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

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-d-”overcome, careful consideration must still be given to strengthdegradation, locked-in stresses and distortion in way of welds.oFYoblems with isolation of dissimilar metals, particularlyat mechanically-fastened joints between aluminum and steelstructures exposed to salt water. Additional problems occurwith installation of piping and equipment, shafting, propellers~mooring and anchor gearj etc.o LowfizwreSistanc eofalumi,numst?Wcturw. Th3sha9 requiredextensiveinvestigation due to the low melting point of aluminum andgross loss of structural integrity resulting from fire.oooExfoliation of the 5456 alloy in the N&vy patral andassault craft, and crevice corrosion in way of welds anddiscontfiuities.Use of improper primer/paint systems.Improper fabrication of aluminum weldments due to lack ofqualified welders. This problem has largely disappeared atfacilities where a significant quantity of thei~ productionis of aluminum construction.The aforementioned limitations and problem areas have tended torestrict the use of aluminum to smaller hulls and other specializedapplications in the marine field until recent years. However, as thetechnical problems have been overcome and the state of the art in fabricatingaluminum structures has advanced, aluminum has been consideredand used in larger hulk, including:ooU. S. Navy 8)J foot LCM-8 landing craft.U. S. Navy PGM high-speed patrol craft, 154 feet long.o 2440 Thefoot oceanographic vessel SEA PROBE, now under construction.shallow draft tanker ‘;INDEFENDENCE”,118 feet long.oThetrailership IISAC&rjBORINCANOff,306 feet long.ooooCommercial and military hydrofoils.86 foot aluminum purse seiner, presently under construction.223 foot aluminum barge “ALUMINIL”.160 foot ferry GTS ‘TAVALONT’.A major factor affecting the future of aluminum in marine applicationsis the recent trend toward evaluation of life cycle cost, in which allfactors affecting the economics of a specific system are evaluated overthe lifetime of the system to determine total cost throughout its li~e.The use of life cycle cost techniques permits the designer and economistto trade-off higher first cost of an aluminum ship against potential fuelsavings or increased earning capacity resulting from lighter hull weight,as well as economies in hull maintenance and higher scrap or resale value.This factor, in conjunction with the recent advances in the state of the
art in fabricating and maintaining aluminum, justifies consideration ofaluminum in the construction of a large hull such as the bulk carrierpresently under consideration.-3-Scope ofStudyThis program consisted of four phases:-.o Material and Design Studies including a review of alloyproperties, development of criteria, methods of fabrication,fire resistance , effect on systems and effects on operations.0 Comparative Ship Design and Evaluation, including modificationof the selected steel bulk carrier to suit 1969 strengthstandards, and design of an equivalent aluminum bulk carrier:dimensions, midship section, weights, and construction cost.o Cost Studies, wherein equivalent steel and aluminum bulkcarriers are analyzed to determine relative required freightrates over several trade routes and for operating lives offrom 20 to 30 years. These studies are conducted for bothsingle hull and multi-hull procurement.o Recommended Areas for Further Study wherein a research programiS proposed for extending this study in areas requiring furtherinvestigation.The study was originally specified to be based upon comparison to anexisting US-built bulk carrier or a realistic design study reflectingABS requirements. Since few, if any, large ocean going high-densitybulk carriers have been built in this country in the past 20 years,this study is based on a hypothetical ship which is physically identical*O a recent large foreign built bulk carrier approvedby ABS. All costfactors are based upon construction in the United States and operationunder the American Flag. This approach is considered preferable tobasing this work on a design study, since the physical characteristicsof the existing base line ship are well doc~ented and fully proven inservice.Selection of Bulk CarrierThe ship selected as a basis for developing the hypothetical highden.sitybulk carrier is the M.V. CHALLENGER. This ship is an ocesn goingflush deck bulk carrier with raised forecastle and poop, 6 cargo holdsand machinery aft. The characteristics of the CHALLENGER are summarizedin Table 1.
Page 5: CONTENTSI.. II.III.Iv.v.VI ●VII.I
Page 9 and 10: LIST OF FIGURES(Cent’d)FIGURE NO.
Page 11: I. INTRODUCTIONThis report summariz
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
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-54-000000000Bottom Shell PlateSide
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-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
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.66-INSUT.ATION AND SHEATHINGShell8
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-68-(b)(c)(d)(e)(f)(g)(h)(i)(j)At l
Page 80 and 81:
-70-IIF.INSTALLATION OF SYSTEMS AND
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Rudder Assembly -carrier should be
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-74-(b)MechanicalTensile Strength 6
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-76-(e)The steel piping must be of
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-78-Other Piping Systems and Valves
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-80-struetion for the aluminum hull
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-82-Large heavy type machine~ must
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suffers attack in an alkaline envir
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-86-REPAIRSObtaining proper repairs
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-88-The design of the midship s~cti
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-90-assuming the increase is applic
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LIGHT SHIP WEIGHT ESTIMATE-92-In or
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-94-TABLE 20 Aluminum Bulk Carrier
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TABLE 22 Trim and StabilityFull Loa
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-98-TABLE 24 Price of Steel Bulk Ca
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GaseNumber. . . -.,- .TABLE 27 Comp
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-1o2-TABLE 28CarriersComparison of
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12 ---n..T.[T7%l,=LEGS IU ORF=ErY
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-106-such as iron ore, on two of th
Page 118 and 119:
-108-7)is,zg~ gg~5e mzz~E’4E!~K2j
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-11o-(a)(b)(c)(d)Inerting system fo
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-112-fatigue, particularly in the p
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-114-2k* Installation of Systems an
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-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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