Turbine Engine Oils - VPS Lubricants

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80Turbine Engine OilsAs a general rule, Shell Companies do not make recommendationsregarding compatibility, since aviation applications are critical and thedegree of compatibility depends on the operating conditions, performancerequirements, and the exact composition of materials. In many cases theequipment manufacturers perform their own compatibility testing or havetheir elastomer supplier do it for them. Many elastomer suppliers doproduce tables showing the compatibility of their products with a range ofother materials. Therefore, the information provided here can only beconsidered as a guideline.Elastomer/Plastic Mineral Turbine Synthetic EsterOilsTurbine OilsFluorocarbon (Viton) Very good Very goodAcrylonitrile Good Poor to Good(high nitrile contentis better)Polyester Good Poor to FairSilicone Poor to Good Poor to FairTeflon Very Good Very goodNylon Poor to Good PoorBuna -S Poor PoorPerbunan Good Fair to GoodMethacrylate Good Poor to FairPAINTSEpoxy resin paints have been found to be practically the only paintsentirely compatible giving no breakdown or softening or staining in use,except for the very light colour shades, which are susceptible to stainingdue to the actual colour of the anti-oxidant inhibitor contained in practicallyall ester based lubricants.PLASTICSOnly the more common plastics can be considered for evaluation ofcompatibility.The best from chemical and physical aspects is polytetrafluoroethylene, asmight be expected from its generally inert properties. This is closelyfollowed by higher molecular weight nylon. Polyvinyl chloride is rapidlysoftened by the hot oil and is not recommended. Currently, polythene andterylene are also suspect in this respect, but have not been extensivelyevaluated.VARNISHESMany commonly used phenolic impregnated varnishes are softened bycontact with the hot oil, but a few of the harder grades show moderate togood resistance. Silicone varnishes and TS 188 are considerably softened.Modified alkyd type varnishes, when baked, possess good resistance to oilbut have poor resistance to water. When good resistance to water is alsorequired, it is recommended that the varnish be coated with a waterresistant finish.Turbine Engine Oils81Neoprene Fair to Good PoorMINERAL AND VEGETABLE OILSEster based synthetic oils are incompatible with mineral and vegetable oils.In no circumstances should these products be used together and, ifchanging from one type to another, then particular care is needed toensure that all traces of the previous product are removed prior to esterlubricant application.Natural Rubber Poor to Fair PoorPolyethylene Good GoodButyl Rubber Very Poor to Poor Poor to FairPoly Vinyl Chloride Poor to Good PoorMETALSCopper and alloys containing copperAs in mineral oil applications, pure copper has a marked catalytic effect atsustained high oil temperatures on the break down of the esters to acidderivatives, and its use in engines or other equipment is thus mostundesirable. Copper alloys such as brass and bronze do not possess thisproperty to any great degree and can be used with safety.Compatibility Rating:Very Good – Good – Fair – Poor – Very Poorwww.shell.com/aviationThe AeroShell BookEdition 18 2003
Aluminium and steel and their alloysThese materials are not affected.Nickel and alloys are generally satisfactory.Tin plating is generally satisfactory.For aircraft oil tanks the recommended material is light alloy or stainlesssteel.82Turbine Engine OilsCadmiumCadmium, in the form of plating as a protective treatment for storage ofparts destined to be in contact with oil in service, experiences a tendencyat the higher temperatures to be taken into solution by synthetic oils. Thissolvent action does not harm the lubricant, but the slow removal ofcadmium plating after many hours of service will detract from its efficiencyas a subsequent protective.Lead and alloys containing leadLead and all alloys containing lead are attacked by synthetic lubricants.The way the lubricant reacts with the lead differs according to the type oflubricant, but in general, all lead compounds should be avoided. The mostcommon forms of lead are lead abradable seals and lead solder usedparticularly in filters and mesh screens. In these cases the mesh screenshould be brazed.OTHER METALSMagnesium is not affected except where hydrolysis occurs. Thusmagnesium should not be used if there is any likelihood of hydrolysisoccurring or alternatively the magnesium could be coated with epoxy toprotect it.Monel and Inconel are not affected.Tungsten accumulates a very thin soft black film after prolongedimmersion in synthetic oils under static conditions. It is readily removed bywiping, leaving no sign of corrosion. Under the scrubbing conditionsnormally associated with circulatory oil systems this film does notmaterialise and its effect may be ignored.Zinc, as galvanised protective, is attacked by synthetic lubricants leadingto the formation of zinc soaps and thus should not be used. Storage ofsynthetic oils is best achieved in tinned mild steel cans or failing this, brightmild steel.Titanium is not affected.Silver and silver plating is generally not affected. However, in somesynthetic ester oils, the additive pack, especially high load additives, reactwith the silver and blacken or even de-plate the silver.Chromium plating is not affected.NON-AVIATION USE OF AEROSHELL TURBINE ENGINE OILSIn selecting an AeroShell turbine engine oil for a non-aviation application,the properties of the oil must be examined. This will only give anapproximate indication as to the expected performance in the specificapplication. However, such data must be regarded as guidance only. Thereis no laboratory test that can give a complete prediction of performance inactual use, and the final stage in any decision must involve performancetests in either the actual equipment or in the laboratory/test house underconditions expected in service.The main use of AeroShell turbine engine oils in non-aviation applicationsis in aero-derived industrial and marine gas turbine applications. Suchengines have found application in:- electrical power generation- large pumps and compressors, especially in pipeline applications and inpetrochemical process industry- marine propulsionIn an aero-engine, essential design features are it’s size and weight, whichresults in compact units. Such designs place heavy demands on the enginecomponents and lubricants to ensure total reliability in the hightemperatures within the engine.The land and sea based derivatives of the aero-engines retain the essentialdesign elements of their aviation versions and thus have similar lubricationrequirements. Engine manufacturers therefore approve the use of aircraftsynthetic turbine oils in these engines. Only these lubricants have thecharacteristics required to provide the unit lubrication and cooling withinthe severe operating environment.There is a full range of AeroShell turbine oils approved by the majorengine manufacturers for use in their industrial and marine derivatives ofaero-engines and a quick reference table is included at the end of thissection.Turbine Engine Oils83www.shell.com/aviationThe AeroShell BookEdition 18 2003
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Page 7: AEROSHELL TURBINE OIL 286Turbine En
Page 10 and 11: PROPERTIES OST 38.01163-78 TYPICALS
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Page 16 and 17: PROPERTIES MIL-PRF-23699F TYPICALGr
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Page 24 and 25: AEROSHELL TURBINE OIL 560AeroShell
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