design considerations for aluminum hull structures - Ship Structure ...

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-70-IIF.INSTALLATION OF SYSTEMS AND FQUIPMENTMATERIALShavePropellers - For cormnercialship application the majority of propellersbeen of the following materials:Material-AlloyManganese BronzeNickel Manganese BronzeNickel Aluminum BronzeManganese Nickel Aluminum BronzeTrade NameTurbine MetalNialite awl NikaliumSuperstonWhen these materials are coupled to aluminum in sea water a galvaticcell is created and the aluminum hull platim, rudder. etc. will be anodicto the bronze and will act as an anode-to pr~~ect thi~ vexy large area ofbronze cathode and the ahmin-mnwill corrode vexy rapidly. A cathodicprotection system can be installed to protect the aluminum underwater structure.Another material which is more compatible with aluminum in sea watershould be considered. Such a material is 18 per cent chrome - 8 per centnickel stainless steel alloy, similar in composition to the Alloy CastingInstitute Specification CF-8 (corresponding wrought alloy type is AISI 304).This alloy has been used successfully for many years on the 29 ships builtbetween 1962 and 1968 for Lykes Bros. and Gulf & South American Ships.These propellers vary from ~2,000 to 76,000 pounds in weight and are about21 feet in diameter.The chemical, mechanical and physical properties of this CF8 materialare as follows. (CF8 alloyis also similar to ASTM Specification A296-GradeCF8).(a)(b)(c)ChemicalCarbonM@aneseSiPsChromeNiMechanicalTensile StrengthYield StrengthElongation in 2 InchesBrinell HardnessCharpy ImpactPhysical ConstantsDsnsitySpecific HeatPer Cent0.08 w.1.50 Max.2.00 k.0.04 k.0.04 Max.18 to 218 to 1165,000 PSI Min.30,000 PsT Mill.~~oPer Cent75 Ft-Lbs0.280 Lbs/Cu.In.0.12
-71”(d)Welding ProceduresPreheatPostheatNoneNone - if area is smallThese propellers are of the built-up type with the blade palms boltedto the cast hub. The propeller blades and hub are cast stainless steel CF8alloy, while the studs for attaching the “bladesto the hub are monel 1%00(Kmonel) and the nuts for studs are Armco 17-@Hcondition H-11~0.The CHALLENGER propeller is presently a solid five-bladed of bronzematerial ad is 18 feet b-1/2 inches in diameter. An est~ated weight andcost comparison is shown in the following table:MaterialmFinishedWeight - Lbs. Cost Per ‘TotalApproximate Pound, $ cost, $Ni Al Bronze Solid 37,500 1.50 56,2S0CF8 - Cast Built-up L8,000 1.25 60,000Stainless SteelThe cast stainless steel propeller will weigh more since the hub has to belarger in diameter to accommodate the palms of the blades.13asedupon the foregoing, cast staitiess steel, CF8 alloy is recommendedfor the propeller of a large aluminum-hulledvessel.Shafting - The shafting for the CJIHJXNGER is presently made of AmericanBureau of Shipping Grade 2 steel and the diameters were based on the AmericanBureau of Shipping rules that were in existence at the time the vessel wasconstructed in 1965. ‘Thisship has an engine with a metric BHP of 9600 anda propeller RPM of 119. The diameter of the shafts are 16-3/4 inches (lineshaft) and 19-1/2 inches (tailshaft). The tailshaft has no liner since anoil lubricated stern tube bearing was installed.In this application it is suggested that the American WreauShipping Grade 2 steel material be retained for the shafting.ofStern Tube, Beari~ s and Seals - The existing steel hulled ship, hasa cast steel stern tube welded into the stern frame casting at the aft endand into the engine room aft watertight bulkhead at the forward end. Thearrangement is generally as shown on Figure 14.There are two stern tube bearings of the oil lubricated type (Waukeshatype), one long bearing 43-1/2 inches long at the aft end of the tube anda shorter one, 17-3/4 inches long, at the fcrward end of the tube.The materials of the existing assembly as installed in the steel hullship and the suggested materials for the aluminum hull ship are shown inthe table in Figure 14.All bolts, nuts and studs for the seals and glands exposed to seawater should be made of a combination of 304 or 316 stainless steels, inother words, if the studs or bolts are 304 then the nuts should be 316,or vice versa, to prevent galling.
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CONTENTSI.. II.III.Iv.v.VI ●VII.I
Page 9 and 10:
LIST OF FIGURES(Cent’d)FIGURE NO.
Page 11 and 12:
I. INTRODUCTIONThis report summariz
Page 13:
art in fabricating and maintaining
Page 16 and 17:
MONTEROSSO GRANA /17VALGRANA / CARA
Page 18 and 19:
-8-Numerous references have been re
Page 20 and 21:
.10.TABLE 2. Mechanical Properties
Page 22 and 23:
TABLE 2 Mechanical Properties of Al
Page 24 and 25:
TABLE 3 Mechanical Property Limits
Page 26 and 27:
-16-l?igures5, 6, 7 ati 8 present f
Page 28 and 29:
-18-ti-’”’-”-””””-L
Page 30 and 31: -20-60 .r---.— ..,.— -——,L-
Page 32 and 33: .22-each stress level, rate of load
Page 34 and 35: -24-!Z456-H321 = 0.485083-H321 = 0.
Page 36 and 37: -26-(c)Members with partial or cont
Page 38 and 39: -28-AllOyS 5083 and 54.56(~ content
Page 40 and 41: -30-The previous paragraphs have de
Page 42 and 43: -32-The problem of cargo hold abras
Page 44 and 45: -34-The question of residual stress
Page 46 and 47: .36-Each alloy was given a relative
Page 48 and 49: -38-GENERAL OBSERVATIONSFYior to a
Page 50 and 51: -40-The question of comparative imp
Page 52 and 53: -42-(d)(e)Poor quality welds due to
Page 54 and 55: -44-The ABS criteria noted above we
Page 56 and 57: -46-DNV would consider fatigue in e
Page 58 and 59: -48-is less, for the exposed side s
Page 60 and 61: Equation (2):-50-Hu1l SMa~um = Hull
Page 62 and 63: -52-Another aspect of vibrations wh
Page 64 and 65: -54-000000000Bottom Shell PlateSide
Page 66 and 67: -56-at the deck and keel. This stre
Page 68 and 69: -58-AT is the change inUT= Thermal
Page 70 and 71: -60-SUl@!ARYAll parties contacted f
Page 72 and 73: -62-(c)(d)(e)(f)T~e exterior side o
Page 74 and 75: TABLE 12 Aluminum Bulk Carrier - Su
Page 76 and 77: .66-INSUT.ATION AND SHEATHINGShell8
Page 78 and 79: -68-(b)(c)(d)(e)(f)(g)(h)(i)(j)At l
Page 82 and 83: Rudder Assembly -carrier should be
Page 84 and 85: -74-(b)MechanicalTensile Strength 6
Page 86 and 87: -76-(e)The steel piping must be of
Page 88 and 89: -78-Other Piping Systems and Valves
Page 90 and 91: -80-struetion for the aluminum hull
Page 92 and 93: -82-Large heavy type machine~ must
Page 94 and 95: suffers attack in an alkaline envir
Page 96 and 97: -86-REPAIRSObtaining proper repairs
Page 98 and 99: -88-The design of the midship s~cti
Page 100 and 101: -90-assuming the increase is applic
Page 102 and 103: LIGHT SHIP WEIGHT ESTIMATE-92-In or
Page 104 and 105: -94-TABLE 20 Aluminum Bulk Carrier
Page 106 and 107: TABLE 22 Trim and StabilityFull Loa
Page 108 and 109: -98-TABLE 24 Price of Steel Bulk Ca
Page 110 and 111: GaseNumber. . . -.,- .TABLE 27 Comp
Page 112 and 113: -1o2-TABLE 28CarriersComparison of
Page 114 and 115: 12 ---n..T.[T7%l,=LEGS IU ORF=ErY
Page 116 and 117: -106-such as iron ore, on two of th
Page 118 and 119: -108-7)is,zg~ gg~5e mzz~E’4E!~K2j
Page 120 and 121: -11o-(a)(b)(c)(d)Inerting system fo
Page 122 and 123: -112-fatigue, particularly in the p
Page 124 and 125: -114-2k* Installation of Systems an
Page 126 and 127: -116-LIST OF REFERENCES(7)Fatigue P
Page 128 and 129: -11.8-LLST OF REFERENCES(Cent’d)(
Page 130 and 131:
-120-ADDITIONAL SOURCES OF INFORMAT
Page 132 and 133:
-122-redistribution of the still wa
Page 134 and 135:
-124-APPENDIX BEXCERPTS FROMRULES A
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-126-92.07-10(d)(~) Interior stairs
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-128-~gE1+0102030- .. ..—405060
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ectintyclassification4KEYWORDSROLEL
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SHIP STRUCTURE COMMITTEE PUBLICATIO
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