Machinery Component Maintenance and Repair Part 6 pps

190 Machinery Component Maintenance and Repair Appendix 4-B Specifications for Cleaning Mechanical Seal Pots and Piping for Centrifugal Pumps 191 192 Machinery Component Maintenance and Repair Process Machinery Piping 193 Appendix 4-C Detailed Checklist for Rotating Equipment: Pump Piping 194 Process Machinery Piping 195 This page intentionally left blank Part II Alignment and Balancing This page intentionally left blank Chapter 5 Machinery Alignment* For most rotating machines used in the process industries, the trend is toward higher speeds, higher horsepowers per machine, and less sparing. The first of these factors increases the need for precise balancing and alignment. This is necessary to minimize vibration and premature wear of bearings, couplings, and shaft seals. The latter two factors increase the economic importance of high machine reliability, which is directly depen- dent on minimizing premature wear and breakdown of key components. Balancing, deservedly, has long received attention from machinery man- ufacturers and users as a way to minimize vibration and wear. Many shop and field balancing machines, instruments, and methods have become available over the years. Alignment, which is equally important, has received proportionately less notice than its importance justifies. Any kind of alignment, even straightedge alignment, is better than no alignment at all. Precise, two-indicator alignment is better than rough alignment, particularly for machines 3,600 rpm and higher. It can give greatly improved bearing and seal life, lower vibration, and better overall reliability. It does take longer, however, especially the first time it is done to a particular machine, or when done by inexperienced personnel. The process operators and mechanical supervisors must be made aware of this time requirement. If they insist on having the job done in a hurry, they should do so with full knowledge of the likelihood of poor alignment and reduced machine reliability. Figure 5-1 shows a serious machinery failure 199 * Main source: Malcolm G. Murray, Jr., Alignment Manual for Horizontal, Flexibly- Coupled Rotating Machines available from publisher, Murray and Garig Tool Works, 220 East, Texas Avenue, Baytown, Texas 77520; Tel. (281) 427-5923. Adapted by permission. Certain portions of this chapter, e.g., laser-optic alignment and some of the alignment tol- erance criteria, are from other sources. [...]... with the laser-based OPTALIGN® and smartALIGN® systems The foregoing electronic systems are popular, and have advantages in speed, accuracy, and ease of use They have disadvantages in cost, usability under adverse field and hazardous area conditions, pilferage, 224 Machinery Component Maintenance and Repair sensitivity to damage from temperature extremes and rough handling, and availability to the field... at the top of the machine shaft, and an equal, but opposite, force when the indicator bracket and shaft combination is rotated to the down position, 180° removed In any event, let us assume that we obtain readings of 0 and +0. 160 in at the top and bottom vertical parallels respectively We correct for sag in the following manner: 2 16 Machinery Component Maintenance and Repair Figure 5-14 Sag compensator... preference and custom will naturally influence the decision, but here are some basic guidelines to follow Reverse-Indicator Method This is the setup we prefer for most alignment work As illustrated in Figure 5-9, it has several advantages: 2 06 Machinery Component Maintenance and Repair Figure 5-3 Two-indicator face -and- rim alignment method Figure 5-4 Three-indicator face -and- rim alignment method Machinery. .. excessive for the coupled machinery A better guideline is illustrated in Figure 5-2, which shows an upper, absolute misalignment limit, and a lower, “don’t exceed for good longterm operation limit.” The real criterion is the running vibration If 204 Machinery Component Maintenance and Repair Figure 5-2 Misalignment tolerances excessive, particularly at twice running frequency and axially, further alignment...200 Machinery Component Maintenance and Repair Figure 5-1 Machinery damage caused by bearing seizure Bearing seizure was the result of gear coupling damage, and gear coupling damage was caused by excessive misalignment, caused by piping forces which started with piping-induced misalignment, progressed to coupling distress, bearing failure, and finally, total wreck Prealignment... top would be plus 0.0013 in 218 Machinery Component Maintenance and Repair Example 3 This will determine sag for “3-Indicator Face -and- Rim Setup” shown in Figure 5-4 Set up the jig to the same geometry as for field installation but with rim indicator only and roll 180° top to bottom on pipe to get total single indicator rim sag (Step 1) Zero rim indicator on top and add or “lay on” face indicator,... compared to face -and- rim, which mounts two indicators per bracket (Face -and- rim can do it with one per bracket if we use two brackets, or if we remount indicators and rotate a second time, but this is more trouble.) There are some limitations of the reverse-indicator method It should not be used on close-coupled installations, unless jigs can be attached 210 Machinery Component Maintenance and Repair behind... failed components such as bearings, couplings, and seals can also indicate the need for improved alignment Figure 5-2 can be applied to determine allowable misalignment for machinery equipped with nonlubricated metal disc and diaphragm couplings, up to perhaps 10,000 rpm If the machinery is furnished with geartype couplings, Figure 5-2 should be used up to 3 ,60 0 rpm only At speeds higher than 3 ,60 0 rpm,... as for face-andrim Laser-Optic Alignment In the early 1980s, by means of earth-bound laser beams and a reflector mounted on the moon, man has determined the distance between earth and the moon to within about 6 inches Such accuracy is a feature of optical measurement systems, as light travels through space in straight lines, and a bundled laser ray with particular precision Thus, critical machinery alignment,... the weight of the fixture and the dial 214 Machinery Component Maintenance and Repair Figure 5-12 SmartALIGN® system (Source: Prüftechnik, A G., Ismaning, Germany.) indicators Although sag may be minimized by proper bracing, sag effects should still be considered in vertical alignment To determine sag, install the dial indicators on the alignment fixture in the same orientation and relative position as . 190 Machinery Component Maintenance and Repair Appendix 4-B Specifications for Cleaning Mechanical Seal Pots and Piping for Centrifugal Pumps 191 192 Machinery Component Maintenance and Repair Process. advantages: Machinery Alignment 205 2 06 Machinery Component Maintenance and Repair Figure 5-3. Two-indicator face -and- rim alignment method. Figure 5-4. Three-indicator face -and- rim alignment method. Machinery. prevent the attainment and retention of good alignment. Here is a list of such items and questions to ask oneself: 200 Machinery Component Maintenance and Repair Figure 5-1. Machinery damage caused