Rotate the shaft until the dial gauge reaches a maximum or a minimum reading. It can be resolved into a parallel offset at a given point along the fixed machine centerline and angular misalignment in both the horizontal and vertical planes. Api was formed in 1919 as a standardssetting organization and is the global leader in convening subject matter experts across segments to establish, maintain, and distribute consensus standards for the oil and gas industry. As a leading provider of precision measurement services for power. Hp horsepower is the actual or transmitted power required by the application if unknown, use the motor or turbine. Alignment check methodology for rotary equipment using caesar.
A coupling alignment tolerance is often but not always the maximum amount of misalignment the coupling will operate at before premature failure. For spacer shafts, the table gives the maximum allowable offset for each 100 mm or inch of spacer shaft length. Shaft alignment methods explained bright hub engineering. This method of piping alignment, which some questions that i need a professional advice, through your studies and experiences. The subject of shaft alignment tolerances has been touched on before but a couple interesting discussions have taken place recently during training classes. I am not the absolute know everything about everything when it comes to the installation of process equipment. Shaft alignment procedures must be followed to prevent catastrophic failure of. Dear all, a few topics which i considered will interest you guys, regarding the above description. Table of contents a what is alignment b what is misalignment c types of misalignment d method of alignment e symptoms of misalignment f pre alignment checks g tools required for alignment h alignment tolerances. Rotate the shafts from 60 to 180 degrees to determine the vertical and horizontal position of the two rotational axes at the sensors. Changes in the temperature of machines from off line to running can have a significant impact on the shaft alignment. Applying one of the balancing quality grades such as iso 1940 and api 617. Proper shaft alignment is especially critical when the motor is operated at high speeds. Recommendations for checking rotating machinery installation.
Piping stress considerations and practical remedies to overcome. Care has been taken by the authors, pruftechnik ltd, in the preparation of this publication. We would like to have a confirmation on the material that should be used for the leveling pads to be utilized under the pump. Standard industry norms for alignment tolerances are cited in table 1. View member profile send email find members topics find members posts. The goal of the alignment process is to create a straight line through the coupling, as shown in figure 1.
Straightness and flatness tolerances for ranges of nominal lengths l. Rough align rough align the machine vertically using a scale. Precision shaft alignment is possible reliable plant. As per the code if the vertical and horizontal deviation of piping flange and rotary equipment flange centerline is within 1. No, rp 686 does not address application of a dualpurpose gasket. With a loadonpad design, figure 1 the shaft is free to laterally within bearing clearance, and alignment data is difficult to obtain without temporary bearing shims to stabilize the sham with a loadbetweenpad design, figure 1 b, the shaft remains stable during the alignment procedure. Api laser tracker inspection, alignment and measurement services, along with tracker rental programs, are active in the construction of new manufacturing facilities whether associated with building construction, equipment installation or aiding preproduction product manufacturing. There are two types of misalignment, offset and angular see figure 2. The practice of misaligning two shaft centerlines at ambient. Api 686 practices shaft alignment free download as pdf file. Machinery alignment tolerance tables impact engineering.
Hello members i would like to have clarification with regards to shaft alignment tolerances mentioned in api 686 second edition dec 2009 clause 5. Preservation during operations, the equipment should be preserved and protected in compliance with the suppliers procedure. Aim to have all soft foot readings within 2 mils thou. It will also explain why it is absolutely necessary to have both the short flex and spacer shaft tolerance options when performing an alignment. These standards are useful only for shafttoshaft alignment of thermal power stations coal handling plants. Bearings, mechanical seals, packing, and couplings are all directly affected by the alignment of shaft center lines. A p i rpbdb 96 m 0732290 0553943 585 m recommended practices for machinery installation and installation design manufacturing, distributionand marketing department api recommended practice 686 pip rele 686 process industry practices copyright 2003. With feeler gauge find obvious gaps and fill them with shims, taking care of any rough soft foot condition. Link to an article discussing how to choose which tolerances to align to. They explain the concept of effective variation, actual and effective tooth size. Shaft centerline alignment is the positioning of the rotational centers of two or more shafts such that they are colinear when the machines operate under normal conditions.
Shaft alignment is the process of adjusting the relative position of two coupled machines such that the centerlines of the respective shaft form a straight line when the machine is running at normal operating temperature. A coupling alignment tolerance and a shaft alignment tolerance are different things very different things. Well that makes about as much sense as eating with your feet. It is not intended as a comprehensive guide to alignment of process machinery, nor is it a substitute for seeking professional advice or reference to the manufacturers of the machinery. The analysis of the effective variation, which is defined as the deviation allowance, for the different spline tolerance classes is presented. Flange dimension tolerances, dimension table, asme b16. Sep 17, 2009 welcome to part 1 of 3 in a series discussing rotating machinery alignment tolerances. Written by stan riddle, brad case and patrick lawrence from vibralign and originally published in the june 1. The main purpose of shaft alignment is to make sure that the center line of the motor rotor shaft coincides with the center line of the driven machinery i. I cant see anything in api 610 or api 617 for pump or. In practice, proper alignment is difficult to achieve without using alignment equipment such as dial indicators or laser alignment tools. Tolerances are generally given in the contract documents or one can refer to pfi standards es02 and es03.
Shaft alignment tolerances spacer couplings6, 7 angularity angles a and b, or projected offset offset a, offset b excellent acceptable rpm milsin mmmm milsin mmmm 600 1. Accurate alignment is vital to the operating life of rotating equipment. Shaft misalignment is responsible for as much as 50 percent of all costs related to rotating machinery breakdowns. Connection procedure alignment of process piping with. Recently we were asked what we thought of alignment at the feet. In the past i have represented the end users or have done the construction myself.
This article provides the necessary brief information to assist the site engineersfield engineers construction engineers during the first installation and connection of piping with the relevant rotating machinery. What alignment tolerances between the piping and machinery nozzles must be achieved before local heating will be used to. Good quality, precut stainless steel shims come in thicknesses, ranging from 1 mil to 120 mils. American petroleum institute american petroleum institute document provided by ihs licensee. Shaft alignment industrial wiki odesie by tech transfer. In order to prevent any grit and foreign matters from. When you have done an alignment using the alignment tolerances shown above, whether you are short coupled and using gapoffset or have a spacer shaft, you should not have any alignment related vibration. Moreover, as the name suggests, the main purpose of shaft alignment is to make sure that the center line of the motor rotor shaft coincides with the center line of the driven machinery i. Shaft alignment tolerances spacer couplings6, 7 angularity angles a and b, or projected offset offset a, offset b. Terminations shaft diameter up to 28 mm are made with tolerance j6, shaft diameters from 28 to 50 with the k6 and higher shafts diameters are made with m6. Chapter 6 provides guidelines for piping alignment as.
While engine alignment is well understood by most marine industry professionals, shaft alignment is far more esoteric and well understood by far fewer folks in the industry. These changes in the shaft alignment can be accommodated in a. If, on the other hand, you update your knowledge of shaftalignment techniques and acceptable alignment tolerances, you might be on the way to becoming more reliabilityfocused. Most shaft alignment tolerances are based on revolutions per minute rpm, so also enter that data. Mauricio, the american petroleum institute api has shaft alignment standards api 610 that are used in the petrochemical industry, and i believe the hydraulic institute has developed shaft alignment standards as well. Alignment check methodology for rotary equipment using. It is not intended as a comprehensive guide to alignment of process machinery, nor is it a substitute for seeking professional advice or.
To take an example, a machine running at 6000 rpm with a 300mm spacer shaft installed would allow a maximum offset of. If a manufacturer of a machine or coupling requires tighter alignment tolerances, those should be used. Api recommended practice 686 machinery installation and. When you opt to use your own shaft alignment tolerances instead of using the industry standards, how do you decide what to use. The fixturlaser xas and gos allow you the option to. Machinery alignment tolerance tables the suggested alignment tolerances shown here are general values based upon experience and general industry standards and should not be exceeded. Pitch diameter is assumed as a reference parameter during the analysis.
Steve chwyl, freelance mechanical specialist, planner, millwright disclaimer. The alignment standard suggested for fourdial gage method, which provides the technician the recommended approach for the quickest way with quality alignment. I dont know anything about csi equipment, but api 686 recommended practices for machinery installation and installation design covers alignment extensively. Api 686 only gives a recommended angular tolerance and nothing for offset alignment. Physical space limitations special bore or finish information and type of fit. Coal handling plant alignment standards for shaft to shaft. Sighting through as part of shaft alignment procedure eliza jaryszkami ska west pomeranian university of technology, szczecin, institute of manufacturing engineering, al. I would like to have clarification with regards to shaft alignment tolerances mentioned in api 686 second edition dec 2009 clause 5. However, i do want to share some knowledge and create conversation about this topic.
Fixturlaser alignment tools display angular misalignment as a slope rise over run in mils1 the 0. This presentation breaks down and simplifies the definitions of short flex and spacer shaft tolerances. Api recommended practice 686 process industry practices. A practical guide to shaft alignment plant services. Alignment of the shaft is necessary when the motor or driven machinery is new or when it is dismantled due to improper running. Alignment is achieved by moving the front andor back feet of one machine up, down, and sideways, until the shafts are aligned within required tolerances. For example, the only correct way to express shaftalignment tolerances is in terms of alignment conditions at the coupling, and we will describe several ways to do this. For this method it is necessary to record all four cardinal readings. Alignment api measurement and calibration services. American petroleum institute code api rp 686 provides the data for acceptable deviation from the ideal perfect alignment.
If a manufacturer of a machine or coupling require tighter alignment tolerances, those should be used. Good machine installation practices dictate that a good rough alignment between the machines should not necessitate ever having more than 100 mils worth of shims under any machine foot to achieve final alignment within tolerance. In its first 100 years, api has developed more than 700 standards to enhance operational safety, environmental protection. When shafts are aligned, the offset and the angular must be aligned. Jun 24, 2016 fixturlaser alignment tools display angular misalignment as a slope rise over run in mils1 the 0.
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