ALIGNMENT - LASER ALIGNMENT METHOD

 ALIGNMENT - LASER ALIGNMENT METHOD

• The laser alignment method is considered a precision-based performance technique that provides a faster, more accurate way to align equipment.

• It is ideal for alignment of equipment over long distances, and it is less prone for user error. Because of the range of technology between various manufacturers, the steps for laser alignment are not discussed in detail in this article.

PROCEDURE:

• laser alignment system installed on a pump and electric motor. The system contains a laser diode and position sensor on one mounting bracket.

• The diode emits a pulsating, non-hazardous, laser beam that is directed at the opposite bracket. The opposite bracket contains a prism that redirects the laser beam back to the position sensor. Like other shaft alignment techniques, the shafts are rotated to determine the vertical and horizontal readings for angular and parallel misalignment.

• The shaft positions and readings are automatically provided to a small computer. The computer then calculates the relative movement required at the feet of the moveable machine.

• A major advantage of the use of laser alignment is the precise measurement of misalignment. Laser alignment can detect misalignment to ±0.00004”. In addition, with the use of laser alignment, bar sag concerns are eliminated.

• However, there are drawbacks and limitations to the laser alignment method. Laser alignment equipment typically costs more than $10,000. Service companies or those companies with many pumps or large pumps are the primary buyers of laser alignment equipment.

• The environment in which the laser alignment equipment is used is also a limitation. The atmospheric temperature must be between 32° and 131° Fahrenheit for the use of laser alignment. The environment must also be free of steam, dust, or air currents.

• These detractors will prevent the reading of the laser beam properly. However, it is possible to use a plastic pipe to shield the beam from the steam, dust, or air currents.

FINAL CHECKS AND WORK CLOSEOUT :

After the equipment has been aligned, some additional tasks and checks should be performed.

• Make sure that each shaft turns freely with the coupling hubs installed.

• The safety equipment should be removed and the equipment energized

• The driver should be “bumped” to check for proper rotation.

• Reinstall the safety precautions and complete the assembly of the coupling per the installation instructions.

• Rotate the coupled shafts to ensure they turn freely.

• Install the coupling guards per OSHA or applicable requirements.

• The safety equipment should be removed and the equipment energized.

• Once the pump is ready to operate, the pump and piping that has been drained should be filled. As the pump and the system piping is filled, observe for any piping distortion due to improperly supported piping. Poorly supported piping may cause misalignment.

• After the piping is installed, the pump unit is operated under normal conditions and is thoroughly warm, stop the pump unit to recheck alignment while it is warm. This also ensures that there is no additional pipe strain.

• If additional alignment is required of more than 0.002” from the pipe free condition, the additional piping strain should be corrected. Additional discussion on piping installation can be found in another article.

• For high energy and petroleum pumps, the pump and driver feet are drilled and doweled at two locations, near the thrust bearing end, after the final alignment is complete and meets the specifications.

• Documentation of the alignment is important to the installation and operation of the equipment. Make a record of the final alignment tolerance on an alignment form or data sheet. This should be placed in the equipment’s history file. This provides not only proof of final condition, but allows a starting point and historical data for the future.

• For work done in the future, this information will allow for the alignment to be done quicker and smoother, saving set up time. In will also provide a basis to allow for measurement of operational time.

• Reporting or recording sheets can be developed to include information on soft feet, pipe stress and strain, coupling and shaft runouts, installation conditions such as bolts being found loose, and specifying the initial, desired, and final alignment information.

• The sheet should also provide a location for identification of the persons completing the work to be documented. This places responsibility of quality work on individuals, and provides learning opportunities if a failure occurs.

• Reported data allows for troubleshooting and root cause analysis of equipment failures. The data can be used to compare the “as discovered” condition and the “as completed” condition. This can be particularly useful for equipment with chronic abnormal behavior.

• Another useful tool for recording data are digital photos. Pictures of the shaft, coupling, base, and foundation conditions can be stored. These could be used in the future during set up to determine any special needs or how the installation was left.

• Although alignment should not be scheduled to be rechecked with the frequency of preventative maintenance procedures, it should be rechecked when observations are made in regards to the settling of the base, foundation, or soils, changing of the piping system, process changes, or seasonal temperature changes.

• For a new installation, the alignment should be scheduled to be rechecked 3-6 months after the initial installation and alignment.