one shaft end relative to the opposite shaft end. As the shaft rotates, it is not practical to measure the actual position of one shaft end relative to its companion with dial indicators or similar instruments, as was the case during the cold alignment procedure. Therefore, most Hot Alignment procedures make the assumption that the machine casing and bearing housing expand uniformly in a radial direction from the shaft center of rotation and maintain this relationship to the shaft center regardless of the casing temperature. This basic assumption appears to be valid as compressors and turbines are nearly symmetrical about the shaft; therefore, distortions are minimized. Using this principle, one of the following methods should be used to make a hot alignment check. The "mechanical hot alignment" method uses accurate measurements between fixed reference points on the foundation or base and the machinery bearing housings to indicate shaft movement between ambient and normal operating conditions. This method assumes that the fixed reference points do not move between cold alignment conditions and machinery operation. In general, this is a good assumption provided one side or area of the foundation is not exposed to direct sun when the other is not. Unprotected hot steam and process lines passing in close proximity to the foundation can also contribute to uncertainty in incremental movements.
Chapter 2 Installation This method eliminates the requirement for alignment brackets or bars by using permanent reference points (called benchmarks) that are affixed directly to the foundation and to the bearing housing as shown in Figure 2-22. All four reference points should lie in a plane perpendicular to the centerline of the machine shaft. Similarly mounted reference points should be established at each bearing housing in the train. Suggested benchmarks for this technique are 0.5-inch (12.7 mm) diameter precision balls. Because these benchmarks become an integral part of the installation and the accuracy of alignment records over the long term are dependent upon these references, it is recommended that the balls be made of stainless steel to prevent corrosion and mounted solidly to avoid inadvertent movement. It is also recommended that the benchmarks be protected with covers when not in use.
A' HOT BENCHMARKS
FIGURE 2-22 TYPICAL DISPLACEMENT OF BENCHMARKS ON FOUNDATION AND BEARING HOUSING NOTE Acculign, Inc markets a tool kit designed specifically for the purpose of conducting hot alignment checks by this method. Following cold alignment of the equipment string, reference dimensions A and B and angles θ and ∅ are determined at each bearing housing and recorded. Lubrication system should be operating and oil supply temperature near design to minimize effect of bearing housing growth. After the machine is brought to normal stabilized operating conditions, dimensions A' and B' are measured at each position. With these two sets of data, the vertical and horizontal movement of each bearing housing of the machines in the train can be determined relative to the foundation.
Chapter 2 Installation See Figure 2-23. Using common grid paper (5 x 5 grid is usually a convenient size), lay out reference vectors A and B at angles θ and ∅, having these vectors cross at one of the grid intersections. The intersection of these vectors represents the centerline of the machine shaft in the cold position. Now refer to the cold and hot measurements previously made (A, A', B, and B') and determine the movement of the bearing housing along vectors A and B by taking the differences between cold and hot measurements ( ∆ A and ∆ B) for each location. Lay out the movements along vectors A and B using any convenient scale, say 0.25 inch equals 0.001 inch (2 mm equals 0.01 mm), to establish points a and b.
H FINAL SHAFT POSITION a b 90 B A
VECTOR A 90 V
INITIAL SHAFT POSITION
FIGURE 2-23 GRAPHICAL DETERMINATION OF SHAFT IN HOT POSITION RELATIVE TO COLD POSITION Now draw lines through a and b perpendicular to vectors A and B. These lines represent arcs of radii A' and B' drawn from the foundation benchmarks. The intersection of these lines defines the position of the machine shaft centerline in the hot position relative to the cold position. To determine the movement in vertical and horizontal directions, it is necessary only to scale off the dimensions referred to as ∆ H and ∆ V, using the same scale as used in plotting ∆ A and ∆ B. A similar plot for the data secured at each bearing housing can be compared to the alignment map information for validity of the original estimates. Where differences exist, corrections should be made to the original estimates used on alignment map and the machinery realigned. With the permanent benchmark installed and the desired cold alignment reference dimensions recorded, this information can also be used for resetting machines quickly or for maintenance checks. Another hot alignment check is the "reverse hot alignment" method that uses the same basic principles as the reverse indicator method of shaft alignment. Rather than mounting brackets off the coupling, the brackets are mounted permanently off the bearing housing or casing.
Chapter 2 Installation Regardless of the measurement method used, several things should be kept in mind when making a setup. 1. The probes and indicating blocks should be positioned to measure both the horizontal and vertical movement at the coupling of each machine. Generally, vertical movement is the most important; therefore, placement of brackets or bars should favor making the most accurate readings in this direction (mount along horizontal centerline). The brackets or bars can either be located inside or outside the coupling guard. Brackets or bars should be constructed and protected to minimize deflections due to thermal gradients and local forces such as windage or high velocity lube oil (for brackets mounted in side coupling guard). Regardless of where brackets or bars are mounted, it must be on a thermally stable part of the machine. Regardless of where brackets or bars are mounted, it is recommended that a guard be provided to protect them.
Normally, some variations can be expected in the hot alignment data observed for various operating conditions. The central point about which most of the observations gather will normally indicate the desired operating alignment. Recording of the change in alignment data between ambient conditions and the central operating condition (desired operating alignment) on the alignment map will provide confirmation of the original data or suggest modifications to original data. The conclusion drawn from this analysis should be recorded for future use during maintenance turnarounds. Once the alignment bars have been properly installed and referenced to the cold alignment readings, the bars can also be used for aligning the machines. In addition to these methods, there are also other methods available for making a hot alignment check, such as optical alignment, non-contact proximity probes mounted on water-cooled pedestals, etc. A hot alignment check with optical equipment measures the movement of reference points (generally tooling balls mounted on the bearing housing) by use of optics. When using this method for making a hot alignment check, great care should be exercised as the line of sight between the measuring instrument and the reference point can be bent by temperature gradients or air currents. Instrument stands and their supports are also subject to vibration and distortions that can influence accuracy of data obtained. In general, it is recommended that measurements be double-checked by making measurements from both sides of machines and comparing results. Any lack of correlation should be resolved. Use of non-contact proximity probes mounted on water-cooled pedestals with the probes looking at the shaft, couplings, bearing housing or casing can also be used. When using one of these methods, great care should be exercised to design pedestals and mounting such that temperature distortions are minimized.
Chapter 2 Installation Realign as Necessary Regardless of the method used for making hot alignment check, it must be evaluated for accuracy of information measured. Temperature variations and air currents can cause significant changes in support temperatures between cold alignment conditions and operating conditions. Expansions, contractions and heat flow are therefore seldom linear. This can and does contribute to introducing errors if care is not exercised in analyzing results. NOTE Before making alignment changes based on hot alignment data, evaluate the setup to be sure data is valid and logical. When the hot alignment check confirms that the machines have been properly aligned, the machines should be doweled as indicated on the outline drawing. TURBINE PIPING RECOMMENDATIONS No part of the turbine installation is more important for successful operation than welldesigned and properly installed piping. There are two definite objectives for good piping: 1. 2. To prevent the heated piping from imposing strains on the turbine casing and, thus, affecting the alignment. To connect and drain the turbine inlet and exhaust piping so that dry steam is furnished to the turbine and that water accumulation in these lines is prevented.
A main steam isolation valve is recommended in the steam piping, preferably at a convenient accessible location in the turbine room, between the steam header and the turbine inlet, to allow working on the turbine without shutting down the boiler. The turbine casing must be protected from piping weight and piping expansion strains. The weight of piping should be carried by suitable supports. Expansion joints with limit rods or piping bends should be used adjacent to the turbine flanges. Connections between the piping flanges and turbine flanges are made without forcing the pipeline in any direction in order to make a satisfactory joint. Connections may be considered satisfactory if the connecting pipe lines, when heated to operating temperature, do not shift out of line with the turbine flanges when the bolting is withdrawn. Refer to NEMA standards for maximum forces and moments allowable. Before piping is connected to turbine, mount at least two indicators from one coupling hub to the other coupling hub-one to measure any vertical movement, the other to measure any horizontal movement. Then connect piping to turbine. If movement shown on any indicator exceeds 0.002" (0.05 mm) loosen piping and refabricate, realign or adjust anchors as required. All steam piping between the turbine and boiler or steam header must be adequately "blown down" to remove welding beads, scale, dirt, etc. During blow down, the piping should be disconnected and directed away from the turbine. Blow down should be at maximum design turbine throttle flow to obtain design steam temperature and velocity. The piping should be blown down several times, until a polished metal plate held in the stream indicates the absence of foreign material. 2-33
Chapter 2 Installation If supplied, the trip and throttle valve always contain a permanent screen to guard against the ingestion of large loose particles. In addition, many valves will also have a temporary screen installed around the permanent one. The temporary screen should be removed after approximately one month of operation and should never be left in longer than six months. Note Strainers do not take the place of a properly setup and conducted blow down. STEAM LINE BLOW DOWN (Reference SM 23; latest edition) All new steam piping between turbine and boiler or existing header must be adequately blown to remove welding beads, scale, dirt, broken backing rings, weld rod, etc. This includes all steam lines that can import steam into the turbine including but not limited to: - Main Steam - Gland Sealing Steam Proper setup and implementation of a sound blow down procedure are normally the responsibility of the installation contractor. KEPL-Elliott responsibility is normally only as a witness and to verify that placement targets are acceptable before connecting to the turbine. Since the steam lines to the turbine can not be connected for blow down, temporary blow down piping will be required. Piping must be adequately secured prior to blow down. Piping also must be rated for steam conditions at the time of the test and discharged into an area that is properly secured and marked off. In broad terms, blowing down the steam lines is a process that uses a cycle of heating and cooling to break free any loose particles. Pressure is built up in the boiler and a valve is opened to release this pressure though the steam lines. By the time the pressure is built up again in the boiler, the piping has usually cooled. This forms the heating and cooling cycle. The number of cycles will depend on the attention that was given to cleanliness during erection, the design of the plant piping system, and the design of the blow down system used. Verification of the blow down is made by installing polished targets in the temporary blow down piping. The targets are usually mild steel bar with a ground finish, however key stock material can be used. Each target can be used four times by turning the target in ninety-degree increments. The temporary blow down piping setup and size are very important. The force on a particle is proportional to the mass velocity head of the fluid; therefore the mass velocity head developed during the blowing cycle must be at least equal to that developed during full load operation. The temporary piping should not have a greater flow area than the permanent piping, so that satisfactory velocities can be maintained. It is not possible to ascertain how many steam blows will be required to properly clean the system since too many variables are involved. Experience has shown that up to fifty total blows may be required for the main steam line and ten to twenty for the secondary lines. Normally the blow down cycle will require one to three hours. The actual steam flow through the pipe should be about fifteen to twenty minutes in duration and the piping should allowed to cool for at least two hours if insulated and one hour if not insulated. 2-34
Chapter 2 Installation Polished targets are to be installed after approximately ten blows on the main steam line. At this point the targets should indicate the approximate relative condition of the system. After two successive blows with no pitting observed on the targets, the blown down can be considered completed. Retain these targets for reference. Discoloration of the targets is normal. After successful completion of the blow down procedure, the temporary piping is to be removed. Reinstall any piping removed for the blow down. Test the system for leaks and piping strain. Taking proper care to insure an effective blow down procedure has been carried out will assure a successful start-up of the turbine. TURBINE STEAM SUPPLY Steam should at all times be free from moisture. A receiver type separator with ample drains should be provided ahead of the stop valve to prevent slugs of water from entering the turbine. When a separator is not provided, a blowoff valve or continuous drain should be connected to the lowest point of the steam inlet piping. A strainer should be installed in the steam supply piping for protection against large particles of scale, welding beads, etc. A strainer does not guard against abrasive matter, boiler compound or acid or alkaline substances, which may be carried over in the steam. These substances will corrode, erode, or form deposits on the steam parts, reducing efficiency and power. It is imperative that feed water treatment and boiler operation be carefully controlled to insure a supply of clean steam at all times. TURBINE ATMOSPHERIC RELIEF VALVES An atmospheric relief valve must be installed between the turbine exhaust flange and the first exhaust line steam isolation valve (See Figure 2-24) or check valve. The purpose of this relief valve is to protect the turbine casing from excessive exhaust pressure or failure of exhaust valve. The relief valve must be of ample size to pass the maximum quantity of steam flowing through the turbine without allowing the turbine casing pressure to exceed the maximum designed pressure shown on the turbine nameplate. It is the user's responsibility to install the relief valve in the piping. Failure to install relief valve may violate local or national codes and must be approved by an officer of the company.
THE TURBINE SHOULD NOT BE OPERATED UNLESS THE ATMOSPHERIC RELIEF VALVE OR OTHER PROTECTIVE DEVICE HAS BEEN INSTALLED AHEAD OF ANY ISOLATION VALVE, AND IS IN OPERATING CONDITION. Condensing Turbines The atmospheric relief valve should be sized so that it is capable of passing all of the steam which may reach the exhaust with the pressure rising to a value not greater than 10 pounds per square inch gage. The relief valve should be installed between the turbine exhaust flange and any shutoff valve. (Usually on the condenser shell for direct connected condenser.)
Chapter 2 Installation Non-condensing Turbines A relief valve should be installed between the turbine exhaust connection and the first steam isolation valve. The valve should be designed for full relief of the maximum steam flow through the turbine with a pressure and flow rating as shown on the turbine outline drawing located in Chapter 10 of this manual. The sentinel valve located on the turbine casing cover, does not serve as a relief valve. The sentinel valve will not pass sufficient steam to relieve the turbine casing of excessive exhaust pressure. The relief valve should be set to open at the sentinel valve setting to give a visual or audible indication when the relief valve is starting to lift and be fully open with an additional 10 psig or 10% whichever is greater. If a high back pressure trip is furnished, the relief valve pressure should be raised 5 psig (.345 bar) and the high steam pressure trip should be set at the "start to open" pressure.
LOOP IN STEAM PIPE ABSORBS EXPANSION AND RELIEVES TURBINE OF STRESSES
SLOPE TOWARD HEADER
Y STEA M DR
DRAIN EXHAUST STEAM ISOLATION VALVE INLET STEAM ISOLATION VALVE ATMOSPHER I C RELIEF VALVE DRAIN
SPRING SUPPORT RELIEVES CASING OF STRESSES SPRING SUPP ORT RELIEVES CASING OF STRESSES DRAIN
Figure 2-24 Suggested Steam Piping Arrangement MISCELLANEOUS PIPING CONNECTIONS Considerable attention should be given to the installation of miscellaneous piping. Poorly planned and installed piping may obscure drain line functions and lead to error when opening or closing drain lines during operation. In addition, poorly installed piping will detract from the appearance of the installation. All drain and leakoff lines should be installed in a neat and orderly manner. They should be grouped and brought to an open collector box and, from there, piped to a common sump or sewer.
Chapter 2 Installation All valves should be conveniently grouped as close as possible to the collector box and all lines should be tagged for identification. Drain lines connected through valves must have the valves tightly closed during operation. On condensing units, these valves must not be opened unless the turbine casing is no longer under vacuum. Leakoffs, connected without valves must be clean and piped to an open drain. Refer to certified outline and connection drawings for the specific sizes of all connections and for their exact locations. The pipe size must be the same as or larger than connecting sizes. All connections are brought outside the jacket when the turbine is insulated and jacketed. NOTE All drains and leakoffs should be run as separate lines to an open collector box. NOTE All drains and leakoffs must have sufficient flexibility to allow for thermal growth of the turbine without excess strains. The following identifies the most common miscellaneous piping connections that may be furnished and explains their individual functions (Refer to figure 2-25). Refer to the certified outline and purchaser’s connection drawing to verify the connection required. 1. Casing Drain (M): Connect through a suitable valve to an open drain. Open before starting the turbine; close when water no longer emerges from the drain. Open when the turbine is shut down and the exhaust valve is closed. On condensing turbines, do not open this valve while the turbine is under vacuum. Steam Chest Drains [M4, M5, and M1 (BYRH, HH only)]: Connect through high pressure piping and suitable valves to an open drain. Open before starting the turbine to drain water from the steam chest. Close when water ceases to flow from the drain lines. Open when the turbine is shut down. On condensing turbines, do not open this valve while the turbine is under vacuum. Shaft Packing Case Leakoff (L3): Connect to an open drain without a valve. Connect to a vacuum source when applicable. Trip Valve Stem Leakoff (L4): Connect to an open drain without a valve. Governor Valve Stem Leakoff (L5): Connect to an open drain without a valve. Cooling Water Connections to Bearing Housings (N5, N6, N9 and N10): These connections are located on the side of the turbine bearing housings. See Figure 225. Connect to a cooling water supply, which does not exceed 90oF (32oC). Pipe the cooling water through a stop cock and hand valve into N5, out of N6, into N9, out of N10 through a one-foot head loop to an open drain. Adjust the stop cock to supply water at a rate of 2 gpm (7.5 l/min.) when the hand valve is fully open. See Figure 2-26 for piping arrangement of water cooled bearing housings and caps. These connections are not used on pressure lubricated turbines. NOTE Cooling water pressure must not exceed 100 psig (6.89 bar).
3. 4. 5. 6.
Chapter 2 Installation 7. Shaft Packing Case Steam Piping (T1): Furnished only when the turbine is operated condensing. Connect through a valve to a pressurized saturated steam supply. Admit steam to packing cases until a slight amount of steam leaks out of L3. A typical arrangement is shown in Figure 2-27. 8. Nozzle ring gage connection (S1): A shut-off valve and gage arrangement may be installed in this connection. The gage can be used for indicating the inlet steam pressure drop across the steam chest. Intermediate leakoff (L3-1) for BYRHH only: Connect to a 75 to 125 psig (5.1 to 8.6 bar) header. The leakoff line should have a gage located near each packing case. A valve should be used to isolate the packing cases from the header.
LEAK OFF FROM SHAFT SEALING GLANDS TRIP VALVE STEM LEAK-OFF GOVERNOR VALVE STEM LEAK-OFF TURBINE CASING DRAIN
N7 COOLING WATER TO STEAM END BEARING CAP N8 COOLING WATER FROM STEAM END BEARING CAP N9 COOLING WATER TO EXHAUST END BEARING PEDESTAL N10 COOLING WATER FROM EXHAUST END BEARING PEDESTAL N11 COOLING WATER TO EXHAUST END BEARING CAP N12 COOLING WATER FROM EXHAUST END BEARING CAP S1 NOZZLE RING GAGE CONNECTION T1 SEALING STEAM TO SHAFT PACKING CASE
HIGH PRESSURE STEAM RING DRAIN (BYRH, HH STEAM CHEST DRAIN (BELOW SEAT) STEAM CHEST DRAIN (ABOVE SEAT) COOLING WATER TO STEAM END BEARING HOUSING COOLING WATER FROM STEAM END BEARING HOUSING
ROUTE TO OPEN DRAIN NO VALVE. ROUTE TO OPEN DRAIN WITH VALVE.
Figure 2-28 Suggested Sealing Steam Piping Arrangement For Condensing Turbines VACUUM BREAKER FOR CONDENSING TURBINES It is recommended that provisions be made in the exhaust piping, or on the condenser for breaking the vacuum. The vacuum breaker may consist of a hand-operated valve to be opened when shutting down the turbine. Breaking the vacuum serves two purposes: 1. 2. It increases the deceleration rate of the rotor. It prevents the in leakage of cold air into the turbine casing along the shaft when gland sealing steam is turned off.
CONNECTING TURBINE TO CONDENSER A condenser connected directly to the turbine exhaust flange, when not suspended from the flange or spring-supported, must have an expansion joint to provide the necessary flexibility for expansion, unless otherwise approved by KEPL Company. When the condenser is spring-supported or hung from the turbine exhaust flange, no expansion joint need be used, provided the maximum condenser weight under any condition is within the allowable weight that the exhaust end is designed to support. In the latter case, the condenser load on the exhaust flange must be central. Provisions must be made in the supports for lateral expansion. All other piping connections to the condenser must be provided with suitable expansion joints. 2-40
Chapter 2 Installation To avoid air leaks and maintain the highest attainable vacuum, see that all joints are tight and that the shaft packing is receiving sufficient sealing steam. Suitable paint applied along the joints and around the bolts of the exhaust connection will assist in keeping them airtight. TURBINE INSULATION Insulating a turbine greatly reduces heat loss and sound pressure levels, isolates hot turbine parts from personnel and protects the turbine from the environment. Insulate the high-temperature areas of the turbine surface indicated on the outline drawing. For condensing turbines, these parts are the steam end casing, intermediate casing (when used), trip and throttle valve and steam chest. For non-condensing turbines, insulate the exhaust end casing also. Turbine Jacketing KEPL supplies a sheet metal, jacket-type insulation that sheathes the turbine casing. This removable jacketing, which provides access to turbine parts for servicing, separately houses the high-temperature turbine sections. Available in carbon steel or optional stainless steel, the sheet metal jacketing squares the turbine's shape for a neater appearance. Jacketing for the upper turbine casing consists of a metal shell and a layer of high-temperature fibrous insulation that is fixed to its underside. The lower turbine casing is fitted with a metal shell that is stuffed with loose insulation. Jacketing is made to each turbine's specifications and can be obtained through KEPL field service offices. NOTE KEPL- recommends jacketing for all outdoor installations to protect high-temperature turbine parts from precipitation.
FIGURE 2-29 TURBINE RECOMMENDED INSULATION METAL JACKETING