Marine vol 1 part 8

MARINE ENGINEERING PRACTICE Volume I Part MARINE STEAM TURBINES by R COATS, C.Eng., F.I.Mar.E., M.I.Mech.E., M.R.I.N.A., M.I.Weld., M.N.E.C.I.E.S THE INSTITUTE OF MARINE ENGINEERS CONTENTS Page Introduction I Evolutionary Changes and Background The Modern Turbine Cleanliness of the Machinery and its Connecting Pipework Avoidance of Contamination of the Working Fluids Operating Procedures Operating Troubles Maintenance and Adjustment Papers for Further Study References 57 58 63 78 82 96 103 INTRODUCTION This Part is an attempt to review a wide range of marine turbine machinery Of necessity, many interesting designs have had to be omitted It has not been thought necessary to delve too deeply into the past, as the old designs have already been adequately covered.· Many turbines of these older types are still undoubtedly in good service, but, in the main, the illustrations in the present work will show more recent designs It is hoped that the student or the operator of the older type of machinery will refer to the earlier book· for relevant information It is hoped that the ground covered, and particularly the section on the operating aspects of the machinery will be of real practical value, and that the supplementary information given in the abstracts from important papers on steam turbine machinery will provide a good stimulus for further study • "The Running and Maintenance of Marine Steam Turbines." In "The Running and Maintenance of Marine Machinery," Fifth Edition Marine Media Management Ltd., London 1 EVOLUTIONARY CHANGES AND GENERAL BACKGROUND The evolution of the marine steam turbine over the last twenty years has brought about significant changes, not only in physical appearance, but also in ratio of power to weight, in steam inlet conditions, in efficiency and fuel consumption, in reliability, in the change from manual to remote control, and, very significantly, in the time taken to reach full operating power after starting from cold conditions In general, the principles governing the correct maintenance and operation of the machinery are unchanged, with differences in emphasis and time scale arising from increased knowledge and differences in detail designs These principles are: 1) Cleanliness of the machinery and its connecting pipework; 2) Avoidance of contamination of the working fluids, namely water, steam, fuel and lubricating oil; 3) Adherence to makers' recommendations on type of lubricating oil for initial fill and make-up purposes, and attention to fine filtering and water removal; 4) Orderly procedures for warming through, start-up, manoeuvring, full away and closing down to avoid distortion; 5) Attention to drainage facilities during critical periods to avoid carryover of water into the turbines; 6) Avoidance of rust or other corrosion-promoting conditions; 7) Orderly recording and analysis of instrument readings in comparison with trials figures; check on power and fuel consumption; 8) Attention to auxiliary machinery to ensure correct movement of fluids to and from the engine; 9) Attention to boiler cleanliness and efficient combustion to ensure optimum overall efficiency and minimum fuel rate; 10) Where automatic controls are incorporated, periodic attention and servicing to ensure reliable operation It is important to consider these points in more detail, but before doing so, it is necessary to review th,' nasic design principles and illustrate the present state of the art 2 THE MODERN 2.1 GENERAL TURBINE ASPECTS The design of the marine turbine over the past twenty years has been greatly influenced by economic and competitive factors, requiring reduced fuel consumption, smaller weight to power ratio, higher steam pressures and temperatures, higher rotational speeds and higher peripheral speeds Improvements in blade and nozzle have been made by application of aerodynamic theory and vast amounts of wind tunnel research have advanced the efficiency of impulse turbines to such an extent that the high pressure portion of a machine is almost always of the impulse type The reaction stages are confined to the low pressure end of the machine The boundary between impulse and reaction stages is somewhat blurred nowadays because most impulse blades operate with some degree of reaction, and many reaction stages are made of disc and diaphragm type of construction and look like impulse stages There are exceptions, however, such as the Westinghouse design and the Blohm and Voss design The major influences on the impulse design have been the higher steam conditions and the importance of reducing leakage effects, and the reduction in axial length arising from impulse construction The most popular designs of turbine in present construction are the StalLaval, General Electric, Mitsubishi and Kawasaki types The only active British design at the moment is the GEe (formerly AEI/English Electric) type There are, of course, many British and foreign flag ships still sailing with Pametrada turbines Several striking features will be evident in modern turbines when compared with those in "Running and Maintenance of Marine Machinery" There is the more general use of high pressures and temperatures, e.g Manufacturer Stal-Laval General Electric General Electric Reheat Pametrada I.H.I Standard Inlet Conditions 62 bar/51Ooe (900 Ib/in2 g/950°F) 59 bar/510oe (850 Ib/in2 g/950°F) 100 bar/510oe (1450 Ib/in2 g/950°F/950°F) 59 bar/510oe (850 Ib/in2 g,950°F) Reheat 86 bar, 513°Cj51Ooe MARINE ENGINEERING PRACTICE Several firms have standard reheat designs introduced after Pametrada had publicized their "1000/1000/1000" design The main difference was that Pametrada proposed a three cylinder high pressure/intermediate pressure/low pressure (H.P./I.P./L.P.) scheme, whereas General Electric and Stal-Laval used a two cylinder scheme, with H.P and J.P sections on the same rotor In addition, there are many improvements in details, such as flexible couplings, bearings, casing construction, bearing supports, and greater use of fabrication and there is the ',vf'rall aflrl""~eral use of impulse type construction 2.2 TURBINE AND GEARING ARRANGEMENTS Apart from differences in detail, there are noteworthy differences in arrangements of gearing and condenser machinery It has become fashionable to adopt the so-called "single plane" arrangement in which all bearing centre lines lie in the same horizontal plane In the Stal-Laval arrangement (Fig 1) (Ref 1), use is made of a mixture of epicyclic and parallel shaft gears The H.P turbine may have a star gear first reduction, with a planetary epicyclic second reduction, arranged forward and aft, respectively, of the final reduction pinion which engages with the main wheel The L.P turbine has a planetary epicyclic first reduction gear arranged aft of the final reduction pinion The principal change which allows the single plane design to be achieved is the axially directed exhaust, forward from the L.P turbine, direct into the side of the main condenser arranged athwartships The exhaust duct surrounds the forward turbine bearing, to which access has to be obtained via a vertical shaftway This is not a very attractive feature, but has not been known to lead to any operating difficulties The ahead exhaust stream passes over the astern casing on its way to the condenser The astern exhaust faces the same way, thus removing any possibility of the astern steam affecting the ahead blading (Fig 2) The main attraction claimed for the arrangement is the low headroom needed for its accommodation, which permits the boiler to be arranged over the turbines, thus leading to a short engine room space (Fig 3) It will be clear that there is a power limit to the axial exhaust single flow arrangement, which has not yet been reached at 29828 kW (40000 shp) in the Stal-Laval design Eventually a double flow exhaust will be needed, with downward flow to an underslung condenser, for higher powers It is of interest, however, that Jung (Ref 2) claims that a power of 93000 shp is possible with reheat using only one flow General Electric's MST 13 standard (Figs and 5) (Ref 3) is similar in several respects to the Stal-Laval arrangement It is of the single plane type with the L.P turbine exhausting axially to :: >'ld:ate condenser Access to the forward bearing is via a vertical space between the two halves of the THE MODERN TURBINE MARINE ENGINEERING PRACTICE enveloping turbine exhaust The major difference is in the type of gearing, which is entirely par::lllel shaft type For claimed economy of manufacture, the primary and secondary gearboxes are separate from each other The higher powered MST 14 standard shown in Fig (Ref 4) reverts to orthodox dual tandem construction for the gearing, and has the advantage of sharing the power amongst four pinions in the final reduction This leads to a smaller diameter for pinions and wheels than is general for the Stal-Laval standard The L.P turbine retains the axial exhaust The even higher powered MST 19 standard range covers powers from 33556 kW-89 484 kW (45000-120000 shp) with a selection from two H.P turbines and three L.P turbines in both non-reheat and reheat forms It is of interest to note that all of these have dual tandem gears and that the L.P turbines exhaust downwards into underslung condensers The Pametrada standards (Refs and 6) retained the orthodox arrangement of gearing, with dual tandem above 18643 kW (25000 shp), and in all cases have the L.P turbine exhausting downwards into an underslung FIG 3.-Stal-Laval advanced propulsion machinery in a tanker condenser (Figs and 8) (Ref 6) The major overall dimensions and weights for this standard series are given in Tables I and II of Ref Figure shows a 14914 kW (20000 shp) set of machinery from the standard range-later installed in s.s British Cmifidence-erected on the test stand at John Brown Engineering Figure 10 shows a 19760 kW (26 500 shp) set with dual tandem gearing in s.s Ottawa Figure 11shows the Pametrada Prototype machinery on the test bed at Wallsend Research Station This operated at 55 bar (800 Ib/in2 g) and 557°C (1035°F) and completed an extensive series of trials in 1963 Figures 12 and 13 show the H.P turbine from this set MARINE ESGIN' ~:RING PRACTICE In the designs with single casing L.P turbines, a bypass pipe is provided to lead the exhaust from the H.P turbine to the condenser A blanking plate has to be fitted over the L.P inlet In double casing L.P turbines, a different arrangement is possible and the drawings should be referred to The appropriate orifice must be fitted in the H.P ahead exhaust line and similar arrangements are made for the H.P astern exhaust, with its orifice in place If the H.P turbine is taken out of service, the flexible coupling should be disconnected, the steam supply to and exhaust from H.P ahead and astern turbines blanked off, and the restriction orifices fitted at the inlet end of the L.P emergency steam supply pipes The water spray fittings should be connected up for the L.P ahead turbine When either turbine is taken out of service, the gland steam connexions must also be blanked off 7.10 GEARING MAINTENANCE Caution: Oil vapour is present at all times in the gear cases, and every precaution against explosion should accordingly be taken whenever work is done on or around the gear units 7.10.1 Introduction The gear teeth should be inspected at regular and frequent intervals through the handholes in the casing, taking great care that only one handhole 92 MARINE ENGINEERING PRACTICE be open at a given time and this be closed as soon as possible and before the next is opened Burred or roughened tooth surfaces may be honed but this should only be done under expert supervision It is important that gearing should be given a running-in period in service before full load is applied, both when gearing is new and after any work has been done on the teeth The duration of this period should, within reason, be as long as possible, and no severe manoeuvring be carried out during it The flexible couplings should be examined at least four times a year and cleaned as necessary, since accumulated sludge will seriously impair their flexibility and their lubrication (This does not apply to diaphragm type couplings, which are sometimes fitted.) The oil sprays should be inspected regularly and the spray nozzles should be cleaned at the slightest evidence of obstruction The importance of keeping these nozzles open cannot be emphasized too strongly 7.10.2 Dismantling of Gearing Caution: The propeller shafting must be locked rigidly before any bearing of the reduction gear is opened up Extreme care should be exercised in the dismantling operations to avoid bruising or otherwise marring the finely finished surfaces of the gear teeth, journals and bearings Slings should be well padded with thick cloth When the casings are open care should be taken to keep out dirt and other foreign substances Lifting gear supplied by the manufacturers should be used The dummy bearings for use in supporting the rotors when the journal bearings are out should be sild into p;acc und':;i WtO ~n •/t juurnals as the lower halves of the bearings are slid out, and they should be well oiled before they are used in order to guard against scoring of the shaft journals The thrust bearings can be completely dismantled without the need for disturbing any part of the gear assembly other than the bearing housings and the bearing itself 7.10.3 Re-assembly of Gearing Before commencing re-assembly, it should be definitely ascertained that the interiors of the casings are clean, that all tools or other foreign objects which may have found their way into the casing have been removed The gears, bearings and other parts should be inspected carefully, cleaned and painted with marking as described below before they are re-assembled, and the metalled surfaces of the bearings should be well oiled MAINTENANCE AND ADJUSTMENT 93 of the gears before the gears are run The marking should be of oilproof type and not transfer marking, e.g Tudor Blue is suitable In addition to providing evidence of the meshing accuracy on first installation this permanent marking provides a ready means of observing that no misalignment has arisen due to gear case distortion, bearing wear, etc in subsequent operation A permanent record can be retained for future reference by uplifting the marking by means of transparent adhesive tape and transferring it to plain white paper 7.11 LUBRICATION The life and reliability of the installation depends on good lubrication The oil pressure at the bearings should be not less than 0·7 bar (to lbjin2) The oil temperature should be from 46-49°C (115 to 120°F) at inlet to the bearings, sprayers, etc If it is too low, the temperature in the drain tank will also be too low, and any water which may have entered the lubricating system will not be precipitated If it is too high, the life of the oil may be shortened by excessive oxidation The temperature of oil leaving the bearings should not normally exceed 89°C (180°F), but it should be emphasized that the bearing white metal surface shells themselves may be at a considerably higher temperature with safety Water carried in suspension in the oil causes corrosion offerrous parts such as bearing journals and gear teeth, and also lowers th~ lubricating value of the oil Salt water emulsifies fairly readily with lubricating oil Fresh water is more easy to separate from oil Care must therefore be taken that no salt water enters the oil via leaks in the oil coolers In operation the oil pressure will normally be higher than the sea water pressure and the tendency will be for oil to be lost to the sea; but when shut down, the reverse will take place and dangerous quantities of salt water may enter the lubricating system As a precautionary measure, the water in the oil cooler should be drained if the machinery is idle for a long period, and the drain cocks should be left open To check for leaks the oil pump should be started with the oil cooler in this condition Should leaks be present, oil will drip from the drain cocks Any such leak should be remedied immediately Other means by which water may enter the oil are leakage of steam from glands into bearings (which ought to be eliminated by the proper use of the glands condenser) and inevitable condensation from the atmosphere The oil treatment plant and purifiers provided will largely eliminate the accumulation of significant amounts of water and sludge in the system Any deficiency of oil due to evaporation and leakage should be made up from a clean oil storage tank Full flow filters should be checked daily, and the elements replaced whenever the pressure drop exceeds the limiting figure Attention should be paid to the nature of the dirt filtered out 'is this may be the first clue to developing trouble 94 MARINE ENGINEERING PRACTICE The physical properties of a typical oil suitable for the turbines and gears of a marine installation are given below Viscosity Specific Gravity Viscosity Index Pour Point Flash Point Demulsification No Miscellaneous tests Inorganic acidity Organic acidity (max.) 7.12 CONDENSER 82-92 cSt at 38°C (lOO°F) 8·2 cSt (min.) at 99°C (210°F) 0·88 to 0·92 50 (min.) - 7°C ( + 20°F)(max.) 166°C (330°F)(min.) 300 (max.) The oil must show no corrosion in a copper strip test, must pass a foaming test, a 48 hour salt water corrosion test at 60°C (140°F) on steel after washing the oil with water, and an oxidation test Nil 0·20 mg/g KOH MAINTENANCE AND DEFECTS The most important defects in the machinery operation which can be attributed to the condenser are, sudden and serious loss of vacuum, a gradual but slight deterioration in vacuum and an increase in feed water salinity 7.12.1 Sudden Loss of Vacuum This will most probably ar i:;e from the incidence of an air leakage, but could also be due to a rapid, though unlikely, reduction in the cooling water rate or to deterioration in air ejector performance Sources of leakage which should be investigated are the small bore piping connexions between the condenser and the kenotometer and defects in any of the joints on the pads and flanges mounted on the condenser casing a) Cooling Water Circulation Failure of the pump or even uncontrolled partial reduction in the cooling water flow rate is not considered a normal hazard but blockage has been known to occur due to weeds or polythene sheeting Vacuum will deteriorate rapidly if the flow rate is not maintained and this condition may normally be detected by a substantial increase in the cooling water temperature rise across the condenser In systems where, under steady operating conditions, the cooling water rate is automatically controlled to maintain the vacuum at a predetermined value, any sudden failure or involuntary reduction of sea water circulation will be recorded by alarm signal b) Air Ejector Failure of the air ejector will most likely be due to reduction in the flow of driving steam to th,~ejt ·:lor nozzles '"nce efficient perform- MAINTENANCE AND ADJUSTMENT 95 ance of an air ejector is inherently somewhat critical for a particular design duty, partial blockage of the nozzles due to small flakes of scale or other material can curtail performance sufficiently to result in serious loss of vacuum 7.12.2 Gradual Deterioration of Vacuum Gradual, though slight deterioration of vacuum over a relatively long period, is almost certainly due to reduction of the heat transfer rate between the cooling water and the tubes This arises from a slow build up of deposits which foul the inside tube surface The rate of fouling will mainly depend on the sea trade route If such condition is suspected, the tubes may be brushed using nylon bristles The frequency at which attention is given must be largely governed by experience 7.12.3 Salinity of Feed Water If the degree of feed water salinity exceeds the permissible amount, a leakage of sea water into the steam side of the condenser may be suspected Leakage can occur due to tube rupture caused by erosion and by failure of tube end packing rings if fitted Tube erosion is usually most severe near to the water entry end of the tube, but may not be easily detected without water test Tubes which are known to be damaged may be temporarily plugged, pending replacement at the earliest opportunity 7.12.4 Additional Inspection and Maintenance In addition to the foregoing possible defects arising during service, routine inspection inside the water boxes should be carried out by examination of the tube plate for signs of tube or tube packing failure and erosion pitting of the tube plate surface One should also examine the mild steel anti-corrosion plates In the case of fabricated mild steel water boxes, which are protected by rubber lining, an excessive rate of wastage may be due to a defect in the rubber lining The plates should be cleaned of corrosion products and organic growth every to months They should be replaced if they reduce to 50 per cent of the original size The rubber lining of the water boxes and doors should be checked to ensure that it-shows no signs of having "lifted off" the parent metal and that it has not ruptured Any such defects should be rectified at the earliest opportunity The same remarks apply to epoxy coatings Remove sludge accumulation from water boxes 7.12.5 Ferrous Sulphate Protection The beneficial effect of the anti-corrosion plates is increased by dosing the cooling water with ferrous sulphate (5 ppm equivalent to 4·5 kg (101b) per 909 200 I (200 000 gal of cooling water) injected as a solution under minimum flow conditions, for one hour, once per week (Ref 26) PAPERS FOR FURTHER STUDY 8.1 ADVANCES IN STEAM TURBINES FOR MARINE PROPULSION A D Somes (General Electric Co.) (Ref 10) This paper considers advances in the design and construction of steam turbines up to 1959, and is of particular interest because it gives information on what was then a new philosophy on rotor critical speeds for marine applications 8.2 THE INFLUENCE OF THERMAL EFFECTS ON THE MANOEUVRABILITY OF MARINE TURBINE MACHINERY B J Terrell (Pametrada) (Ref 20) This paper discusses the peculiar requirements of marine turbine machinery during manoeuvring, when changes of temperature raise problems It records some of the fundamental thinking which tried to quantify the thermal effects (such as differential expansion and distortion) and the stresses induced during the warming through process The theoretical figures are substantiated by test results There is a good discussion with further useful information 8.3 MARINE STEAM TURBINE DESIGN AND OPERATION A F Veitch (Pametrada) (Ref 22) The first part of this paper is concerned with the design aspects of marine turbines, and recounts some of the dilemmas facing the turbine designer and reasons for their particular solutions It compares earlier Pametrada designs (1952) with later higher temperature designs (1960), and gives details of the Prototype I machinery which operated at 55 bar (800 Ib/in2 g) and 557°C (1035°F) It then gives advice on operation- of marine turbines There is an interesting discussion PAPERS FOR FURTHER STUDY 97 Llangorse turbines Trials of hydraulic transmission and boiler commissioning trials are also described and the paper concludes with the trials of machinery for the British Bombardier In each case, the requirements of the trials, some of the findings and the developments of special instruments are described Arising from this, general findings are given as to warming through and control of turbine machinery during rapid transient conditions caused by manoeuvring requirements This paper is full of useful information and also has a useful discussion 8.5 PAMETRADA STANDARD TURBINES, PRESENT POSITION AND FUTURE OUTLOOK R Coats (Pametrada) (Ref 6) This paper by the present author describes what at that time was the recently introduced Standard Range of Pametrada turbine machinery Many of the illustrations are included in this Part and show soundly based designs now in successful service It records that 447 ships having Pametrada machinery totalling 594470 kW (7 100000 shp) had gone into service since 1944 The paper includes information on measured steam rate from test bed trials, the effect of using a vacuum higher than design, and gains from using reheat There is a most useful and informative discussion 8.6 30000 SHP UNITIZED REHEAT STEAM TURBINE PROPULSION T B Hutchison (Esso Petroleum) (Ref 33) Drawing attention to the increasing size and power demand of tankers, this paper compares the thermal efficiency then achievable in power station machinery with the lower values achieved in marine applications It propounds that "unitized" design of the complete power plant is the right way to achieve better efficiency and greater reliability The author's definition of unitization is "the optimization of requirement, the design of equipment to meet that requirement and the full and exclusive employment of the equipment for the single purpose intended" The paper also draws attention to the gains to be expected from using low speed, large diameter propellers, the use of scoop circulation for the main condenser, and gains to be expected from even higher steam inlet and reheat conditions It is a well presented and useful paper, supported by operational and research experience, and every junior engineer would derive great benefit from reading it 8.7 MATERIALS FOR ADVANCED STEAM CONDITIONS AND THEIR INFLUENCE ON OPERATION OF MARINE TURBINE AND BOILERS H E C Hims and S H Frederick (Pametrada) (Ref 34) The first half of this paper discusses the metallurgical problems associated with the selection of materials and their fabrication in manufacture The second half is devoted to the effects of such materials on operation, covering most points between the first admission of steam to an installation 98 MARINE ENGINEERING PRACTICE and the end of the cooling down period after operation Both parts contain most useful background information-including sections on distortion and on cylinder joint bolt tightening-up stresses-which every operating engineer would find most useful 8.8 Northern Star: EVOLUTION AND OPERATION G S Jackson and C Winyard (Shaw Savill) (Ref 7) This paper is a description of the evolution of a high class passenger liner, its machinery and equipment, and its service operation during its first five round-the-world voyages A detailed description of the main turbine propulsion machinery is given, together with details of the heat balance diagram, closed feed system, electrical installation, lighting system and air conditioning machinery The operational part of the paper gives detailed information on the unfortunate H.P turbine thrust failures which occurred on two separate occasions The investigations and remedial measures taken make very interesting reading The failures were shown to be part of a pattern which afflicted the marine industry at about this time These proved to be due mainly to the growing use of oils containing extreme pressure additives, some of which were not compatible with the thrust collar and pad materials under adverse conditions, e.g the presence of a foreign particle between the working surfaces The discussion to this paper really started the public debate on this machining type thrust failure 8.9 MARINE TURBINE THRUSTS R Coats (Pametrada) (Ref 14) This paper records the case histories of ten engines affected by severe thrust collar wear (one of which was of the Northern Star mentioned above), reviews the general design aspects of the problem, and discusses the influence of types of oil and cleanliness of oil systems It discusses the possibility of cavitation being the common link connecting the troubles, associated in some way with the more general use of extreme pressure oils It concludes that the most important factor leading to the severe form of damage illustrated is the use of extreme pressure oils, associated with cavitation arising from turbulence due to the presence of dirt, inadequate oil supply pressure or local reduction in oil pressure due to the complex flow conditions within the block The paper is well illustrated with examples of the type of failure and there is an excellent discussion 8.10 ENGINEERING TESTS FOR MARINE TURBINE LUBRICATING OILS R F Darling and T Isherwood (B.S.R.A.) (Ref 15) Drawing attention to the universal practice of providing a common oil supply for lubricating both turbines and reduction gearing, this paper reports on engineering tests which were developed ill Pametrada and B.S.R.A PAPERS FOR FURTHER STUDY 99 for evaluating the suitability of lubricating oils This had particular reference to some scuffing troubles which occurred in double reduction gearing in the immediate post war years Much useful information is recorded giving comparative performance of through hardened combinations, and case hardened gears, and also for a standard OM100 specification oil and various extreme pressure oils Correlation between such tests and full scale reduction gears is shown to be good The second part of the paper is devoted to tests for propensity to machining type thrust failures, using a full scale bearing test machine The test results are freely recorded and there are good illustrations of the typical damage to the white metal surfaces The conclusions are that the propensity to machining type failure is a characteristic of the combination of lubricating oil and thrust collar material, the oil being the preponderant factor There is a full and interesting discussion which should be of interest to all operating engineers 8.11 MARINE STEAM TURBINES AND THEIR LUBRICA TION G H Clark (Burmah Oil Trading Ltd.) (Ref 16) A most useful review of recent practice and operating experience with marine turbines, with particular reference to the lubricating aspects of the turbines and gearing Interesting information is given on gearing defects (covering tooth fracture, pitting, scuffing and other forms of wear), on corrosion of white metal, and with further information on thrust bearing failures 8.12 MARINE STEAM TURBINES-SOME POINTS OF DESIGN AND OPERATION K M B Donald (Lloyd's Register of Shipping) (Ref 24) This paper stresses the importance of reliability in marine turbines and mentions most of the defects which have ever given trouble-blade erosion, blade fouling with deposits, gland rubbing, blade tip rubbing, blockage of drains, lacing wire brazing failure, thermal shock effects, horizontal joint warpage and consequent leakage, effect of hull deflections and machinery misalignment, blade and disc vibrations, and rotor vibration There is a valuable section on the balancing of flexible rotors, a description of what happens theoretically when passing through a critical speed, and of the modal balancing technique There is also a section on vibration limits in marine turbines, and a chart relating measured vibration levels to acceptable or unacceptable criteria 8.13 VIBRATION DIAGNOSIS IN MARINE GEARED TURBINES H G Yates (first Chief Designer of Pametrada) (Ref 23) This paper, delivered in 1949, is a classic which should be read by anyone interested in understanding more about the fundamentals of vibration and how the causes can be diagnosed Special instruments and techniques devised for this purpose are described, together with simpler instruments of pocket size 100 8.14 MARINE BLADE FAILURES AND THEIR IN THE ENGINEERING H.P PRACTICE TURBINES OF R.M.S Queen Elizabeth RECTI FICA TION R Fleeting and R Coats (Ref 39) The H.P turbines of Queen Elizabeth both suffered from blade failures on the proving voyage prior to acceptance by the owners The failures were recognized to be due to fatigue and investigations took place to establish the cause The paper records the history of the operation of the engines up to lhe lime of failure, which had included trials up to the fuII power of 82 027 kW (110 000 shp) and reports on the damage sustained It reviews the blade vibration aspects, establishing the theoretical backgound and discussing the response to external and steam excitation The rectification of the fault by a redesign, incorporating a binding wire, is described This paper must be of considerable interest to anyone interested in the design and operation of steam tal Oli!" machinery Necessarily, the treatment of the vibration problem is very techmcal, but there is a useful correlation between the theoretical treatment and the practical results There are many helpful diagrams and photographic illustrations, with an interesting discussion and the paper is recommended for detailed study 8.15 MARINE BEARINGS A Rose (MichelI Bearings) (Ref 26) Although this excelJent paper is essentially on design, it wilJ be of great value to the operating engineer in giving him an understanding of the principles of operation WelJ established methods are given for calculating film thickness and power losses of fluid film hen rings, and nomograms and charts are given to facilitate this These meli, ,;"er plain journal bearings as welJ as three pad half bearings and six pad fulJ bearings Methods and a chart are given for determination of oil film thickness, power loss, oil flow and temperature rise in the oil There is a section on high speed bearings as used for turbines, which discusses the difference between zero speed oil flow and maximum speed hydro dynamic flow, and gi-ves methods for calculation Design criteria are given for turbine thrust bearings, and an interesting curve is given showing the effect of various degrees of misalignment on thrust pad pressures PAPERS FOR FURTHER STUDY 101 There are good descriptions on the various types of bearing failures, covering wiping of white metal, electrical damage, fatigue, machining type as previously discussed, and tin oxide corrosion There is also a helpful section on materials and manufacture, including the specialized business of white-metalling bearings As usual, there is a most useful discussion and correspondence which add to the value of the paper 8.16 M.S.T 14, SYSTEMS A PROTOTYPE FOR MARINE STEAM TURBINE PROPULSION J W Mann (GEC) (Ref 4) This paper describes the General Electric Co 1965 steam plant designed to meet the marine industry's need for ratings between 14914 and 37 285 kW (20000 and 50000 shp) and includes the application of reheat, shaft driven auxiliaries and other advanced concepts In designing this plant, a key parameter was low specific fuel consumption without compromising the ease of maintenance and reliability of the plant 8.17 RESEARCH, DEVELOPMENT AND DESIGN FOR MARINE PROPULSION GEARED STEAM TURBINES K Brownlie and I T Young (English Electric-AEI) (Ref 28) This review of turbine and gearing developments also makes reference to detail design features included in the marine propulsion sets of the company's design and manufacture This is the only British firm now designing and manufacturing marine steam turbines The paper refers to the single cylinder steam turbine for moderate powers, and the extension to higher powers by the use of multi exhausts for the last two stages Information is given on erosion of low pressure end blades and reference is made to the attachment of erosion shields by electron beam welding There is also a description of turbine control equipment and the partially pressure balanced, single seat venturi type manoeuvring valves The rest of the paper is devoted to gearing developments 8.18 THERMAL STRAIGHTENING OF TURBINE ROTORS H G Yates (Pametrada) (Ref 35) This paper gives an excellent explanation of the way in which a rotor develops a permanent bend as the result of interference between the shaft and the gland strip or any other stationary part The rest of the paper is devoted to the thermal straightening processes which can be judiciously applied to rotors which have suffered such a permanent bend, a process of considerable interest, but one which should properly be left to the expert 102 MARINEENGINEERINGPRACTICE 8.19 MITSUBISHI ~AR'NE STEAMTURBINE Mitsubishi Heavy 1Ildu:;lries Ltd (Ref 36) This excellent brochure describes the full range of Mitsubishi Escher Wyss Turbines, of the power range 7457kW (IOOOOshp) (MT-lOO) to 2~828kW (40000shp) (MT-400) It is well illustrated with pictures of completed machines and major components at various manufacturing stages 8.20 A 36000 SHP MARINE STEAMTURBINE WITH MAIN TURBINE DRIVEN AUXILIARIES S Yamate (Mitsubishi Heavy Industries Ltd.) (Ref 37) This paper describes the 26845 kW (36000 shp) at 90 rev/min steam turbine propulsion unit built for a mammoth tanker There is an interesting table showing the fluctuation in propeller revolutions measured in a 156500 dwt tanker at sea 8.20.1 Recent Developments of Marine Turbine Technology in Japan: Section 2, Steam Turbines (Ref 38) Information is given of recent developments in marine steam turbine machinery and a table summarizes the particulars for three different types of reheat cycle plant IHI R-804, Kawasaki UR and Mitsubishi MR There are illustrations of recent installations 8.21 DEVELOPMENTOF A JAPANESE DESIGN OF MARINE STEAM TURBINE PLANT Y Takeda (Kawasaki) (Ref 31) This paper records the progress of Kawasaki marine steam turbines and gives a great deal of useful material which forms the background of this development There is a useful discussion with examples of blade failures due to corrosion, splitting and cracking 8.22 DEVELOPMENTSIN MARINE STEAMTURBINE DESIGN T W F Brown (Ref 30) This paper discusses the necessity for research as a means of refining design Many lines of research can be actively pursued which in the aggregate lead to great improvement in reliability and economy at any temperature level There are good illustrations of Pametrada practice for both steam turbines and gearing, but the most interesting section of the paper is the description of research work which led to changes in the detailed designsuch as in welded diaphragms, flexible couplings including the effect on coefficients of friction of different surface treatments, through hardened and surface hardened gears, hydraulic reversing transmission, blade windage, turbine distortion, and L.P blading and erosion shields There is an interesting section on the whirling of rotors and oil whip (or oil whirl), the name given to a certain type of vibration sometimes experienced by a rotor running in oil-film bearings REFERENCES 103 Since this paper was written considerable advances have been made in the certainty of the bearing oil film effect and the pedestal flexibility effect which enable such calculations to be carried out with assurance 8.23 MARINE MACHINERY FAILURES B K Batten (Lloyd's Register) (Ref 32) In common with most accounts of failures, this paper is of great interest, and includes a few items relating to turbines, gears and clutches There is a good illustration of a blade fatigue failure in way of a lacing wire when the blades were of chrome stainless steel while the wire was non-magnetic austenitic stainless steel There is also information on a bent H.P rotor and a fracture in way of a separate shrunk-on thrust collar due to fretting and bending fatigue The discussion adds greatly to the value of the paper, in giving further examples of machinery failures Also in the discussion is an illustration of a triple reduction gear arrangement of the Stal-Laval/W H Allen design REFERENCES I "Advanced Propulsion Systems" 1968 Stal-Laval Publication Jung, I 1969 "Steam Turbine Machinery" Trans I Mar E Vol 81, pp 137-161 "MST 13 Marine Steam Power Plant for Turbine Driven Tanker" 1962 General Electric Company (USA) Publication Mann, J W 1969 "MST 14-A Prototype for Marine Steam Propulsion Systems" Proc IMAS 69, Section 4d, pp 24-35 "Pametrada Geared Turbines" 1966 Pametrada Publication Coats, R 1965 "Pametrada Standard Turbines, Present Position and Future Outlook" Trans I Mar E Vol 77, pp 327-352 Jackson, G S and Winyard, C 1964 "Northern Star: Evolution and Operation" Trans / Mar E Vol 76, pp 229-265 Brown, T W F 1957 "Propulsion of Ships by Steam Turbine Machinery" De Laval Memorial Lecture General Electric Company 1972."Marine Propulsion Steam Turbines" First International State of the Art Seminar 10 Somes, A D 1959 "Advances in Steam Turbines for Marine Propulsion" Trans I Mar E Vol 71, pp 211-232 II Coats, R 1971 "Modem Marine Steam and Gas Turbines" MER Dec., pp 14-20 12 Brown, J F C and Goundry, E E 1967 "Bearing Whitemetal Corrosion-An Electrochemical Explanation" B.S.R.A Report NS 153 104 MARINE ENGINEERING PRACTICE 13 Landsdown, A R and Hurricks P L 1973 "Interaction of Lubricants and Materials" Trans / Mar E Vol 85, pp 157-168 14 Coats, R 1965 "Marine Turbin" Thrusts" Trans NECIES Vol 81, pp 305-338 15 Darling, R F and Isherwood, T 1967 "Engineering Tests for Marine Turbine Lubricating Oils" Trans I Mar E Vol 79, pp 25-50 16 Clark, G H 1973 "Marine Steam Turbines and their Lubrication" MER Jan., pp 17-20; Feb., pp 35-40; March, pp 31-34 17 Quinlan, J J and McAllister, F G 1971 "The Case for Condensate Filtration in Marine Steam PC'wef Plants" MER Sept., pp 20 21 18 Gilbert, P T 1970 "Corrosion Problems in Condensers and Heat Exchanges" MER July, pp 6-10 19 Ashworth, J L., Hall, J S and Gray, A H 1954 "The Electrical Measurement of Steam Turbine Rotor Movements, with Special Reference to the Operation and Design of Modern Power Plant" Proc J.E.E Vol 102A, pp 131-146 20 Terrell, B.J 1954."The Influence of Thermal Effects on the Manoeuverability of Marine Machinery" Trans NECIES Vol 71, pp 51-66 21 Brown, T W F 1963 "Shore Trials of Marine Steam Turbine Machinery" Trans I Mar E Vol 75, pp 261-296 22 Veitch, A F 1961 "Marine Steam Turbine Design and Operation" Trans NECIES Vol 77, pp 225-248 23 Yates, H G 1949 "Vibration Diagnosis in Marine Geared Turbines" Trans NECIES Vol 65, pp 225-262 24 Donald, K M B 1973 "Marine Steam Turbines-Some Points of Design and Operation" Trans I Mar E Vol 85, pp 25-50 25 Carmody, T 1972 "The Measurement of Vibration as a Diagnostic Tool" Trans I Mar E Vol 84, pp 147-159 26 Stal-Laval 1968 "The Treatment of Condenser Cooling Water by Ferrous Sulphate" 27 Rose, A 1967 "Marine Bearings" Trans / Mar E Vol 79, pp 233-268 28 Brownlie, K and Young, L T 1969 "Research, Development and Design for Marine Propulsion Geared Steam Turbines" Proc IMAS 69 Section 4d, pp 48-64 29 Platt, E H W 1965 "Marine Engineering in the Royal and Merchant Navies" (The 24th Andrew Laing Lecture) Trans NECIES Vol 82, pp 17-40 30 Brown, T F W 1960 "Developments in Marine Steam Turbine Design" Trans I.E.S Scotland Vol 104, pp 82-173 31 Takeda, Y 1970 "Development of a Japanese Design of Marine Steam Turbine Plant" Trans / Mar E Vol 82, pp 153-170 32 Batten, B K 1972 "Marine Machinery Failures" Trans I Mar E Vol 84, pp 271-292 REFERENCES 33 34 35 36 37 38 39 40 105 Hutchison, T B 1966 "30000 shp Unitized Reheat Steam Turbine Propulsion" Trans I Mar E Vol 78, pp 109-181 Hims, H E C and Frederick, S H 1961 "Materials for Advanced Steam Conditions and their Influence on Operation of Marine Turbines and Boilers" Trans I Mar E Vol 73, pp 325-347 Yates, H G 1954 "Thermal Straightening of Turbine Rotors" Trans / Mar E Vol 66, pp 77-79 Mitsubishi Heavy Industries Ltd 1964 "Mitsubishi Marine Steam Turbine" Yamate, S 1969 "A 36 000 shp Marine Steam Turbine Driven Auxiliaries" Trans IMAS 69 Section 4d, pp 15-23 "Recent Developments of Marine Turbine Technolo,gy in Japan Section Steam Turbines" 1972 International Symposium on Marine Engineering, Tokyo Fleeting, R and Coats, R 1970 "Blade Failures in the H.P Turbines ofr.m.s Queen Elizabeth 2" Trans I Mar E Vol 82, pp 49-74 Crowdig, E P and Pearson, H M 1966 "Machinery for Fleet Replenishment Tankers" Trans NECIES Vol 82, pp 59-141 ... Conditions 62 bar/51Ooe (900 Ib/in2 g/950°F) 59 bar/ 510 oe (85 0 Ib/in2 g/950°F) 10 0 bar/ 510 oe (14 50 Ib/in2 g/950°F/950°F) 59 bar/ 510 oe (85 0 Ib/in2 g,950°F) Reheat 86 bar, 513 °Cj51Ooe MARINE ENGINEERING... turbines 14 MARINE ENGINEERING PRACTICE THE MODERN TURBINE 15 16 MARINE ENGINEERING PRACTICE 18 MARINE ENGINEERING PRACTICE 20 MARINE ENGINEERING PRACTICE THE MODERN TURBINE 21 22 MARINE ENGINEERING... trials in 19 63 Figures 12 and 13 show the H.P turbine from this set 8 MARINE ESGIN' ~:RING PRACTICE THE MODERN TURBINE 10 2.3 MARINE CONSTRUCTIONAL ENGINEERING PRACTICE FEATURES 2.3 .1 Pametrada