Dial Indicator Alignment Procedure.docx

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Dial Indicator Alignment Procedure

The procedure for doing reverse dial indicator alignment is not a difficult one.

There are several steps which need to be taken for a successful alignment job.

Step 1 Familiarize with terms, techniques and procedure.

*follow all safety rules and procedures

Step 2 Learn about the machine you are aligning.

1. Visually check coupling, pipehangers, base bolts, coupling spacing etc. 2. Check for coupling & shaft run out.

Step 3 Know the characteristics of your tool. Perform a Sag Check

A sag check is a test that determines the amount an indicator bracket will sag ata given distance.

How to perform a sag check:

Clamp the brackets on a sturdy piece of pipe the same distance they will be whenplaced on the equipment. Zero both indicators on top, then rotate to the bottom.The difference between the top and bottom reading is the sag.

Sag will always have a negative value, so when allowing for sag on the verticalmove always start the dial indicator with a plus(+) reading. For example if you

have .002" sag; when you zero your indicators on top put the needle on a +2

instead of zero to compensate for the sag.Step 4 Prepare the machine.

a. Remove all existing shims from under the feet-if old shims are to be used, clean them thoroughly.-always use minimum amount of shims.

b. Clean the base thoroughly.

-scrape and file away all rust, nicks, and burrsc. Examine the base bolts and holes.

-retap if necessary-replace bolts if necessary

Step 5 Clean mounting surface, file off nicks and burrs.

b. Check indicators for sticking and loose needle.c. Aim indicator stem directly toward center line of shaft.

Step 6 Measurement

-measure distance between the two indicators.

-measure distance between indicator and front feet.-measure distance between front and back feet.



Step 7 Layout graph paper

-mark indicator position-mark feet position.

-remember to mark + and - signs (this eliminates confusion)example: graph layout

Step 8 Preliminary Horizontal Move

The horizontal move is the part of the alignment process that aligns the shaft'scenterlines from side to side. View the machine from the pump end, zero theindicators on the left, and then rotate and read on the right. Make sure that you

always view the pump from the same direction in order for you to keep the left

and right directions correct. There is no sag compensation on the horizontalmove.

For Example: the indicator on the pump reads -8the indicator on the motor reads +10

The shafts are collinear at 1/2 the Total Indicator Reading.

Using graph paper to illustrate the position. Under the indicator position mark

the point that is 1/2 the indicator reading. (-4 for the pump and +5 for the

motor) Connect these points and extend the line past the motors feet. This willshow you how much you need to move the motor for horizontal alignment.

These indicator readings mean that you need to move the motor:

front foot .006" leftback foot .007" left



You can avoid graphing the horizontal move by zeroing the indicators on the left and

rotate them to right. Now turn the indicator needles half way to zero and begin to walk

the motor into place by moving the farthest foot toward zero and then the nearest foot.Slowly walk the motor into place by alternating the moves until you obtain two zero

indicator readings.Now begin the procedure for the vertical move. Be sure to check your equipment for

sag and soft foot.

Step 9 Check for Soft Foot

Soft foot is a condition in which one of the feet does not sit flat on the base. The foot or

the base may have been warped. When you tighten the bolt on the foot, the machinerywill distort.

Parallel Soft Foot Angular Soft Foot

How to check for Soft Foot 1. Move indicators to 12 o'clock position, depress indicators and then zero. 2. Loosen one base bolt. If indicator moves away form zero, place the amount of

shims that will slide under that foot. Retighten bolt and make sure the dial

indicator needle does not move. 3. Repeat this procedure for the remaining feet.

Step 10

Perform Vertical Move



The vertical move is the part of the alignment process that aligns the two shaft's

centerlines into their proper up and down position. Usually you will have to add orremove shims in this step. The indicators are zeroed on the top and read at the

bottom. (start with a plus + reading if you need to compensate for sag) Example:

the indicator on the pump reads -12the indicator on the motor reads +8

This means that the shafts are one half the total indicator reading from being collinear atthese points. Using a square grid graph paper to illustrate the position. Under the indicator position

mark the point that is half the indicator reading. ( -6 for pump side indicator and +4 for

the motor side indicator) Connect these two points with a line and then continue theline past the lines representing the feet on the motor. The graph now shows that thefront foot needs to have a .003" shim added and the back foot needs to have a .001"

shim added.

Now with your shims in place. Tighten all bolts and take and check your readings. If the readings are within tolerance than your equipment should be aligned.

Step 11 Tighten all bolts and recheck indicator readings.

Step 12 Remove alignment brackets.

The more you become familiar with these steps the faster you will be able to align yourmachinery.



Five Basic Errors in Shaft Alignment

Properly aligned shafts will do more to increase bearing, seal, and rotor life than any other single thingyou can do after lubrication. Unfortunately, many maintenance departments in smaller plants still thinkthat alignment is only needed for large, high-speed shafts on somebody else’s equipment. Many have noidea how to align two shafts beyond using a straight edge to get them close. Besides, the guy who sells

the couplings says that the coupling can take up to one degree of misalignment and not hurt anything.

That is a pretty gross figure. They are correct, though. They design couplings that will not wear out withthat much misalignment. The life of the coupling, though, is not controlling here. Badly aligned shafts, andby that I mean much less than the one degree of misalignment the coupling manufacturers use, will ruinthe bearings on the equipment in short order. All shafts, even low speed ones, must be aligned to within afew thousands of an inch TIR (Total Indicator Runout) if the bearings are to last for their full expected life.

Typical Types of Misalignment in Shafts

There are some tremendous systems on the market for alignment. They use lasers, computers, andproximity sensors. They will practically move the equipment and install the shims. They do no good at all,though, if they are not used by trained, qualified technicians who understand what the systems are tellingthem.

This paper does not purport to explain shaft alignment. The presumption is that the reader already hassome idea of how to align shafts using a dial-indicator set. What we want to do in this paper is to point outfive common errors made while aligning and what to do about them.

Couplings ain’t round.



Suppose we have two shafts that are perfectly aligned but one has a coupling improperly mounted on ashaft so that there is some error in colinearity of the axes. As we approach the maching the error is onlyin the horizontal direction. Let’s set up the dial indicator so that it reads the outside of the coupling thenrotate only the shaft on which the indicator is mounted, leaving the coupling still. When we get to position1 the dial indicator will be extended to, say, -0.010 inches due to the error. Turning to position 2 will bringthe dial indicator back to zero. At position 3 the indicator is compressed due the error and reads +0.010. If we believe that the coupling is square on the shaft and the axes are collinear we will believe that there isa TIR or 0.020 inches in the horizontal direction. Acting on that information will cause us to misalign theshafts by 0.010 inches – introducing vibration and potential bearing damage.

How can we eliminate that error? By rotating both shafts together. The roundness of the coupling, theroughness of its surface, and the poor mounting will be eliminated from the readings (actually, all of thosethings will cause compensating errors so that only the actual misalignment of the two shafts will beindicated by the dials.

A better way is to eliminate reading the coupling at all by using a target for your indicator that is securelymounted on the shaft. This will necessitate rotating both shafts but eliminates the need to break thecoupling, even to do rim-face readings.

Move the Driver

This seems almost intuitive – at least if you have been in the field for any time. Yet, I repeatedly have hadclients who inexplicably believed it was easier to move the driven machine. I will not argue that there is atime when the driven should be aligned to the driver. In all of industry, there are undoubtedly situationswhere this is better. As a general rule, though, it is better to move the driver that is not connected to your process than to move the driven that is.

For example, suppose we are aligning a pump and motor. The pump is connected to the process by aninlet pipe and an outlet pipe. There are some applications where the piping is connected through flex- joints but I haven’t found very many of them. Most of the time, the pump is hard-piped into the system. I



will make an assumption that you have corrected any pipe strain in the system. If not, then do that beforetrying to align the pump. You are just kidding yourself otherwise.

Once the pump has been connected to the system, any attempt to move the pump to align it to the motor will induce pipe strain; whereas, moving the motor strains nothing but the flextite on the electricalconnection – and it was made to be strained. If you move the pump and introduce pipe strain, you will end

up with a misaligned pump as soon as you start the system up. Hot fluid, cold fluid or just the movementof the fluid will begin to flex the piping system which will, in turn, move your pump, which will in turn ruinthat careful alignment you just accomplished.

Threads don’t increase Strength

At one client’s plant I gave a four -hour class on shaft alignment. At the end of the class, we went to thefield to practice on a 50 Hp pump. This was a pump that had been “aligned” by that crew the week before.The plant had been in service for about two years and the bearings had been failing on this pump everysix months. In the middle of the class, there had been some sheepish looks and, when I questioned them,they admitted that they had never heard of angular misalignment and had only been correcting offsetsince startup.

With information from the first pass of readings, the computer required a movement of the back end of themotor which was 0.010 to 0.015 more than the holes in the motor mount would allow. After some cursing,the crew began to disassemble the coupling and pull all the mounting bolts. I stopped them and askedwhat they were planning. “We have to take the motor to the shop and enlarge the holes in the feet,” wasthe answer.

There are times when the two devices may be so misaligned that that kind of action may be necessary.Needing less than 0.015 inches is not that kind of misalignment. When you run across this situation, dothis: Pull the offending bolt, take it to the shop and turn or grind the threads off in the area that is incontact with the motor foot. You can grind all the threads down to the root diameter and not effect thestrength in tension at all. On a 5/8 –11 bolt the OD at the threads is 0.614 inches. The root is 0.515inches. So, you can pick up 0.050 inches of movement with no decrease in strength by grinding thethreads.

Besides, I have seen many alignments where the computer moved the offending foot right back after thesecond pass. Enlarging the hole in the foot would have been an extreme waste of time.

2 Planes are Better Than 1



I have seen alignment techniques that suggest that the technician align first the horizontal then thevertical. I disagree with that. I believe you should be making complete passes – all four positions, andcalculating both your vertical and horizontal correction at the same time. Here’s why:

If the alignment is far out, it is better to correct both planes (horizontal and vertical) at the same time.Otherwise the requirement for positioning the indicators becomes too precise. Error will be introduced andyou will end up bouncing around the solution for any one plane.

Suppose you are nearly perfect in the vertical direction yet still grossly misaligned in the horizontal asillustrated in the above figure. If you do not place your dial indicator exactly vertically, part of the grosshorizontal misalignment will be read as vertical misalignment. This will cause you to bounce around the

solutions with each pass.

It is better to remove the error from both planes together so that this situation does not arise. With theavailability of computers, laser systems, etc. there is not reason not correct both planes simultaneously.

Reverse Indicator Works

Most experienced mechanics and engineers will shrug at that statement. Of course, reverse indicator systems work. My experience as a teacher and as a consultant belies that complacency. I have foundexperienced crews who knew nothing but rim-face techniques or who knew of RI but did not believe itworked. I had one very experienced technician tell me that RI only worked on very large shafts.

To correct this thinking, I utilize a very old technique popular and needed prior to the advent of hand heldcalculators and computers: the plotting board technique.



In it, the distance between in the indicators is plotted as X. The distance from the B indicator and the frontfoot of the moveable machine is plotted as Y. The distance between the feet of the machine is plotted asZ. So, the horizontal axis is normally in inches. The vertical axis, though, is not in inches but in thousandsof an inch.

On the A line is plotted the TIR of the A indicator in the plane being corrected (I know, I just told you tocorrect both at the same time – only, we didn’t have the calculating technology back then.) The Bindicator TIR is plotted on the B line. A straight line is drawn through them and extended all the way to theRear line. The needed correction at each foot is read off the vertical axis where the plotted line intersectsthe “foot” lines.

In the example shown the A TIR was +0.003 inches. The B TIR was +0.002 inches. The plotted linecrossed the Centerline very near the Front line and crossed the Rear line at approximately –0.0015

inches. If this was the vertical plane being measured, then the front legs would need no correction andthe rear legs would need a 0.0015 shim added to bring it up to the centerline.

Normally, when this technique is shown to the technicians, a light bulb goes on and they are able to graspand appreciate the RI technique.

RI is not right in every situation. It is just another tool the alignment technician has for getting the jobdone. Its biggest advantage is ease of set up and a balanced rotor compared to Rim-Face (RF). The RIset up is balanced and will not rotate unless made to. The RF is unbalanced and will rotate to the bottomposition unless held in place.

These five errors, although simple and basic to the experienced mechanic, are ones that I have found

many clients making – and making without even realizing there was an error involved. Teaching thesethings to an inexperienced crew or to your new craftspeople will improve your alignments and make themmore time efficient.

Benefits, Methods of Proper Pump to Motor

Alignment



By Allan R. Budris

Experience shows that many pump distress events (failures) have their root cause in the

misalignment of the pump to motor. Misaligned pumps can even consume up to 15% moreenergy input than well-aligned pumps. Even small pumps can generate big losses when shaft

misalignment imposes reaction forces on shafts, even if the flexible coupling suffers no

immediate damage. The inevitable result is premature failure of shaft seals and bearings.Performing precise alignment, therefore, pays back through preventing the costly consequences

of poor alignment. Indeed, using precise alignment methods is one of the principal attributes of a

reliability focused organization. Good alignment has been demonstrated to lead to:

Lower energy losses due to friction and vibration

Increased productivity through time savings and repair avoidance

Reduced parts expense and lower inventory requirements

Further, in order to insure good alignment, the alignment must be checked and correctly setwhen:

A pump and drive unit are initially installed (before grouting the baseplate, after groutingthe baseplate, after connecting the piping, and after the first run).

After a unit has been serviced.

The process operating temperature of the unit has changed.

Changes have been made to the piping system.

Periodically, as a preventive maintenance check of the alignment, following the plant

operating procedures for scheduled checks or maintenance.

Alignment Problems



Hundreds of technical articles and presentations have elaborated on the serious problems that are

caused by incorrect alignment between the pump and driver, such as:

Coupling overheating and resulting component degradation

Extreme wear in gear couplings and component fatigue in dry element couplings

Pump and driver shaft fatigue failure Pump and driver bearing overload, leading to failure or short bearing life

Destructive vibration events. Harmful machinery vibration is created whenever

misalignment exists. Excessive pump vibration can shorten bearing and mechanical seallife.

Pump Alignment Basics

Pump shafts exist in three-dimensional space and misalignments can exist in any direction. It has

been found to be most convenient to break this three-dimensional space up into two planes, thevertical and the horizontal; and to describe the specific amount of offset and angularity thatexists in each of these planes simultaneously, at the location of the coupling. Thus, we end up

with four specific conditions of misalignment, traditionally called Vertical Offset, Vertical

Angularity, Horizontal Offset, and Horizontal Angularity. These conditions are described at thelocation of the coupling, because it is here that harmful machinery vibration is created whenever misalignment exists.

Basic issues that must be taken into account regarding pump alignment are:

Alignment equipment sag (with dial indicators)

Cold, hot or running alignment Where to make shimming adjustments (Align the motor to the pump by shimming the

motor feet)

Soft foot problems

Type of alignment equipment

Alignment Methods

Alignment accuracy is critical to pump and driver longevity as stated above, and generally the

better the alignment the longer the pump and driver bearing life. Figure 1 shows the bestalignment that can expect from the three most prevalent alignment methods practiced in the

industrial, worldwide.

Straight Edge and Feeler Gauges

Dial Indicator

Lasers-optic



Straight Edge, Feeler Gauges

This is the easiest and least expensive method of doing alignment but it is also the least accurate.

Used primarily for very small pump / motor combinations where there is not enough room to usemore accurate but larger alignment methods. The straight edge is laid across the flanges of the

coupling hub and the feeler gauges are used between the faces of the coupling hubs. Shim

changes are estimated and the alignment is attained through a process of trial & error. It is moredifficult to attain the equipment manufacturer's alignment specifications through the use of a

straight edge and feeler gauges.

Dial Indicators

There are two basic dial indicator methods. The Single Indicator Method uses a single dialindicator to take both the rim and face reading. You can then calculate shim changes for the

motor feet to correctly align the unit. The Reverse Indicator Method uses a dial indicator on the

pump shaft to read the motor shaft, and a dial indicator on the motor shaft to read the pump shaft.You can then use mathematical formulas to calculate shim changes to correctly align the unit.

Although better then the "straight edge and feeler gauge method", the dial indicator method does

have a few shortcomings, such as:

Sagging indicator brackets Sticking/jumping dial hands

Low resolution rounding losses

Reading errors

Play in mechanical linkages

Tilted dial indicator (offset error)



Lasers-optic Devices

This state-of-the-art system emits a pulsating non-hazardous laser beam that automaticallydetermines relative shaft positions and conveys this information to its microprocessor. The

advantages of modern laser-optic alignment devices far outweigh the possible initial cost

advantages of other, more conventional methods. Reliability-focused pump users employ thisstate-of-art laser optic alignment determination method, even though it is somewhat more

complicated to set up, but it can be more accurate if properly used. The laser is especially helpful

when aligning shafts that are separated by more than a few inches. The laser systems also havesoftware that is capable of calculating the shim changes required. Once familiar with it, the laser

operator can align a pump/motor combination fairly quickly and accurately. The primary

drawback of the laser systems is cost, and in some cases their size.

Specific advantages of laser alignment tools are that: they do not require as much operator skill;

center-to-center pump alignment can be achieved without paying attention to thermal growth,

since it is possible to feed in the thermal growth data for compensation; and laser alignment can

allow the operator to check the pump when it is running and up to temperature, this is not possible with dial indicators. Other advantages for the laser are:

It is free of gravitational hardware sag

It can work with the couplings in-place or uncoupled

It is fast & easy to mount

It can detect & measure the extent of a "soft foot"

It feeds misalignment data to a microprocessor for horizontal and vertical corrections.

Alignment Tolerances

Acceptable alignment tolerances are a function of shaft speed, coupling type/geometry, and thedistance between the driver and pump shaft ends. The question then becomes, just how close

should the pump and driver shafts be aligned? How much vibration and efficiency loss will result

from the misalignment of the shaft centers? It should be noted that high-quality flexible

couplings are designed to tolerate more misalignment than is ideal for the machines involved.Bearing load increases with misalignment, and bearing life decreases as the cube of the load

increase, therefore, a doubling of the load will shorten the bearing life by a factor of eight.



There is generally little consensus among machinery manufacturers and users as to the allowable,

and/or preferred alignment tolerances. As a minimum, the recommendations of the coupling or

pump manufacturer should be followed.

Pump Alignment: Just The Facts

Proper alignment of the pump shaft with the driver can reduce vibration and significantly improve

reliability. For appropriate applications, the time, expertise and instruments needed to achieve precision

alignment (tolerances of less than 0.005 in) will prevent seal leakage and extend bearing life.

Depending on such factors as operating speed and coupling type, not all pumps will require such precise alignment. When assessing a plant's alignment needs, it helps to understand basic shaft

alignment concepts and procedures, as well as application-specific factors that dictate therequired tolerances.

Effects of Misalignment

A common misconception about pump shaft/driver misalignment is that it increases bearing load,

causing bearings to fail prematurely. In fact, except in cases of extreme misalignment, the

resulting vibration is what damages bearings and seals. Since some vibration is normal for pumps, it is best to have an experienced vibration technician determine if the vibration is due to

shaft misalignment, and whether it is severe enough to affect pump reliability.

Alignment Basics

The purpose of shaft alignment is to minimize the vibration resulting from forces transmitted

across the coupling. The goal is to have both shafts rotating on a common axis, referred to as

http://www.pump-zone.com/motors/motors/pump-alignment-just-the-facts.html





collinear. All misalignment of shaft centerlines (i.e., deviation from the collinear condition) can

be described in terms of offset and angularity.

Theoretically, two perfectly aligned shafts would rotate in the same axis, and if properly

balanced and coupled, would not generate abnormal vibration during operation. If instead the

two shafts are misaligned in the horizontal or vertical plane (or both), or are at an angle withrespect to one another, they will rotate in different axes. The amplitude of the resulting vibration

will vary, depending on such factors as the severity of the misalignment, operating speed and

coupling type.

In addition, the relative positions of a horizontal pump and driver can be viewed independently

in the horizontal and vertical planes. Reducing alignment conditions to offset and angularity,independently in the horizontal and vertical planes, simplifies manual calculation of required

"correction moves." Automated techniques for calculating corrections also use this convention.

(Vertical pumps, solid couplings and hollow-shaft motors present unique concerns and require

special procedures not discussed here.)

Alignment (or misalignment) is measured at the coupling-the point of power transmission-not at

the feet. The amount of shims to be added or removed beneath the feet does not directly indicatethe alignment condition at the coupling.

Figure 1. Alignment tolerances in relation to operating speed.



Tolerances

Alignment tolerances specify how close the pump and driver shaft centerlines should be tocollinear at running conditions. Offset tolerances are measured in thousandths of an inch (or

mils), centerline-to-centerline at the coupling. Angularity tolerances are expressed as pitch or

slope (mils/inch).

Alignment tolerances for pumps range from the "rough alignment" that a conscientious

technician can accomplish with visual indicators (accuracy of about 0.02 in) to precisionalignment (accuracy of 0.0005 in or greater). The latter requires an experienced technician and

accurate instruments (e.g., dial indicators or a laser alignment system). Accuracy of about 0.005

in can be accomplished with a simple straightedge and feeler gauge.

The degree of precision required for a specific pump/driver will depend on the pump's rotating

speed, the distance between the pump and driver shafts (spool-piece length) and the application's

thermal characteristics. The required precision increases exponentially with operating speed;

proportionally less precision is necessary with longer coupling spool pieces. For applicationswhere temperature changes occur during operation, evaluation of thermal effects is also needed

to determine target values.

Another important factor is the coupling type. Industrial users generally agree that non-segmented elastomer boot couplings produce less damaging vibration than jaw or gear couplings,

given equal amounts of misalignment. Other kinds of couplings fall between these extremes.

Figure 2. Offset and angular tolerances in relation to operating speed.



Alignment Procedures

Rough Alignment: When installing the pump and driver, experienced technicians will perform a"rough alignment" based on visual indicators. They also will ensure that all machine feet are in

good foot-plane and have 0.025 in to 0.050 in shims under them. Good foot-plane must be

established and maintained throughout the alignment procedure to avoid stressing the machinecases.

Target Values: Pumps and drivers are moving targets due to torque strains and thermal effects,so evaluation of these factors is an important step in pump shaft alignment. Just as a marksman

anticipates the location of a moving target, proper alignment procedures must predict the relative

running position of the machine cases (i.e., differences between cold and running alignment positions). These target values may be determined for the relative positions at the coupling or at

the feet.

Figure 3. Sample alignment target values.

Measurement: Alignment tolerances and misalignment are measured at the coupling, where the power

is transmitted. The simplest way to measure these parameters is with a straightedge and feeler gauges.

A taper gauge or caliper can also be used to measure angularity between the coupling faces. These

methods can achieve accuracy of about 0.005 in, which is acceptable for many pumps that operate at

1,200 rpm or less.

If precision alignment is required, careful use of dial indicator methods (e.g., rim-and-face and

reverse-dial), including compensation for bracket sag, can achieve accuracy of 0.0005 in. Thiswill suffice for most pumps that run at 5,000 rpm or slower.

Laser alignment systems accomplish the task quicker and with more accuracy, eliminating math

errors and other common mistakes. Most of these systems also provide graphics that show thedirection of the "correction move."

Regardless of the alignment method, correction moves must be determined from measured

misalignment data-whether the calculations are done manually, or automatically with a

calculator, computer program or laser alignment system. Attempts to "guesstimate" correction

moves often waste time and cause frustration.



Foot-plane: To maintain good foot-plane during the alignment procedure, both front feet should

be raised or lowered the same amount, and similarly, both rear feet should be moved in equal

amounts. Shim adjustments that would tilt the motor side to side should be avoided.

If a machine is bolt-bound or base-bound and cannot be adjusted sufficiently, it will be necessary

to move the opposite (fixed) machine case. Most calculator and laser systems provide the meansto recalculate for base- and bolt-bound conditions.

Documentation: It is essential to record pre-alignment data, target values, tolerances and finalaligned condition. This information can help maintenance personnel determine when to perform

maintenance tasks and spot developing problems that may otherwise result in unexpected, costly

failures and downtime. The documentation features included with many alignment calculatorsand laser systems may not be adequate for recording data about foundations, machine feet,

shims, coupling components and observations. If so, a paper or an electronic work order system

should be used to capture this information (see an example data form below and click here for an

enlarged version and a downloadable pdf ).

http://www.pump-zone.com/motors/motors/sample-alignment-data-form.html








Assessing Alignment Needs

Pump and alignment tool manufacturers offer "suggested" alignment tolerances, most of whichdo not consider the coupling type. But application-specific variables make a single tolerance for

pumps unrealistic. The best approach is to evaluate each installation based on operating speed,

thermal movement, spool-piece length and coupling type.

For a large 1,200 rpm pump with an elastomer-in-shear coupling, alignment with a straight edge

and feeler gauge to precision of 0.005 in would suffice. A medium-size 3,600 rpm hot water circulation pump with a jaw coupling, however, would require precision alignment with dial

indicators or a laser system. A high-temperature (400 deg F) refinery pump may have a spool-

piece coupling to accommodate thermal movement, and would require an operational assessmentof target values.

While target value assessment and precision alignment techniques could be used for any of these

pumps, the required time and expense would outweigh the benefits for the 1,200 rpm pump.

Thermal growth analysis also would be unwarranted on the hot water circulation pump, becausethe driver and pump will have similar thermal growth. Common sense dictates that evaluation of

the alignment needs of individual pumps-including coupling type, thermal changes, rotatingspeed and spool piece length-will ensure use of the most cost-effective shaft alignment

procedure.

Conclusion

Successful pump alignment requires careful planning and execution, beginning with evaluationof tolerances and target values based on pump speed, thermal characteristics, coupling type and

spacing. The technician must also be adequately trained and systematically document the entire

procedure, including the original misalignment, the final alignment condition, and anyobservations related to machine reliability. The expense or sophistication of the alignment tools-

whether laser, dial indicator or manual-will not produce the desired results if these essentials are

ignored.

Documents

Dial Indicator Alignment Procedure.docx