Improving Machinery Reliability 3 Episode 3 pot

64 Improving Machinery Reliability Sneak analysis identifies the proper and improper operation of a system’s hard- ware and software. The analysis provides a systematic, consistent, and thorough review of the system’s current and logic paths, down to the individual statement and component level. Sneak analysis is not restricted to critical functions (as are many other analyses) but analyzes the complete system, function by function. The analysis will identify the cause and recommend a solution to a sneak condition, design con- cern, or document error before the problem occurs. If left undetected, sneak condi- tions occurring during testing usually result in program delays to the project. The sneak analysis process generates detailed functionally oriented patterns, called network trees, of the circuitry and software that can be reviewed individually or in groups to understand the system. These network trees not only make sneak analysis possible, but are a powerful tool in reducing the cost and improving the quality of other reliability and safety analyses, such as Failure Mode and Effects Analysis, Hazard Analysis, Fault Tree Analysis, Common Cause Failure Analysis, or Mean-Time-Between-Failure Analysis, which may be specified on a project. The major benefits derived from the performance of sneak analysis are: 1. Savings of overall project dollars. 2. Increased confidence in system safety, reliability, and operability through inde- 3. Fewer system development delays. pendent design verification. Identification of sneak conditions early in the project life cycle can provide cost savings as a result of changing a circuit or logic path on paper-rather than changing actual hardware or software. Empirical data obtained after performing a sneak analy- sis demonstrates that increased reliability and operability of the system occur when corrections for identified sneak conditions are made. Selecting a Pump Vendor The broad principles governing the selection of major machinery vendors were stated earlier in the chapter. How these principles can be applied most advantageous- ly is again best illustrated in a typical example. Take pumps, for instance. An up-to-date edition of Thomas Register of American Manufacturers will list dozens of pages of pump manufacturers. Their detailed product listing contains another 100 or so pages ranging from “Pumps, Acid,” to “Pumps, Wine.” Even after reducing the potential bidder’s list to manufacturers of refinery-type centrifugal pumps, there remain some 20-30 vendors who could be invited to bid on a given project or for a given pumping service. Were all of them to be considered, much time and money would be spent on preparing bid specifications, providing the neces- sary vendor liaison, and finally evaluating the profusion of bids received. I The need to limit bidding to a few capable vendors is quite evident. But what con- stitutes capable vendors? What criteria should be applied to narrow down the selec- tion to manageable size? How many bids are manageable? This segment of our text Vendor Selection and Bid Conditioning 65 attempts to give guidance in this regard. It explains selection procedures that have given satisfactory results in a large number of major refinery and chemical plant construction projects. More important, though, it shows how vendor selection and equipment selection criteria interact and must be given simultaneous consideration. Standardization Within What Limits? A petrochemical plant obviously would not find it practical to purchase equipment from boo many manufacturers. Spare parts identification, procurement, and ware- housing are expensive and leave margin for error. Also, it would be progressively more costly and difficult to train mechanical workforces for full proficiency in too many equipment types or models. On the other hand, standardizing on too few manufacturers may deprive the user of optimally selected equipment. There is obviously no single manufacturer of cen- trifugal pumps who can lay claim to products that are consistently more efficient, easier to maintain, and more rugged than competitive equipment. Experience shows that two or three vendors could adequately cover the on-site pumping services of a typical petrochemical plant. Five or six manufacturers should be invited to submit bids, and two or three of these subsequently selected for con- tract award. Off-site pumps, frequently of ANSI or ISO-type, could be selected from one additional vendor among those who had been invited to bid. Highly specialized centrifugal pumps for critical services, such as high-pressure boiler feedwater or pipeline supply pumps, may have to be purchased from the most experienced source, regardless of whether the vendor is among those selected for on- site and off-site pumps. Purchase of these special pumps should be handled separate- ly on an individual basis, rather than being lumped with other pumps. Assessing Vendor Experience Three principal characteristics identify a capable, experienced vendor: 1. He is in a position to provide extensive experience listings for equipment offered. 2. His marketing personnel are thoroughly supported by engineering departments. Both groups are willing to provide technical data beyond those that are custom- arily submitted with routine proposals. 3. His centrifugal pumps enjoy a reputation for sound design and infrequent main- tenance requirements. With a large: project involving 200-300 or more pumps, it is often necessary to delegate to the contractor’s equipment engineers the responsibility of verifying ven- dor experience with other users. For certain critical services (e.g., high-pressure boil- er feedwater pumps, large cooling-water pumps, multistage pipeline or feed pumps, etc.), the owner’s engineer would be well advised to check for himself. When 66 Improving Machinery Reliability procuring pumps that are required to comply with the standards of the American Petroleum Institute (Le,, API 610), a capable vendor will make a diligent effort to fill in all of the data requirements of the API specification sheet. However, the real depth of his technical know-how will show in the way he explains exceptions taken to API 610 or to supplementary user’s specifications. Most users are willing to waive some specification requirements if the vendor is able to offer sound engineering rea- sons, but only the best qualified centrifugal pump vendors-those from whom you want to purchase-can state their reasons convincingly. Concentrating on Problem Applications In assessing vendor experience, the engineer responsible for vendor selection should concentrate on pumping services that have a history of being troublesome. The approaches proposed by the various bidders for solving typical problem applica- tions may differ drastically and allow rapid separation of sound proposals from potentially troublesome ones. One of the most common problems in pump application is insufficient net positive suction head available. Often this is not realized until vendors’ proposals have been solicited and some vendors have failed to meet the conditions. When NPSH is insufficient, the plant design should be reviewed to determine whether decreasing the length or increasing the size of the suction line is feasible. Raising suction-vessel elevations is another possibility, but economics may dictate selection of pumps designed especially for low NPSH. When NPSH availability is limited, the pump vendors, of course, will offer double suction pumps when possi- ble. Also to be considered are inducer-type impellers, but it must be realized that inducers may have a limited flow range relative to a non-inducer-type pump. Also, inducers should never be used in erosive services. Pump performance deteriorates rapidly as the effectiveness of the inducer is reduced by erosion, and cavitation begins to take place. Another solution to NPSH problems is to use a vertical deep-well pump. In order to minimize maintenance problems with this type of pump, each proposed pump should be checked for applicable service experience, with attention to exact model numbers, similar pumpage characteristics, and process conditions. High-head, low-capacity ser- vices also pose problems to engineers selecting pumps. In general, four types of pumps are available for this application: multistage horizontal centrifugal, multistage vertical centrifugal, reciprocating, and single-stage high-speed centrifugal. For process units in continuous duty, experience has shown that multistage vertical and reciprocating-type pumps require more maintenance than the other two types. If a pump must handle a wide range of specific gravities, or if the fluid is particularly vis- cous, a reciprocating pump may be the only answer. If there is limited NPSH avail- able, a multistage vertical pump may be required. But for the bulk of high-head, low- capacity applications, serious consideration should be given to high-speed pumps, with the multi-stage horizontal centrifugal pump a good second choice. Vendor Selection and Bid Coriditionirig 67 Mechanical Seal Selection and Evaluation Pump-application engineers will generally agree that seal and seal environmental system selection on many pumps is becoming more complex and time consuming than pump selection.’2 Still, an average of only 10%-35% of the allotted pump-engi- neering time is generally spent on the mechanical seal system.13 Looking at the cost of seal failures and such consequences as major fires, release of toxic materials, and unit downtimes, there is reason to believe that more time should be spent on seal sys- tems design. But before we decide who should spend this time, we should examine the various selection practices prevalent in the petrochemical industry. Seal selections made entirely by the pump vendor have generally proven to be least reliable. The pump vendor is concerned that his competitor will underbid him, and thinks that the engineer selecting the pump will only look at the initial, installed cost without giving credit to the potential run-length extension and maintenance cost avoidance of superior seal components or seal system designs. Consequently, the least expensive seal is often selected, leaving plant operations or maintenance bur- dened with an inherently weak seal. Furthermore, pump manufacturers seldom receive experience feedback on seals furnished with their pumps. Seal selection by the pump vendor alone should thus be discouraged. Contractor’s or user’s standards have generally been applied with somewhat high- er success. Unfortunately, many of these standards are full of generalities and give little guidance on specific requirements. Very often the stated requirements do not separate barely acceptable from truly successful seal systems. Lack of specific guid- ance in an otherwise well-intended specification may significantly impair its useful- ness and deprive the user of a low-risk sealing system. Optimum seal selection practices should make extensive use of vendor experi- ence. These practices must encourage the seal vendor to use his own gland design and to recommend seal systems, not just seals. To properly advise the user, seal ven- dors require full information on product composition, process conditions, crystalliza- tion temperatures, solids entrainment, and the like. All of these data are highly rele- vant if proper selection is to be ensured, and withholding data for “security” reasons may cost the user dearly. Optimum seal selection consists of the following steps: All relevant data must be disclosed to the seal vendor. If security is truly a valid concern, disclosure should be preceded by signing confidentiality agreements. At least three and preferably four major seal manufacturers with strong and capa- ble representation in the user’s geographic location should be invited to submit bids. The user should screen and verify vendor capability by such criteria as ability to furnish engineered seal components, e.g., special pumping screws instead of ineffective pumping rings, and by vendor’s willingness to stock appropriate spares in the user’s geographic area. The bid invitation should clearly state that the user is interested in buying a seal sysrem, not just a seal. 68 Improving Machinery Reliability The bid invitation should instruct the vendor to propose a minimum of seal types. For example, better-than-necessary seal-face materials should be offered for some services, or bellows seals should be considered for an expanded range of applica- tions in order to reduce the user’s spare parts inventory. Proposals obtained from the various bidders must be examined critically for tech- nical differences, and pertinent deviations should be noted for follow-up by the user’s resident expert. These technical differences must be investigated by request- ing that vendors submit experience data. These data should include the names of other users who may be contacted to obtain verification of satisfactory experience. The user’s resident expert should make these contacts. Whenever possible, seal selection and evaluation procedures should make use of in-house feedback as to principal reasons for seal failures at that location. These data should be discussed with the vendor and solutions proposed. The user’s priorities should be clearly established and transmitted to potential seal vendors. Safety, long life, standardization, and ease of maintenance all precede cost in order of importance. These last topics merit further elaboration. Experience shows that the emphasis should clearly be towards standardization without sacrificing reliability. Seals should be cartridge seals that are simple to install and maintain. They should not be vulnera- ble to minor deviations in pump operation or properties of pumpage. Indeed, a given seal should suit the needs of many pumping services so as to reduce spare parts inven- tory, streamline training requirements and leave little room for maintenance errors. These goals can be met with a well-defined selection strategy. Such a strategy may well result in the added bonus of greatly increased seal reliability and consider- ably lower maintenance expenditures for most petrochemical plants. Many major manufacturers of mechanical seals have indicated their support and willingness to cooperate in implementing our selection strategy. Specifically, this strategy requires the development of bid request information that asks the seal vendor to identify opti- mum seal configurations. Principal features of optimum seals are highlighted in the following pages; for additional details see Chapter 13. Development of Bid Request Package The development of bid request information is a key element in a selection strate- gy leading to the procurement of mechanical seals that comply with the user needs previously outlined. Bid requests must be forwarded to several experienced seal manufacturers and must clearly state that the manufacturer should submit cost pro- posals for only those services where his seal selection is backed by solid experience. His inability to furnish seals for some services should in no way disqualify him from submitting bids for those services where he is competent to provide a good product. To begin with, the user should assemble API data sheets for the various pumps that need mechanical seals. This pump tabulation must include and disclose all of the fluid properties and operating parameters known to the user. With disclosure thus going beyond the typi- Vendor Selection and Bid Conditioning 69 cal contents of API data sheets, the seal manufacturer can be requested to list the “operating windows” within which the proposed seal will function reliably in the pump tentatively selected. It is to be understood that the “operating window” refers to the actual seal with the seal materials, balance ratio, flush plan, stuffing box lay- out, etc., selected and disclosed by the vendor. Notice also that the pumps are desig- nated “tentatively selected” because even a capable seal vendor may be unable to offer his optimum seal for a given pump. Should this be the case, it might be appro- priate to consider selecting a more suitable pump model for the intended service. As mentioned earlier, it is recommended to mail the bid request information to three or four capable mechanical seal manufacturers. Their response should be criti- cally analyzed to ferret out significant deviations among the various proposals. These deviations may range from materials of construction to different API flush plans and from differences in basic configuration to differences in application phi- losophy of stationary vs. rotating seal members. Reconciling the deviations or differ- ences will assist the engineer responsible for final selection in determining whose seal offer has the best chance of meeting the user criteria highlighted earlier. Desirable Design Features identified Evaluation of the various bids is made easier by recognizing desirable design fea- tures incorporated in mechanical seals. Some of these merit closer consideration. Cartridge Construction. Cartridge seals are designed for rapid installation on and removal from pump shafts. The cartridge seal is an arrangement of seal components on a shaft sleeve and in a seal gland constituting a single unit that is usually assem- bled and pre-set at the factory. Both bellows and spring-type seals can be cartridge- arranged if the pump stuffing box is large enough. Cartridge seal units offer major maintenance advantages. Replacement is rapid and there is far less risk of assembly error and assembly damage than with conven- tional mechanical seal mounting. API 682 requires that cartridge seals be selected for typical pumps in petrochemical plants. Silicon Carbide Hard Face Material. Heat generated at the seal faces must be rapidly conducted away if fluid vaporization and resulting problems are to be avoid- ed. Depending on service conditions and pump design, either the rotating or station- ary seal ring must be counted on to dissipate as much frictional heat as possible. High thermal conductivity and hardness make silicon carbide the preferred seal face material in many of the more severe applications. Placement of 0-Rings. An advantageous seal design recognizes that O-ring life can be reduced by close proximity to the heat source, by swelling due to chemical attack, and by operation in a dynamic mode, especially in the presence of erosive materials. Going to PTFE chevrons or wedges may allow operation at higher temper- atures and reduced risk of chemical attack, but will lead to fretting of metal surfaces in contact with it. Bellows seals eliminate many of these problems by using static 70 Improving Machinery Reliability secondary sealing. Seals with spring loaded running faces are forced to use dynamic means of secondary sealing which could, in some instances, be more prone to fail- ure. This potential problem can be overcome by selecting "stationary" and/or gas seal designs. In a stationary seal, the spring-loaded face is not rotating. Mechanical Design Considerations. Important differences can exist in the mechanical designs of competing vendors. For instance, execution E of Figure 2-7 shows the method of clamping rotating hard face (1) against shaft sleeve (2) of a sta- tionary bellows seal assembly. This clamping method ensures perpendicularity between shaft centerline and rotating seal faces. However, this clamping method also invites distortion at the running faces. Execution F tends to avoid distortion by mounting the rotating hard face in a resilient backing ring (3) and by pulling mount- ing ring (4) against collar (5). Two different clamping methods are shown in Figure 2-8. Both of these methods were devised to eliminate distortion of running faces. However, in execution G the collar is set-screwed to the shaft or shaft sleeve, whereas in execution H the mating ring carrier is set-screwed to the shaft or shaft sleeve. Experience shows that perpen- EXECUTION "E" _ EXECUrlON "F" I Figure 2-7. Two different mounting meth- ods for rotating hard faces in mechanical seals. MATING RING CARRIER Figure 2-8. Mechanical seal face clamp- ing methods devised to reduce risk of distorting rotating face. MATING RING CARRIER Vendor Selection and Bid Conditioning 71 dicularity and seal setting accuracy are more difficult to achieve with the clamping method indicated as execution G in Figure 2-8, which requires very careful adjust- ment of cap screws inserted through the collar. Another interesting difference exists in the carbon holders of the more conven- tional mechanical seals. The upper half of Figure 2-9 shows a lock ring (1) executed with a set screw (2) that engages a slot in carbon holder (3). Under certain service conditions, contact between set screw and slot may cause a wear pattern that may prevent proper seal operation. Moreover, tightening of the set screw can distort the relatively thin lock ring and cause contact or interference between lock ring OD and carbon holder ID. The construction features shown in the lower half of Figure 2-9 would tend to eliminate both of these potential problems by providing an axially ori- ented drive pin (4) and a considerably heavier lock ring (1). Both designs shown in Figure 2-9 deserve credit for presenting relatively smooth, low turbulence surfaces to their respective fluid environment. This is largely accomplished by locating the springs on the atmospheric side of the seal. Whenever possible, seals should avoid having the spring (or springs) immersed in the fluid. Figure 2-10 shows two of several seals that probably give excellent service in many services and applications. These seals use one or more stationary springs and incorporate several desirable features: a cartridge arrangement for ease of instal- lation; the single non-rotating spring shown with the design in the top half of Figure 2-10 is arranged to operate away from the product; a bronze spring retainer (1 1) serves as a throttle bushing; and the relatively clean profile inside the stuffing box Figure 2-9. Two conventional mechanical seals with carbon holder driven by modified set screw (upper half) and horizontal pin (lower half). 72 Improving Machinery Reliability reduces seal drag. (Note that rotating components are identified with even, and sta- tionary components with odd numbers.) Except for using several springs, the seal design shown in the bottom half of Fig- ure 2-10 appears to be quite similar to the design shown in the top half. Both seals incorporate the desirable features of many similar stationary seal designs: Self-squaring faces. This feature may result in appreciably better seal life for pumps with excessive shaft deflection or pumps operating with nominal shaft deflection at high speeds. Non-flexing springs. Spring life extension and long-term, uniform pressure can be expected. Pre-assembled cartridge construction. These seals can be shipped with the gland plate in place. No field measurements or settings will be required. However, a closer look will show functional differences in the arrangement of the O-ring (3). It could be argued that progressive wear of the seal faces shown in the upper half of Figure 2-10 will cause the O-ring to make sliding contact with a clean portion of part (9), whereas advancing the stationary seal face in the lower half of Figure 2-10 will cause the O-ring (3) to slide over a wetted and potentially contami- nated portion of the gland plate (15). Figure 2-10. Two different stationary seals with non-rotating springs located away from pumped liquid. Vendor Selection and Bid Conditioning 73 Functionally similar features can also be found in an intermediate range of bel- lows seals as shown in Figures 2-1 l and 2-12. Rotating bellows seals tend to be self- cleaning by virtue of centrifugal action. As mentioned earlier, they do not incorpo- rate sliding (dynamic) elastomers. Instead, they use static secondary sealing means. Figure 2-1 1. Bellows seal per API 682. (Courtesy Flowserve Corporation.) \ Figure 2-1 2. Cartridge-mounted bellows-type mechanical seal. (Courtesy Borg-Warner Seals.) [...]... 1.64E-t- 03 1.668+ 03 1.688+ 03 I 72E+ 03 1.76E+ 03 1.808+ 03 1.868+ 03 1.928+ 03 1.988+ 03 2.06E+ 03 2.14E+ 03 2.22E+ 03 2 .32 E+ 03 2.42E+ 03 2.54E+ 03 2.67E+ 03 2.818+ 03 1.63E+ 03 1.68E+ 03 1.758+ 03 1.87E+ 03 2. 038 + 03 2.25E+ 03 2.548+ 03 2.9481- 03 3.498+ 03 4.24E+ 03 5 .30 E+ 03 6.84E-t. 03 9.15E+ 03 I 28E+04 1.88E+04 2.98E+04 5 .37 8+04 1.228+05 6.16E+01 I 50E+OI 6.43B+00 3. 42E+00 2.03E+00 1.28E+00 8 .39 E-01 5.5XE-01 3. 728-01... 20.595 30 .649 34 .475 17.144 11 .31 1 8 .35 0 6. 530 5.227 4 .34 3 3. 607 3. 002 2.489 2,045 1.6 53 1 .30 7 1.000 73I 500 3 10 ,162 34 .677 17.564 1 1.966 9.257 7.707 6.744 6.120 5.714 5.461 5 .32 0 5.269 5.291 5 .37 5 5.502 5.659 5.875 6. 233 7.020 ~ so 55 60 65 70 75 80 85 90 Torque (dim) ~ 25.157 25.246 25 .39 7 25.6 13 25.900 26.265 26.720 27.279 27.9 63 28.8 03 29.842 31 .144 32 .8 13 35.020 38 .078 42.625 50.248 66. 733 (table... Minimum 3. 0040 2.9990 3. 0070 Maximum 3. 0070 3. 0000 3. 0090 CB CP mils Preload M (dim) Brg Bore in Pad Bore in Journal OD mils 2.50 2.50 4.00 4.00 2.00 2.00 3. 50 3. 50 4.00 5 O O 4.00 5.00 3. 50 4.50 3. 50 4.50 0 .37 50 0.5000 0.0000 0.2000 0.4286 0.5556 0.0000 0.2222 3. 0040 3. 0040 3. 0070 3. 0070 3. 0040 3. 0040 3. 0070 3. 0070 3. 0070 3. 0090 3. 0070 3. 0090 3. 0070 3. 0090 3. 0070 3. 0098 2.9990 2.9990 2.9990 2.9990 3. 0000... 25 30 35 40 45 3. 96E+00 I 96E+00 1.27E+00 9.25E-01 7.09E-01 5.60E-01 4.49E-01 3. 628-0 1 2.92E-01 ?! .34 E-01 1.85E-01 1.44E-01 I 10E-01 8.04E-02 5.63E-02 3. 688-02 2.17E-02 1.08E-02 3 1 .35 2 15.657 10 .39 8 7.740 6.1 13 4.996 4.162 3. 5 03 2.956 2.486 2.072 I 70 1 1 .36 6 1.062 ,789 ,548 ,34 4 I 83 31.641 16.264 11 .35 5 9.084 7.889 7.254 6.964 6.918 7.072 7.409 7. 935 8.678 9.695 1 1.089 13. 046 15.901 20.595 30 .649... 90 Improving Machinery Reliability Table 3- 1 (continued) Bearing Coefficientsfor Tilting Pad Bearing Dimensional Tilting Pad Bearing Coefficients L = 1.875 in Load = 438 .0 Ibs ECC (dim) 05 IO I5 20 25 30 35 40 45 50 55 60 65 70 75 so 85 90 D = 4.500 in C = 00450 in = 2.50E - 06 REYNS Kxx (Ibh) 19748.2 9744.4 635 0.6 4611.7 35 35.0 2790.6 2 237 .0 1804.7 1455 .3 1166 .3 9 23. 9 719.1 546.0 400.7 280.4 1 83. 2... Bid Conditioning BID TABULATION FOR _ CENTRIFUGAL COMPRESSORS Vendor Item II 1 f 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 A - Description Compressor Model Type and S p l i t NO o f I m p e l l e r s T o t a l No o f I m p e l l e r s per Section Diameter... COllSlSterlL With s p e c i f i e d l i i d t e r l d l S ? Vendor r x p e r i e i i c e w i t h quoted n i d t e r i d l s ? 20) 21) 22 ) 23 24 25 ) 26 ) 27 78 29 30 31 ) 32 ) 33 34 35 36 37 3M 3Y 4u 41 42 43 44 45 4b 4n 49 50 51 52 53 54 55 56 57 I 58 1 59) 60 61 67 ) 63) b4 65 66 67 Sliould c r e d i t be given t u c a s t r t e e l c o n s t r u c t i o n ? Why i s Vendor (I o f f e r i n y PTFE-Coated... 107.9 53. 7 KYY (Ibhn.) cxx (Ib-s/in.) CYY (Ib-s/in.) HP loss (hP) 3. 058+06 1.528+06 1.01E+06 7. 538 +05 5.958+05 4.868+05 4.058+05 3. 418+05 2.88E+05 2.42E+05 2.02E+05 1.66E+05 1 .33 8+05 1.03E+05 7.688+04 5 .33 8+04 3. 358+04 1.788+04 3. 088+06 1.58Et-06 I.llE+06 8.848+05 7.688+05 7.068+05 6.78Et-05 6. 738 +05 6.88E+05 7.21E+05 7.7281-05 8.458+05 9.44E+05 1.08E+06 1.278+06 1.55Ec06 2.008+06 2.988+06 1.62E+ 03 1.64E-t- 03. .. 4280 NO Subcont Cormon Film 1 23 72 zoo0 Welded Own 220 130 0 Waukesha 851500 Centrif 2urnIG Yes Airfix Metrix None Later 3% Later 1nc 1uded None None Overseas Later Later Attached 80 Yes Yes Per Spec GWPJFSS 7a1.81 2.612.0 2 .31 1.86 P n R 638 0 CB-A is80 CH-B Ll2.9 1 138 0 CB-C M 13. 2 K12.8 Figure 2-16 Bid tabulation for centrifugal compressors 79 80 Improving Machinery Reliability CONSlDEKATlONS FUR... 128 13 12900 31 8 9911.9 83 16200 0 43 108 0-G3 680 A-I21 5-111 IMP-Y C l ALU-TEF 14000 6000 Yes Vendor Comnon Mec h Con t 62 None 2000 Riveted Michell 1821600 Self 1401180 Coalescer Bendix 31 6 Yes Seif Oynac None Attached 7% Later lnluded None None City J Attached Later 90 Yes Yes Per Spec FFCDAEA -821.91 2.711.9 2.612 .38 414 O(C) 8180 8589 870 914 6617121 530 12955 130 05 798 9791.972 18250 0-F4 1 23 0-G4 . 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53. 1 2 31 4) 5 6) 7) 8) 91 1u 111 12 I 13 14 15 161 171 181 19) 20) 21) 22 ) 23 24 25 ) 26 ) 27 78 29 30 31 ) 32 ) 33 34 35 36 37 3M 3Y 4u 41 42 43 44. Submitted Attached 88 8 - Y-101 Hor 7 hl 3 O(B1 8720 830 5 900 945 6847119807 128 13 12900 31 8 9911.9 83 16200 0 43 108 0-G3 680 A-I21 5-111 IMP-Y Cl ALU-TEF 14000 6000