ship production

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Ship Production

Lecture 10 – Shipyard Processes

Shipyard Processes:

• Ship Drawing offices & Loftwork

• Plate & section preparation & machining

• Welding & cutting

• Subassembly

• Prefabrication

• Launching

• Outfit

• Corrosion control & paint systems

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Plate & Section Preparation :

Steel plates & sections shot-blasted to remove rust & millscale, primed with temporary protective paint.

Plate & Section Preparation – Shot Blasting :

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Plate Section Preparation :

Steel plates straightened using roll machines (mangles).

Plate & Section Preparation :

Plate handling may be performed by:

• Overhead electric cranes

• Electric powered trolleys – collacator unit running on rails

• Transporter lowloader

• Conveyor systems and integrated units

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Plate & Section Preparation - Handling:

Plate & Section Preparation - Handling:

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Plate & Section Machining:

Number of methods for forming plates into required shapes.

Information derived from CAD/CAM systems

• Profile cutting machine

• Planing machines

• Drilling machines

• Guillotines

• Presses

• Plate rolls

• Heat line bending

Plate & Section Machining - Profilers:

Employed when plate is required to be cut into two or more plates or complicated shapes. Usually flame or plasma-arc.

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Plate & Section Machining - Planing:

Some plates only require trimming and edge preparation – carried out using planing machine.

• Flame or plasma-arc

• Mechanical


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Plate & Section Machining - Presses:

Hydraulically powered press to cold work steel press.

Capable of:

Bending, straightening, flanging, dishing, swaging.

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Plate & Section MachiningPresses:

Plate & Section Machining - Presses:

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Plate & Section Machining – Plate Rolls:

Heavy duty bending rolls used for rolling shell plates.


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Plate & Section Machining ‘Heat-Line Bending’:

Heat applied to plate using flame.

Then immediately cooled.

Plate bends.

More time consuming than rolls but plate will hold shape more accurately.

Plate & Section Machining ‘Heat-Line Bending’:

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Plate & Section Machining Frame Bending:

Cold bend by application of horizontal ram whilst frame held by gripping levers

Plate & Section Machining Frame Bending:

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Welding & Cutting:

To be discussed in detail next week…

Subassembly:

Many large modern shipyards use panel lines for the production of stiffened panels.

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Subassembly :

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Subassembly :

Prefabrication:During WWII mass production techniques adopted in shipbuilding.

3d units fabricated using 2d components

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Prefabrication:

Prefabrication:

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Block Assembly:

Block Assembly:

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Block Assembly:

Block Assembly:

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Block Assembly:

Block Assembly:

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Block Assembly:

Block Assembly:

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Launching:

To be discussed in detail in a fortnight…

Outfit:

• Pipework

• Ventilation

• Linings/insulation

• Public Spaces

• Cabins

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Outfit - Piping:

Outfit – Ventilation:

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Outfit - Insulation:

Outfit – Public Spaces:

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Outfit - Cabins:

Corrosion - Nature & Forms :

Atmospheric corrosion – serious rusting may occur where the relative humidity is greater than 70%

• Corrosion due to immersion – when in service bottom region is completely immersed, ideal conditions for electro-chemical corrosion.

• Electro-chemical – flow of electricity from one metallic region to another through electrolytic solution, e.g. salt water.

• Galvanic – due to coupling of dissimilar metals to form a corrosion cell, e.g. steel hull & bronze propeller.

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Corrosion - Nature & Forms :

Noble (protected)Platinum, GoldSilverTitaniumStainless steels, passiveNickelBronzeCopperNickelBrassLead, TinStainless steels, activeSteelAluminiumZincMagnesium

Ignoble (corroding)

Corrosion Control :

• Sacrificial anode – metals attached to hull which are more anodic (less noble) than steel when immersed in salt water, e.g. zinc plates.

• Impressed current systems – voltage difference maintained between hull and fitted anodes. May use noble metals as anodes to reduce deterioration.

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Paints:

• Anti-foul paints – self polishing anti-foul paints can last up to 5 years. Now Tributylen Compound (TBT) free due to International Maritime Organisation (IMO) requirements.

• Paint coating to prevent corrosion.

What differences would be visible when constructing a composite vessel?

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Composite Vessel:

• Mould construction

• Materials storage & resin shelf life

• Safety & quality considerations

• Laminating sequences

• Curing times

• Crane requirements

Composite Vessel:

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Composite Vessel:

Composite Vessel:

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Composite Vessel:

Composite Vessel:

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Composite Vessel:

Composite Vessel:

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Aluminium Vessel:

• Welding/cutting techniques

• Labour intensive

• Painting requirements

• Crane requirements

Aluminium Vessel:

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Further reading:

Eyres, D., Ship Construction, 5th Edition, Butterworth-Heinmann, Oxford, UK, 2001.

Taylor, D., Merchant Ship Construction, 4th Edition, Institute of Marine Engineers, London, UK, 1998.

Taggart, R., Ship Design and Construction, SNAME, New Jersey, USA, 1980.

Storch, R., Hammon, C., Bunch H., and Moore R., Ship Production, 2nd Edition, SNAME New Jersey, USA, 1995.

Lamb, T., Ship Design and Construction I & II, SNAME, New Jersey, USA, 2003.

Lewis, E., Ed. Principles of Naval Architecture: Volume I - Stability and Strength, SNAME, New Jersey, USA, 1988.

Shenoi, R. & Wellicome, J. (Ed.) Composite Materials in Marine Structures. Volume 1 Fundamental Aspects. Volume 2 Practical Considerations, Cambridge University Press, Cambridge, UK, 1993.

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ship production

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