10 Steps for Proper Pump-Pipe Alignment 01 preface
Piping issues directly affect a pump's life and its performance. With an initial, common-sense investment and proper attention to details, the p umps will last longer, with fewer failures of seals, shafts, bearings and couplings. More equipment uptime and less lost production will result in significant cost savings and fewer headaches.
02 Occasionally, anchors (only if NO thermal growth, which is rare) can be used for the pump piping.
At this point the pipe should be securely anchored just before the last spool, to prevent future growth toward the pump’s flanges. The piping lay out should not be finalized until certified elevation drawings are received from the engineering group or from the pump vendor. Once the
final certified drawings are received, the final isometrics can be completed and the piping takeoff can be performed. The delivery of the equipment can either be early or it can be late in arriving at the site. When the equipment is late it is critical to have certified elevation prints of the equipment. The certified prints ensure that the isometrics required for the piping takeoffs can be made without impacting the construction schedule. If the equipment is early, it will arrive at the site before the construction team needs it for installation. Preparations must be made for lon g-term storage. Using oil mist lubrication is customary to keep the equipment in as-shipped condition while it is stored. The pressurization of the bearing housing and the casing with just 10 to 20 H2O pressure prevents moisture and contaminants from entering the sealed areas and damaging the components. In addition, early delivery of equipm ent to the site allows for the verification of the actual measurements.
03 Rough Alignment Phase
Note that the motor and the pump are not yet coupled and the base plate is still sitting free, not grouted.
A. Correct configuration - Sliding support does no t keep the piping from sliding up/away. up/awa y. B. Piping is restrained (cannot slide up/away) with high thermal expansion loads. C. "Anchor" will allow pipe to expand ex pand toward/into the pump. This is a problem, causing high axial loading.
04 Base plate Leveling Pads and Grout Location
Once rough alignment has been completed, remove the equipment (pump, motor gearbox) from the base plate. Level the base plate to a maximum out of level of 0.025 inch (0.06 millimeter) from end to end in two planes. Use machined pads as the base for the leveling instruments. Inspect the foundation for cleanliness, and if no t clean, use a solvent to remove grease and oil.
05 Typical Typical Anchor Bolt and Leveling Leveling Wedges Wedges
Allow time for the cleaning substances to evaporate. Form the base using the appropriate app ropriate techniques to allow for the weight, temperature rise and fluidity of the grout material. Use epoxy grout to secure the base, and allow the grout to cure, following the grout manufacturer’s recommendations. This normally requires 24 hours at 80 F (27 C). Remove the forms and clean all sharp residue and edges from the foundation.
06 Potential bolt-bound Situation Due to Tight Tight Clearances Between Bolt, Feet and base
The rough alignment step, mentioned above, is critical to minimize the changes that will b e required to appropriately fit the piping to the pump. At the last stage, when the th e final spools are installed, the final alignment will be achieved with small ad justments. This will minimize the adjustments required on the motor feet/bolts. Unfortunately, motor hold-down bolts are often too tight and allow for only small adjustments to the motor before b ecoming bolt bound. Motor manufacturers could improve this situation significantly if motor feet were slotted by design rather than drilled for bolts. Figure 5 shows the tightness of space available to insert the foot hold-down bolt. This illustrates once again why good alignment at Step 3 can save time and the cost of having to alter motor feet (which can be a nightmare) b y slotting or reaming.
07 Reinstall the Pump and the Motor on the Base plate.
Reinstall the pump and the motor on the base plate. Rough align the equipment again, using a reverse indicator, laser alignment or similarly accurate technique. It should now be easy to finetune the motor movement within the allowable alignment target without becoming bolt bound. This is possible because of completion of the rough alignment during Step 4. Note: Never install shims under the pump feet. If the shims are lost or misplaced then alteration to the piping may be
required to get the pump within the required alignment specification. The normal procedure is to place 0.125-inch (3.2-millimeter) thick shims under the motor feet. feet. This allows for adjustments that will be required during final alignment.
08 Final Connection of the Suction Piping
Make up the final spool pieces p ieces for the suction and discharge spaces. Bring the piping to the pump now.
09 Final Piping
In figure, anchor is placed incorrectly. It will restrain the pipe from freely moving away from the pump during thermal growth. The pipe will expand from the anchor into the pump. (See discussion in Step 2)
As a final alignment step, bring the piping to the equipment; take final measurements, tack weld the spools in place. At this time the spools can be removed and taken back to the hot work permit area to finalize the weld. Leave a square and parallel gap between the flange faces. The gap should be wide enough to accommodate the size of the gasket required, plus 1/16 - 1/8”,
depending on piping sizing. (This is the only distance over which the piping will be pulled. However, because it is properly anchored before the spool pieces, this length is short, and stresses are minimized). minimized). Final align the equipment, taking into into account hot and cold operating conditions, using two indicators on the pump shaft coupling area.
10 Overhead View of Motor and Pump
As the piping is tightened into place, the shaft must not be moved more than 0.002 inch (0.005 millimeters). Otherwise, modify the spool pieces until the piping misalignment is fixed. Several conditions are common when piping is misaligned. Some of these conditions are the mechanical seal and/or the bearings running hot and other component failures. A quick analysis anal ysis of the failed parts will clearly show the signs of piping misalignment. misalignment. To make a final confirmation of the symptoms, unbolt the piping while measuring the movement in the vertical and horizontal plane. Again, piping that moves more than 0.002 inch (0.005 millimeter) mi llimeter) must be modified to correct the situation.
11 Piping Alignment Alignme nt Verificat Verification ion
Place an indicator in the horizontal and vertical planes, using the motor and pump coupling. Uncouple the pump and motor, while watching the indicators for movement. S tart unbolting the flanges, and continue watching for movement in the indicators. If the needle jumps more than 0.002 inch (0.005 millimeter) the piping has to be modified to improve the pump’s performance.
