A maintenance technician at a chemical plant was asked to align a motor and a pump with a newly purchased laser shaft alignment system. Shaft position measurements were captured with the instrument. Corrections required to align the motor (assigned as the movable machine) with the pump indicated that the outboard end of the motor had to be lowered 85 mils and the inboard end of the motor had to be lowered 37 mils; there was no shim stock under the motor feet. After completely removing the motor, the technician began grinding away the baseplate. The motor was placed back on the base and shaft position measurements were captured again. Because too much metal had been ground away, the technician then added shims under the motor feet. Several side-to-side moves were made to bring the equipment into alignment.
A manufacturer of gas turbines was installing several large air compressors to expand the capacity of a system used to test jet engines. Requests for bids to install the 11,000 hp motors, gearboxes, and compressors were sent to several general contractors. Detailed specifications including instructions for installing foundations and sole plates and for correcting soft foot conditions were provided, along with rough alignment procedures and final hot and cold alignment procedures. The general contractor was told to subcontract the alignment work to companies specializing in machinery alignment. The specifications were sent to the subcontractors; however, several of the contractors submitted bids although they did not understand many of the detailed specifications. Toward the end of the project, the company discovered that the alignment work was not performed to the written specifications and payment was withheld from the contractors who performed the work.
A company that was in the process of becoming ISO 9000, 9001, and 9002 compliant requested information on certification testing for maintenance personnel who perform shaft alignment. Several employees had been certified in vibration analysis and thermography. The company wanted documentation that personnel were adept at finding and fixing problems.
A petroleum company decided to sell one of its facilities. Several prospective buyers were interested in retaining as many employees as possible. However, they wanted to retain only people who were adequately trained and were certified to do specific tasks. When asked to provide information on task certification of its employees, the petroleum company was unable to do so.
A steel company was having problems with a fairly complex multiple-element drive train. Misalignment was found to be the root cause of the failures. No one in the plant knew how to align the drive system. An alignment service company was contacted; although a technician said he could align the drive system in less than 4 hours, the job actually took several days to complete.
An electric utility company experienced several failures on a critical pump. Inhouse maintenance personnel had been using a laser shaft alignment system to measure the positions of the shafts. The pump was being driven by a variable speed hydraulic clutch. In the instruction manual, the clutch manufacturer stated that the clutch would rise upward 15 mils once it attained normal operating conditions. Maintenance personnel set the clutch 15 mils lower than the pump shaft assuming that the pump would not move from off-line to running conditions. A survey showed that the pump shaft rose upward far more than the clutch did, forcing the unit to run under severe misalignment conditions.
Equipment for vibration analysis and infrared thermography has improved dramatically over the past 20 years, and the number of people working in these areas has increased substantially. With a small investment, anyone can buy a personal computer and a vibration data collector or an infrared camera and be in business. However, the learning curve for this equipment is long and steep.
Over the past 5 years, there has been an effort to determine the skill level of people working in vibration analysis and infrared thermography through qualification and certification testing by several companies and institutions. Many companies are requiring their employees to become certified.
Certification for other tasks in the workplace such as correcting rotating machinery problems including balancing, shaft alignment, and tribology also has been discussed. With certification testing comes questions. Who has the authority to provide certification? What is the best way to determine if people are qualified to perform shaft alignment? How can trainees prove what they learn from training courses? And how qualified are contractors who are installing new rotating machinery?
Who to train and qualify
Many organizations feel that the responsibility for shaft alignment rests solely in the hands of tradespeople (mechanics, millwrights, pipefitters, and electricians). However, are tradespeople responsible for the following tasks?
Shaft alignment training should be mandatory for managers, engineers, technicians, front-line supervisors, and tradespeople to provide them with the minimum working knowledge needed to achieve accurate alignment and to know the process. Engineering and maintenance managers, rotating equipment and maintenance engineers, maintenance technicians, vibration specialists, foremen, and front-line supervisors, as well as the trades personnel, all should be trained and qualified to do their respective tasks.
Assessing and verifying knowledge and experience
Before qualification testing begins, shaft alignment knowledge can be assessed using a Field Experience Evaluation form that queries employees' or contractors' knowledge and experience on specific types of machinery. Individuals can then be tested on specific tasks to determine if they are capable or if they need supplementary training to raise the level of proficiency.
The form can be used to determine required training for personnel installing, maintaining, or aligning rotating machinery. But how can experience and proficiency be verified?
Written or oral examinations can verify the knowledge level for each item in the form. One comprehensive test might encompass every facet of shaft alignment, or a series of tests can be given for discrete blocks of information. If the overall body of information is broken down into separate blocks, personnel with little or no experience can be tested incrementally as their level of knowledge grows. The accompanying section, "Test Requirements for Alignment Knowledge Assessment," outlines possible test subjects.
Written or oral exams can test knowledge but are inadequate to determine skill level in performing specific tasks. Perhaps the most effective means to verify knowledge and skill level is to have employees perform tasks on a simulator or directly on an operating rotating equipment drive system. However, using process machinery as a test platform may not be possible. Having simulation equipment available allows testing to occur at any time without affecting production or maintenance schedules. For accurate skills assessment, test equipment must simulate real life circumstances.
Qualification and certification testing in tasks such as vibration analysis, thermography, and shaft alignment is necessary. Establishing the requirements for qualification or certification can be accomplished by appraising the experience level of personnel through an evaluation form that addresses all aspects of the task. Skills of each individual can then be assessed and appropriate training can be administered. Written or oral exams and task simulation tests can be conducted to determine the true proficiency of personnel. MT