Improving Machinery Reliability 3 Episode 2 ppsx

Requirements Specijication 19 WORKS LIST OF SPARES ORDER 352586 PAGE 5/ PROCESS GAS LOW SM NUMBER 1 set MACHINENO. LCTOl MANUFACTURED BY: HIROSHIMA WORKS - ERlAL NO. - 24 - 25 - 7” PARTICULARS 5th Stage Diaphragm and Nozzle 6th Stage Diaphragm and Nozzle d ATERIAL SLlS403 SC46 VORKINC NO. OF SUPPLY DRAW 4 :: 1 set 1 set 61962 41974 41963 Set ’ARTI NO. SKETCH SIN 66904425 zl E5- IEMARKl 7th St* g?F+ I CENTFR. FOR EXT. CONTROL VALVE EA Pl.hO. 1814-13 ACME RFG. CO ACNE NFG co 4814-13 LCT01 LCTOZ 90435-728 SPINDLE, REGULATING VALVE, PT. 4424-11 ST ~0386 DUG. 765-82245 FOR hCUE RFG. CO TURBINE ACME MFG. CO HEhkI IND. 4484-11 LClOl 90432-760 IIIBE, COCLING FOR GLlNO EONOCNSERS Pl FA N036C b DUG. ?64-10391 FOR ACRE HFG. f0 711RBINE ACNE MfG. CO HEAVY IND. 6 LCTOl 90437-763 TURN BUCKtE FOR GOVERNING LEVER fA PT.NO. 5841-47 hCME MFG. CO TURBINE ACME ttFt CO 5ac1-47 LCIO? vrroi 90432-7N TURN B‘JCKLE FOR GOVERNING LEVER PT.HO. EA 5843-32 RCHE MFO. CO TURBINE Figure 1-1 1. Spare parts cross-reference tables. 20 Improving Machinery Reliability (texr contiititedfroni page 15) 2.12.3 (Addition) Serial numbers shall also be cast-in or steel-stamped on the casing. The Pur- chase Order number and yard number shall be included on the equipment name- plates. Compressor nameplates shall include rated capacity and normal capacity. Here is another example: 4.3.3 Impeller Overspeed Test Each impeller shall be subjected to an overspeed test at not less than 115 per- cent of maximum continuous speed for a minimum duration of 1 minute. Impeller dimensions identified by the manufacturer as critical (such as bore, eye seal, and outside diameter) shall be measured before and after each overspeed test. All such measurements and the test speeds shall be recorded and submitted for the purchas- er’s review following the test. Any permanent deformation of the bore or other critical dimension outside drawing tolerances might be cause for rejection. 4.3.3 (Substitution) New impeller designs (without demonstrated operating experience) shall be subjected to an over-speed test of at least 120%. . . etc. After continuing to add to, delete from, or substitute for the various requirements spelled out in API 617, the specifying engineer must further define such items or design elements as instrumentation, valves, auxiliary piping, allowable sound inten- sity, etc. Unless supplementary specifications for these items are entirely relevant to centrifugal compressors, the specifying engineer should extract only those portions that actually apply to the compressor manufacturer’s scope of supply. Again: the specifying engineer should not resort to appending a series of general specifications from which the compressor manufacturer would have to pick an occasional applica- ble clause. Instead of developing the narrative specification document, some users assemble many general plant standards or plant specifications into a thick folder which then becomes the procurement specification for a centrifugal compressor. In other words, a general specification describing winterizing of all machinery, and specifications on “Flush Oil Injection for Rotating Machinery,” “Auxiliary Piping Fabrication and Installation,” “Pressure Instruments,” “Grouting,” etc. are all handed to the equip- ment vendor without first culling the relevant information from the extraneous, or inapplicable, data. Leaving it to the equipment vendor to find relevant clauses hidden in many separate documents puts a burden on the vendor’s personnel. Very often, this approach creates bulky specification packages that cause the vendor to add charges for potential oversights. In some cases vendors have refused to bid or have taken blanket exception to the entire specification by stating that their bid covers “Vendor’s Standard”-no more, no less. Although there may be occasions when Requirements SpeciJication 21 general “catch-all” specifications are appropriate, the user should apply these with discernment. By referring only to those paragraphs or clauses that really pertain to machinery and auxiliaries furnished by the vendor, the specifying engineer will reduce the probability of unexpected problems later in the job. Issuance of a perti- nent specification package leads to more accurate cost proposals, generally lower prices, and higher quality machinery. Considering Uprateability and Low Failure Risk An early decision to provide for future capacity increases or power output uprates may prove highly advantageous in plant debottlenecking or future expansion situa- tions. More often than not, the resulting pre-investment costs are surprisingly low, especially when unexpected mechanical reliability improvements result from the decision to pre-invest. A process gas compressor for a specialty chemical plant will serve as an example. This compressor required a throughput of 9500 cfm (16,140 m3/hr) to compress a medium molecular weight gas from about atmospheric pressure to approximately 120 pig (8.3 bar). The vendor’s initial offer was for a compressor with a maximum throughput capability of 11000 cfm (18,660 m3/hr). When encouraged to propose an alternative selection, the vendor submitted a marginally more expensive machine in the next larger casing size. Not only did this machine exhibit an uprate potential to 16000 cfm (27,180 m3/hr) but it proved mechanically superior, a true workhorse of a compressor which, a good 20 years later, had weathered more abuse than the plant manager cares to remember. The procurement of uprateable centrifugal compressors usually involves investigat- ing the feasibility of removing the last impeller and moving all preceding impellers into the location previously occupied by the next higher stage. Only a new first-stage impeller would have to be bought later. Figure 1-12 illustrates this principle. Another way of reducing the pre-investment cost difference would be to purchase the spare rotor (and one spare diaphragm and probably the coupling) to represent the most probable uprate case. An investigation of relevant process parameters would be required to determine whether the present plant requirements could be safely accom- Original 1 2 34 Upraled New 1 2 3 Figure 1-12. Compressor uprate through downward movement of stages. 22 Improving Machinery Reliability modated by the "uprate spare" if insertion of the spare rotor is required before actual plant expansion. In a similar vein, uprateability for reciprocating compressors might require pro- curement of stronger drive elements or a frame with blanked-off spaces for future connection of additional cylinders. Pumps would be purchased with one or more impeller locations "de-staged," Le., spaces left blank for future installation of addi- tional impellers. Steam turbines and large drive motors can be executed with through-shafts (double-ended shafts) for future addition of tandem drivers, etc. Typical questions to ask or to consider are: 1. Power capability-will the driver (electric motor, gear-speed increaser, steam turbine, or gas turbine) handle the uprate requirements? 2. Capacity-will the casing be rated for the anticipated uprate pressures and will equipment nozzles be sized to pass the flow? 3. Speed-can the machine handle the uprate speed without exceeding critical speed and tip-speed criteria invoked by API or self-imposed by qualified manu- facturers? Screening studies may be conducted with the assumption that machine input power requirements increase in direct proportion to increased mass flow rates. Addi- tionally, it is good engineering practice to add an overload contingency of roughly 10% to the uprate factor. Example: The uprate will be from a present 100 mass units per unit time to a future 130 mass units per unit time. The probable new power requirement will be 1.3 times the present requirement. The conservative approach would thus require driver sizing for (1.1) (1.3) = 1.43 times the present requirement. Capacity uprate capabilities must take into account not only the manufacturer's casing design pressure but also the pressure ratings or relief-valve settings of down- stream equipment. In the case of centrifugal compressor uprates, the desired uprate pressure ratio will result in a new polytropic head, H,. Using the symbol n to denote polytropic exponents, Z for the compressibility factor, R for gas constant, T for absolute suction temperature, and r, for compression ratio: H, = ZRT [n/(n - 1) [rp(n-')'" - I] This calculation is needed to determine later the approximate uprate speed. Uprate throughput limitations will usually be encountered if inlet nozzle velocities exceed 140 fps (42.6 m/sec) for air and lighter gases. For heavier-than-air-gases, maximum permissible inlet velocities may be significantly lower. Figure I- 13 gives a rule of thumb for permissible inlet velocities as a function of gas molecular weight and temperature. Approximate uprate speeds can be calculated with the help of the H, formula given earlier: N uprate = (N original) H, rerate / H, original Requirements Specificatiort 23 180 160 140 120 100 80 60 blw 20 30 50 70 100 Figure 1-13. Permissible inlet velocity as function of mole weight and gas temperature. The uprate speed thus calculated must not, however, exceed the mechanical limi- tations of impeller materials. This limit is typically reached at a peripheral speed of 950 fps (289 mhec). If N uprate would exceed this limitation, an additional impeller would have to be added. Centrifugal compressors can usually be built with a blank stage, Le., de-staged and ready to be modified at a later date. Specifying shaft dimensions, couplings, and thrust bearings for the uprate case will inevitably reduce the risk of machine distress and premature failure. In fairness, it must be said that these measures will result in marginally higher friction losses at thrust bearings and couplings, thus causing a slight increase in horsepower require- ments over base-case, normally sized machinery. The most effective way of reducing failure risk at the specification stage is to examine vendor experience. Detailed experience lists should be submitted for the purchaser's review. These lists must clearly identify the locations where identical compressor impellers, shaft stresses, couplings, impeller or turbine blade stresses, machinery bearings, bearing spans, speeds, etc. have been successfully used in the past. A detailed review of the vendor's claimed component experience should be made before issuing purchase orders, and this review should include telephone con- tact with other users. In some cases, a plant visit a continent away will be well worth it. We know of instances where, in preparation for the procurement of diesel genera- tors for South East Asia, the US-based review engineer visited an installation in West Africa, and where a U.S. manufacturer's steam-turbine experience was reviewed by a site visit to a location halfway around the globe. It was well worth it, in both cases. 24 Improving Machinery Reliability Auxiliary Systems for Turbomachinery: The Systematic Approach Malfunction of auxiliary systems (e.g., speed governors, lube and seal-oil supply consoles, etc.) is responsible for a large portion of unscheduled downtime for turbo- machinery. This is a fertile field for improvements in specifications, post-order relia- bility audits, pre-commissioning checkouts, and post-S/U maintenance. To ensure that the specification is written for maximum equipment reliability, the specifying engineer must generally go beyond the industry’s standard specification. He must know what it is he is specifying and how the system, subsystem, or even how a given component functions and performs. If he is not sufficiently qualified to make the decisions that necessarily lead to the procurement of highly reliable machinery, he should seek the advice of experienced plant engineers or consultants. While it is beyond the scope of this text to rewrite or pre-define entire specifica- tions for process plant machinery, it is important to make the preceding points as forcefully as possible. Using compressor lube and seal oil systems as an example, we want to see how the systematic examination of even a generally acceptable industry standard specification can lead to revisions and amendments that will make the equipment easier to operate and more maintainable, reliable, or accessible. Specifying Lube and Seal Oil Auxiliaries Lube oil or seal oil supply systems provide required quantities of lubricating or sealing oil to machinery bearings, gears, and/or seals. The oil has to be filtered, cooled (or preheated in some ambients), and pressurized. It has to be stored, purified, delivered, returned, metered, bypassed, degassed, switched through different head- ers, and blocked in. All of these functions require hardware, and while the purchaser may elect to leave the selection of hardware to the machinery manufacturer, the pur- chaser nevertheless must identify and specify the desired systems configuration. API Standard 614,* “Lubrication, Shaft-Sealing, and Control Oil Systems for Spe- cial-Purpose Applications,” can serve as a skeleton specification for lube and seal oil systems. However, to ensure reliable operation, a number of supplementary require- ments should be specified by the purchaser. Referring to Figure 1-14, we would add to or modify the reservoir as follows: The filter-breather should be extended 6 or more feet (2 m) above the reservoir top to encourage oil vapors to condense inside the extension piece rather than escaping to the atmosphere. Furthermore, during periods of gas leakage past the compressor seals, we want the gas to escape well above grade. For better heat transfer and reduced corrosion risk, the steam-heater cavity at the reservoir bottom should be filled with a heat-transfer oil or perhaps discarded lube oil. A filler standpipe and breather cap should be provided. ___. ._____ - “API Standard 614, “Lubrication, Shaft-Sealing, and Control Oil Systems for Special-Purpose Applications,” Third Edition, 1992, repiinled by courtesy of the American Petroleum Institute. Requirements Specification 25 I SLOPED DEGASIFICATION TRAY MAXIMUM OPERATING LEVEL 9 ELECTRIC 5- SUPPLY PUMP SUCTION CONNECTIONS TWO TAPPED GROUNDING PADS (SEE NOTE 61 I ALTERNATIVE ARRANGEMENT [SEE NOTE It) - PLUGGED PURGE CONNECTION FILTER-BREATHER CAP (SEE NOTE 9) EN1 CONNECT10 LIEF VALVE, CONTROL VAL NDITIONER. AND OTHER ED OIL RETURNS SPARE PLUGGED CONNECT1 PENING WITH STRAINER DUAL NONPRESSURIZED EXTERNAL-TYPE FLOAT (SEE NOTES 121 STILLING TUBE AND STATIC EOUALIZER SIPHON BREAKER STEAM HEATER (SEE NOTE 31 BLIND-FLANGED DRAIN CONNECTION \ 'BAFFLE ATTAChED TO ST.LLlhG TLBES AND PRESSURiZED O.L RETURhS TO PREVEhT STlflR NG OF BOTTOM SEO.MENTS [SEE NOTE 61 NOTES: I Option A-22a: The purchaser may spcciiy a particular oil condi. !loner and other pressurized oil returns in addition IO the spare top connection. 2 Option A.22b. The purchaser may speciiy an electric healer. 3 Opiton A-22c: The purchaser may specify a steam heater. 4. Option A-22d: The purchaser may specify an oil conditioner WE- lion connection. 5. Option A-22e. The purchaser may specify P siphon breaker when an oil condilioner suction conneclion is spccificd. 6. Option A-22f: When specified. lwo lapped grounding pads posi. rioned diagonally to each oiher shall be provided. 7 A blind flange shall be provided lor venling the reservoir. Far seal-oil resewoirs, this vent shall be piped to a sale localion by Ihe purchaser. 8. Individual oil relurns shall be located away from the pump suchon and arranged 10 provide the maximum residence lime 9. A filtcr.bredlhcr capis no1 permitied on B reservuir contdning 5rdl ail. IO. Purge and vcnl connections shall enter Ihe lop ')I the iexrroii No exlension tubcr or seals are pcrmitlcd. II. For nonpresrurired gravbly oil return liner. a rlilltng tube or rlopcd degasilkation my arranged IO prcvenl splashing and provide free relcaic of luam and gar is required for cvcry return inlet and spare connection. 12. An internal-lype nodl shall be protected by a siatic-cvnducling shield. Figure 1-14. Oil reservoir, standard arrangement. (Courtesy American Petroleum Insti- tute.) If an electric heater is used, it should be located in the steam-heater cavity at the reservoir bottom, as long as the cavity is filled with heat-transfer oil or discarded lube oil. This will reduce the risk of lube oil deterioration from prolonged contact with an excessively hot heater cartridge. 26 hnprovirig Mcrchinery Reliability RETURN LINES TO RESERVOIR MAIN STANDBY EMERGENCY PUMP PUMP 4 4 4 f 4c-W AUXILIARY PUMP SUCTION (SEE NOTES 7 AND 8) (TYPICAL: SEE NOTE 4) (SEE NOTE 5) - PUMP SUCTION $71 FROM RESERVOIR NOTES: 1. Option A-20a: Alarm switches arcomitled if(a) the running signal is taken from the molorslarlcr or (b) an alarm swilclt is on the turbine driver. pumps. 2. Oplion A-20b The purchaser may specify a bypass valve to ~1~1. 3. Oplian A.2Oc: The purchaser may rpecily an emergency pump. 4. Oplion A-2Od: Far psilive displacement pumps. the purchaser may specify an auxiliary emergency suclion line from the reservoir 10 the main, standby. or emergency pump. 5. Suclion V~~YCI are omitted for pumps submerged in the rc6crvotc. 6. The pressure-regulating (relic0 valve is omitled lor centrilugal 7. For centrifugal pumps., Ihe line slrainers are omillcd and iempo. rary screen8 are provided. 8. A basket-type screen shall be used instead 01 a lint slramer for the suction of pumps submcrged in the reservoir. Figure 1-15. Primary pump arrangement, centrifugal or positive displacement pumps. (Courtesy American Petroleum Institute.) In Figure 1 - 15, primary pump arrangements (positive displacement pumps): Valved vents at high points should be required. This may be impractical, yet provi- sion is required to prevent standby equipment from becoming vapor bound. Drilling a small hole into each discharge check-valve flapper will serve the same purpose. The main pump should preferably be steam-turbine driven. Motor-driven standby pumps will start faster and more reliably. Motor-driven spare and emergency pumps should be powered by separate feeders. Figure 1-16 represents typical twin coolers and filters having the same continuous flow transfer valve. Note that in all but the most elementary cooler arrangements, Requirernents Specificcitiori 27 OIL OUT x FILTER [SEE NOTE 3) \E FILTER 0 , [SEE NOTES 1 AND 2) +q-i?TJ NORMALLY OPEN - OIL IN NOTES: 1. Option A-l8a: The purchaser may specify a bypass oil line and a constant-temperature control valve. 2. Option A-18b: It the iaildosed (FC) feature oi the direct-acting temperature control valve is not acceptable. the purchasea may specify a valve with a iail-locked (FL) feature. 3. Option A-18c: The purchaser may specify a high-temperature switch (TSH) and/or a low-temperature switch (TSL). 4. Option A-l8d: The purchaser may specify light shutoff requiring spectacle blinds. Figure 1-16. Twin oil coolers and filters with a single continuous flow transfer valve. (Courtesy American Petroleum Institute.) 28 Improving Machinery Reliability U bypass oil lines and constant temperature control valves should be specified. Also, venting of filters and coolers to safe areas must be considered. Figure 1-17 depicts a direct-contact-type accumulator. Allowing a trickle of oil to leave through an orificed bypass near the accumulator drain and returning this oil to FC 1 (SEE NOTE 3) 011 JT r I AS T CHARGE (SEE NOTE 2) ALARM ACCUMULATOR TANK DRAIN [...]... restating the original equipment manufacturer’s recommended lubricants to an intelligent consolidation of .NOllVlN3Wfl30a S1YWd PYVdS AN3NIH3WW UOWW 48 Improving Machinery Reliability 7th S T R E E T E A S T - / 7 BLOCK 7 AREA 0 0P - 6 A 0 -68 P 0 - W 3 W 4 > I3 m E L 3 P-17A Figure 1 -33 Equipment lubrication plot plan P-178 EQUIPMEN1 L U B R l C A l I O N SUMMARY I LOCATION OATA/ LUBRICATION DATA... M i s t GG = Grease Gun GC = Grease C e n t r a l BO = B o t t l e O i l e r C I = C i r c u l a t i n g System UX -2 = UNIREX -2 T - 32 = T e r e s s t i c - 3 2 G-90 = Gear O i l - 9 0 SY - 32 = Synesstic - 32 Figure 1 -34 Equipment lubrication summary Requirements Specijkntion 49 Figure 1 -35 .Oil-mist lubrication summary installation Completeness Checklists Rotating equipment has to be thoroughly checked... Reciprocating Compressors 7400 (2 machines running) k$ I384 139 0 11888 920 0 k5760 404 14904 24 64 - I5 82 - 4440 Included/NA 400 - k 520 .5 14 400 k$19,5 02 Maintenance: See Table 1 -3 or use plant data New Total to the plant's technical staff in advance of plant startup Machinery data and documentation packages often arrive too late to contribute to a successful plant startup Machinery then has to be commissioned,... 1 0 1 5 Rev./Oate 0 :3- 2- 79 Reference Stdnddrd: P l a n t Spec Exclusions: 18 -3. 2 P -20 2 P - 3 2 3 The i l l u s t r a t i o n s used i n t h i s s e c t i o n cover b e a r i n g arrangement and l u b r i c a t f o n f o r F l e c t r i c motors, b u t t h e b e a r i n g types and p r i n c i p l e s a p p l y t o a l l o i l o r grease l u h r i i a t r d bearings LUBRICATION I 2 Wet O i l Sump o r... cation 33 (SEE NOTE 1) (SEE NOTE 2) TYPICAL ARRANGEMENT FOR MECHANICAL-FLOAT-TYPETRAPS E~&~l\:NopRoTYPICAL ARRANGEMENT FOR T' LEVEL-TRANSMITTER-CONTROLLER-TYPE TRAPS NOTES: 1 Option A-12a: The purchaser may specify a vent to the flare 2 Option A-12b: The purchaser may specify a vent to the gas system 3 Option A-12c: The purchaser may specify a vent to the suction of a lower pressure casing 4 Option A-12d:... costs studies Specifying Machinery Documentation Requirements Safe operation, proper surveillance, and cost-optimized maintenance of machinery requires that a good deal of machinery- related data be available and made accessible 38 Improving Machinery Reliability Table 1 -2 C o s t Analysis for Compression Systems Motor-Driven Centrifugal Horsepower input Piping system Foundation 3- year cost of power Barrel... ) an orifice, ( 2 ) check valve, and (3) rapid fill valve During normal operation of the machinery unit, a trickle of lube oil flows through the orifice into the tank, and returns through a topmounted nozzle back to the reservoir When the static pressure in the elevated tank exceeds the pressure in (4) the supply header, lube oil flows down through the check 32 Improving Machinery Reliability I G A... function of machinery components and interacting auxiliary systems before he can specify for reliability, maintainability, and efficiency To close the loop, we include Figure 1 -24 , a simplified lube and seal oil schematic for a turbine-driven centrifugal compressor 34 bnproving Machinery Reliability I Figure 1- 23 Overhead lube-oil rundown tanks (Courtesy of The Elliott Company, Jeannette, Pennsylvania.)... LATCHING AND STARTUP INSTRUCTIONS 42 Improving Machinery Reliability Figure 1 -27 Machinery vibration spectrum analysis data 5 Tabulation of minimum number of parts to be kept on hand by storehouse or local vendor 6 Performance curve, if applicable 7 Mechanical seal and seal-gland drawings, if applicable 8 Design-change data A typical design-change form is shown in Figure 1 -28 It is used to document one... bolts are tightened Only then can the attaching bolts be tightened (36 ) Inspection before assembling the governor-aide bearing After cleaning the upper bearing housing, the bearing liner la fitted, and plastigage placed on the bearing liner 2 1bS) FILE REFERENCE OAT€ 5/9/80 3 IbZ) MACHINERY RELIABILITY PROGRAM M-80.4-C2Ol Figure 1 -31 Reassembly procedures for major HP steam turbines Illustrated instructions . be safely accom- Original 1 2 34 Upraled New 1 2 3 Figure 1- 12. Compressor uprate through downward movement of stages. 22 Improving Machinery Reliability modated by the "uprate. LCIO? vrroi 90 4 32 -7N TURN B‘JCKLE FOR GOVERNING LEVER PT.HO. EA 58 43- 32 RCHE MFO. CO TURBINE Figure 1-1 1. Spare parts cross-reference tables. 20 Improving Machinery Reliability. CONTROL VALVE EA Pl.hO. 1814- 13 ACME RFG. CO ACNE NFG co 4814- 13 LCT01 LCTOZ 90 435 - 728 SPINDLE, REGULATING VALVE, PT. 4 424 -11 ST ~ 038 6 DUG. 765- 822 45 FOR hCUE RFG. CO TURBINE