INDEX

1. INTRODUCTION

1.1) Hindustan Shipyard Limited 1.2) The Organisation 1.3) Ship Building Methodology 1.4) Ships

2. HULL SHOP LAYOUT

2.1) Hull Shop 2.2) Bay 1 Machines And Specifications 2.3) Bay 2 Machines And Specifications 2.4) Bay 3 Machines And Specifications 2.5) Bay 4 Machines And Specifications

3. HULL SHOP PROCESS

3.1) Heat Treatment Line 3.2) Plasma Arc Cutting Machine 3.3) NC Programming 3.4) CNC Flame Cutting Machine 3.5) Hydraulic Guillotine Shear

4. SUMMARY 4.1) Synopsis 4.2) Conclusions 4.3) Bibliography

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1. INTRODUCTION

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HINDUSTAN SHIPYARD LIMITED

INDIAN SHIP BUILDING INDUSTRY:

There are five major shipyards owned by the Central Government. Hindustan Shipyard Limited (HSL) and Cochin Shipyard Limited (CSL) are commercial units. While the rest-GRSE. Mazagon Dock Limited (MDL) and Goa Shipyard Limited (GSL) are Defense yards where in 95% of the orders of which pertain to building of warships for the navy and patrol vessels for Coastguard.

The defense yards have no competitors and need not bid for international tenders to secure orders. There is an element of support to that defense yard in terms of material cost and currency the estimated cost. That way they are better placed than the two civilian yards in respect of order book position.

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1.1) Hindustan Shipyard Limited

(A Government of India Undertaking)

1.1.1) Introduction:

Hindustan Shipyard Limited is strategically located on the east coast of India at Visakhapatnam in Andhra Pradesh. Original set-up under private management in 1941. The Shipyard was taken over by the government of India in 1952. The shipyard functions under the administrative control of ministry of shipping, Road Transport and Highway, Govt. of India.

Hindustan shipyard Limited is the pioneer ship building industry in India. It is located on the east coast on 83.17’E latitude,73.41’N latitude. It is one of the prestigious industries in Visakhapatnam.HSL is the part of the natural harbour of Visakhapatnam port and naval Dockyard mating with it.

Dr. BABU RAJENDRA PRASAD, The president of India National Congress laid the foundation stone on 21st June 1941 for Scindia Steam Navigation at Visakhapatnam. Mr. Walchand Hirachand Scindia was the founder of Shipyard.

In 1947 the Government sought the advice of French Ship building Expert on the development of Lf to ship building in India would be fully development at Visakhapatnam .In 1949, there were 4000 men employed and 9 British engineer including Mr. Compher (the chief Manager of shipyard). In march 1950, Government with the formation of Eastern Shipping,Corporation entered the field of shipping .It was a joint venture with Government holding 74% of the capital and Scindia 26% of the capital. Scindia Steam Navigation Company (SSNC) was established at the present place of HSL later it was taken over by late Sri Walchand Hirachand, who opened a boat building Company with the collaboration of M/S .Sir Alexander & partners consulting engineers in U.K. The keel of the ship names “JALA USHA’’ was launched on 14 th March 1948 by late Pandit Jawaharlal Nehru our first PM.

1.1.2) Background:

The shipyard has built and delivered so far 137 ship aggregating over 1.27 million DWT. The shipyard has built big ships, small crafts, tugs, dredges, naval vessels, passenger ships, training ship, drill ship, off shore patrol support-cum-stand by vessels etc. of different designs for owners.HSL has undergrone modernization at a coast of approximately 100 crores. The shipyard is at present capable of building bulk carriers up to 80,000 DWT.HSL with expertise skill ,sound technology and a host of hull engineering back up facilities also offers excellence ship repairs

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and dry dock services.The recent orders were MOT, Research vessels, A&N administration for barges,utility boards. Tour ships of 30,000 DWT cargo’s for GEMI and acquiring repairs for Indian Navy of INS Sindukranti division. Now, one of the main ship building industries in India is going to emerge into Indian security forces for Indian Navy Wing as efficient work and faster outputs. HSL is awarded as ISO-9001 certified industry by LLOYD’s register of quality assurance (LRQA) London for construction.

1.1.3) Infrastructure Details:

HSL’s yard is spread over an area of 3,00,000 square meter. Workshops and facilities are systematically planned and functionally laid out to ensure unidirectional flow of material.

The steel processing facilities consists of a stock yard to hold 30,000 tones of steel modern plate and section treatment plant gas cutting machines, heavy duty presses self-elevating trucks capable of handling blocks of up to 250 tonnes and large pre-fabrication shops with overheard travelling cranes of adequate capacity.

The hull construction facility includes a modern covered building dock and three shipways. Cutting, wedding and assembly of steel to any specification are handled with care and accuracy by skilled operation, with are continuously trained to upgrade their skills.

The long out fitting quay is equipped with attendant self contained services and facilities i.e. hull fitting, engineering and electrical shops.

1.1.4) Principle of a Ship:

Any body that is lighter floats in the water. The principle is that when a body floats in water it displaces certain amount of water. The weight of which is equal to the weight of the floating body. By this principal ship was made of material heavier than water such as steel float on water. The Discovery of principal was made by Archimedes, the floating body should have property that if it is slightly displaced from its position of rest it must come back to that position of. Then it is said to be stable.

1.1.5) QUALITY:

Accreditation from Llods and Indian Register of shipping signify quality systems at HSL. With all facilities for Mechanical testing, Paint testing, NDT etc, HSL is poised for total Quality Management with accreditation for ISO-9000 on the threshold.

1.1.6) THE DESIGN CAPABILITY:

A remarkable achievement in the field ship design is the development of “HS-Standard flexible design” acclaimed for its excellence for its Hydrodynamic characteristics by HSVA ship model testing tank established at Hamburg ,Germanys.Seven, 27000WT bulk carriers of this design

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were built for various costumers. HSL’s design capability embraces a wide spectrum of general and special purpose vessels like medium size bulk carriers up to 70,000 DWT, Product tankers, container vessels, dredgers, passengers vessels, survey vessels, etc. it is backed up by latest CAD/CAM software a part from AUTOKON with independent work stations.

1.1.7) THE OFFSHORE PLATEFORMS:

HSL has emerged as one of the leading manufactures of Offshore Oil/Gas production platforms providing advanced technologies and up-to-date facilities. HSL’s offshore facility is geared to take on offshore projects on turn key basis covering design, procurement, fabrication, load out and instillation.Its expertise and quality standard are world class. Over twenty offshore structures fabricated in HSL’s exclusive yard are in operation at Bombay High, Southern and Eastern regions of India.

1.1.8) THE INDUSTRIAL STRCTURES AND OTHER DIVERSIFIED AREAS:

With accredited experience and technology absorbed through Shipbuilding, Ship repairs and Offshore platforms coupled with skilled manpower and modern facilities. HSL’s business activities are now being large diversified into the manufacture of large scale plants and structure such as plants and equipments, bridge girders and other steel structures. HSL also offers consultancy services for design, training, port development etc.

1.1.9) MODERNISATION:

To enable HSL to serve the growing needs of maritime industry a massive expansion modernization program at a cost of 80 corers was undertaken during 1981-86 with technical consultation from M/s Livescy & Henderson. UK and M/s Seadrec, Scotland. At present the yard is capable of about 1,30,000 dwt constructing 7 ships per annum with its modern equipments and along with other infrastructure facilities.

THE OBJECTIVES OF MODERNIZATION AND EXPANSION ARE AS FOLLOWS:

a) To achieve an output of 6 to 7 1/2 ships amounting to about 1,30,000 DWT per annum.

b) To increase the through out of steel to around 30,000tonne per annum.c) To achieve substance reduction in the shipyard cycle time.d) To reduce coast of construction.e) To update Technology .f) To eliminate presents constraints limitations and facilities building of bigger vessels

upto 45,000 DWT.

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1.2) THE ORGANISATION

Hindustan Shipyard Ltd, A public sector understanding under the administrative control of ministry of Shipyard Govt. of India.

HSL has following divisions:

Ship building divisions Ship repair divisions Retrofit divisions Offshore platform division Structural fabrication division

1.2.1) SHIPBUILDING DIVISIONS:

Capacity to construct vessels up to 50,000tonnes DWT. Two slipways (164*24m) have capacity for construction of vessels up to 30,000tonnes DWT One slipway (140*22.7m) for small crafts. Building Dock (247*53*11.25m) has capacity up to 50,000tonnes dead weight.

1.2.2) SHIP REPAIR DIVISION:It has the following facilities

Dry dock (244*38*11.6m): up to 57,000tonnes DWT Wet basin has the capacity to accommodate for repair it’s afloat .HSL’s repair ship development has accomplished maintenance & repair jobs on various variety of naval vessels including submarines, merchant ships and oil rigs.

1.2.3) OFFSHORE PLATFORM DIVISION:It has been engaged in the constructions of platform, jackets and other related structure. It has well established and experienced production organization with adequate facilities and is supported by necessary expertise divisions of.

Planning Purchase

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Production Q.A&Q.C

1.2.4) STUCTURAL FABRICATION DIVISION:

HSL has diversified its activities into industries structures of:

Railway bridge girders. Pipes of the flow out of dredged materials. Steel structure construction for process plants.

1.2.5) ORGANISATION STRUCTURE:

A well defined organization with horizontal and vertical linkage taken care of all activities, operations functions of the HINDUSTAN SHIPYARD. Senior management persons in the ranks of executive directors, General Managers, Deputy Managers and Chief Manager placed in change of various groups and divisions, the objective behind the divisionalisation is to make to heads more accountable and responsible for their decision as well as to raise the output of each team group under their control divisions.

1.3) SHIP BUILDING MEHODOLOGY

The construction activities of the ship fall into categories namely, Steel complex and Outfit complex. The major activities of the Steel complex are processing of steel plates assembly of plates and elements into fully welded panels, erections alignment and full welding of these panels on building berths as complete Hull. Survey, pressure tests and launching etc. In the outfit complex installation of main and auxiliary machinery, piping system ventilation, electrical, communication system, accommodation works, work survey, tests and trails of equipments dock trails, sea trails and delivery to the owners. After the design and drawing are complete ship’s hull form is screwed on the mould loft wooden floor to the scale development of critical shapes are done. Wooden templates and markups are made to full size to process the element of the ship’s hull

Certain elements are drawn on films to 1:10 scale in mini loft drawings officers nesting’s elements thus drawn to 1:10 scale on films are used for cutting elements on electronic tracer type automatic gas cutting machine to full size. The hull processing shop having a floor 13,700 Sq.mt has four bays with 10Tand 5T capacities electrical operated over head travelling cranes fitted with magnet beam. Steel plates and sections from steel stock yard are fed to these bays though conveyer system via magnets (Captivator, Hydro leveler and Driver) mechanic shot blasting machine and sprayed with primer. The shop is equipped with number of gas cutting machine

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most sophisticated among them being Computer Numerical Control (CNC) flame cutting machines which cuts simultaneously 4 off pieces from 1/10 scale drawing prepared on special paper in mini loft drawing office to full size. Other elements marked on the Steel plates using the wooden templates prepared in mould loft and cut in other gas cutting machine. There are Hydraulic presses with various capacities and up to maximum 2000tones forming the plates. Rolling machines, cold frame bending machines, shearing machines, cambering machines, straightening machines, plate preparation plate, section preparation plant etc. are the important machines, in the shop, there are assembly shops. One of which is 194.5 27 m and is intended for the assembly of panels up to a maximum weight of 45 tones and fitted with one number 45T on and 3 No’s 10Ton each electrically operated over head travelling cranes at two levels. The shop is installed with 80 ton & 40 ton electrically operated over head traveling cranes. The addition to assembly of peak panels, air turning and compounding of units up to 100-150 tons are done in the shop. Welding is done by automatic and semiautomatic welding equipment in addition to manual welding.

The elements proceeded in the Hull processing shop and Assembly units inspected for their workmanship of the steel complex, dimensional accuracy by the quality control on the steel complex and presented to the classification society surveyor for inspection because they dispatched to block storage for Assembly Erection.

The Pre Fabrication units (called panels/blocks) are transported to storage area./berth from the assembly shop by 100 Ton &150 Ton capacity self elevation & propelling low bed trailers. They can load and unload themselves without the help of any cranes. Thus the fabrication panels can be transported without much difficulty.

HSL has three building berth /slipways for construction of ships up to maximum 30,000DWT. These berths are served by 5 no’s of heavy duty cranes of 35 Tons to 100 Tons. Capacity of level fluffing and hammer headtype cranes. Each assembly a crow type staging are provided inside and outside the ship under construction on berth. It is surveyed by the surveyors of classification society in various stages ensuring quality of the structure and weld joints including Non Destructive Testing .The ship tanks in addition to dry surveyors are pressure tested with air and water. After the assembly & inspection, the ship outside hull portion is painted scheme. The launching is being done at present by conventions method with 2 launching ways consisting of timber standing, sliding ways, base and slip coast grease applied in between.

For the purpose of fitting out the ship after launching, the shipyard has an Out fitting quality of 1500 ft. Long and capable of accommodating 3 pioneer of 21500 DWT. The jetty has a 125 ton fixed hammer head crane and four level bluffing cranes of 50ton, 10 ton and 5 ton capacity each. Along the length of the jetty, the out fitting infrastructures like Engineering Department, Plumbing sheet metal, electrical, carpentry, rigging and black smith. Galvanizing and painting

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departments and shops are situated. All these departments and their shops as well equipped with good number of machines for the fast and efficient working.

1.3.1) TRANSPORTATION OF PANELS/UNITS:

There are two self elevating and propelling low bed trailers (KAMAG make from Germany). One of 100 T and other of 150T for transporting the units from Prefabricate shops to slip ways jetty and building docks. These trailers are provided with most sophisticated Electronic multi layer Hydraulic Steering gear system. A coupling arrangement is provided for random operation of both the trailers for transporting units of order of 200T to 250T with one operator from 150 T trailer.

1.3.2) SHIP BUILDING BERTHS:

These are 3 slipways / building available for construction of vessels 30000DWT.

AREA:Berth No. 11 140 M long *22.7M wide.Berth No. 111 185 M long *25 M wide.Berth No. 1v 185 M long * 25 M wide.

1.3.3) TERMINOLOGY USED IN SHIPYARD:

Ship: A ship may be regarded as hollow structure to float on water capable of transporting goods from one place to another across the surface of water.

Hull: The body of the ship, the comprising shell plating, bulk heads tube.

Keel: The back of the ship, the principle fore and after member that connects the stern and stern tube.

Rudder: Fitting hinged to stern frame and used for steering the ship.

Propeller: A rotating device that drives the ship through the water. It consists of three or

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four blades, resembling those of an electric fan, sometimes called screw or wheel.

Aperture: The space provided between the rudder and the stern frame for the propeller.

Port: The left hand side of the ship, looking forward standing at the centre line of the ship.

Starboard: The right hand side of the ship looking forward standing at the centre line of the ship.

Steargear: An aperture to control the rudder while steering the vessel.

Drydock: A dock into which a vessels is floated , the water is removed to allow work to be done at the bottom.

Knot: A speed of the vessel measured in nautical miles per hour (1 knot=1.852 m/s).

Propulsion: An arrangement of the main engine, propeller shafts coupled to the propeller in the propulsion system.

Sea Keeping: The required property of a sea going ship or to keep in straight direction movement, the part played by the rudder is called maneuverability of the ship.

Anchoring: Keep the ship in equilibrium condition we use anchors which is termed as anchoring.

Retrofitting: Retrofitting is refitting activity of damaged portions of the ship.

DWT: DWT is dead weight in tons including hull, machinery, outfitting equipment, crew and cargo

Tugs: Tugs are small size tractor size ships used for pushing of big ships.

Floating Cranes: Cranes mounted on small ship used for loading and unloading operation in the sea.

Draught: It is the immersed depth in the sea water denoted as T measured in meters.

VCG: Vertical centre of gravity of ship measured from mid ship in meters.

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LCG: Longitudinal centre of gravity of ship measured from mid ship in meters.

CL: It is the abbreviation for the centre line of the ship.Bow Thruster: It is a small type propeller for easy turning of ship and arranged as forward zone.

Aft And Ford: Back end of the ship is called aft end. Front end of the ship is called forward end.

Drag And Lift Force: The component off the total force in the direction of the motion is called Drag. The component of the total force in the direction perpendicular to the motion is called lift.

Ahead And Astern: The forward travel of the ship is called Ahead condition and the backward travel of the ship is called Astern condition.

Superstructure: The housing and the structure above main dock is called superstructure. This arrangement meant for crew accommodation and officers such as steering , ratio rooms etc.

Camber : a transverse curvature or crown to the decks for the purpose of draining rain or sea water to sides

Hatch: Opening in the deck for the passage of

Cargo into the hull is known as hatch.

Bracket: A triangular piece of plate used to

connect rigidly two or more parts that meet at

some angle with one and other. For example a

deck beam connected to frame and frame to

margin plate.

Beam: It is a transverse horizontal member supporting a deck or a flat extreme width of deck.

Coaming: The vertical boundary of the hatch or skylight or for any other openings is known as coaming

1.3.4) Materials used in ship building:

1) Wood2) Iron3) Wrought iron4) Steel

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5) Copper6) Bronze(gun metal)7) Brass8) Phosphor bronze9) Aluminium alloys

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1)1.4) SHIP

1.4.1) Ship-Vessel-Boat

From a ship builder’s point of view, a ship is in any way a structure of metal, usually steel or wood that will float in water and carry a load i.e. a large sea going vessel, suitable for deep water navigation.

A ship whose main power is steam is termed as steam ship or steamer. A ship propelled by diesel is known as motor ship.

The term vessel is also used in similar meaning. Vessels used for purpose of transportation but provided by no means of propulsion are called barges. These are usually moved by towing.

The term boat means any water craft. Generally it indicates a small open vessel, moved by oars or pedals, but often by sail or some power mechanism.

1.4.2) Type of Ships

1) Cargo ships 2) Three islands type ships 3) Shelter Deck (open and closed)4) Gram Cargo Ship 5) Passenger Ship 6) Tankers 7) Tugs 8) Other types

1.4.3) Three Linear Motions 1) Surge (x-axis) , Lengthwise

Propulsion and drag act along this axis. Surfing is an example of surge caused by a wave 2) Sway (y-axis ) , sideways

Generally a minor movement in a large vessel caused due to wave and wind loads 3) Heave (z-axis) , up and down

The wave motion causing the whole ship to rise and fall

1.4.4) Three Rotation Motion 1) Roll (Around x)

The most significant stability criterion – capsize. It is caused by waves, wind and can be induced by yaw

2) Pitch (Around y)

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It is a rocking motion between bow and stern of the ship. It is mostly wave induced.3) Yaw (Around z)

This is what the rudder is supported to do. Rudder corrections for course keeping illustrate that wind and waves can cause yawing motions

1.4.5) Principle Dimensions of the ship

i. Shell

The Principle function of the shell is to act as a watertight skin. It also gives strength to the

construction of intermediate parts. Shape or contour, Transverses are not all the same

distance apart ;amidships, where there is the greatest strain, they are spaced more closely .

The transverses are cut or notched where they connect on the shell, to allow the longitudinal

to pass through. They are strengthened by clips at these pointes.

ii. Longitudinal

These run force and aft from bulkhead to bulkhead, except in the shelter and upper deck,

where some are broken by hatch interference. They give strength and rigidity to the

framework and shell. They are connected and welded at the flange of the channel to the shell

or deck.

iii. Bulkheads

The vertical partitions that divide the hull into separate compartments are called bulkheads

are watertight. These water-tight bulkheads are so arranged that in case of accident at sea,

water would be confined bulkhead to one compartment only. The collision bulkhead in the

front end is constructed to withstand heavy strain and shock in case the bow is staved in.

iv. Double Bottom

The double bottom extends from the flat keel to the tank top. It is strongly constructed and is

water tight so that in case of accident causing an inrush of water into the double bottom, the

ship would still be able to keep afloat. The principal parts of the double bottom are the flat

keel, vertical keel, floors, intercostals girders, bilge, brackets, tank top, longitudinal,

bounding bars and angle clip.

v. Lines Drawing

It is a plan showing, in three views, the moulded surface of the vessels.

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vi. Moulded Surface

It is the inside of the skin or plating in a ship. The moulded surface has no thickness, and is

fair and smooth. Actually, when the ship has been built, the thickness of the plating will

extend outside of the moulded surface. “outside “ strakes of plating do not They get their

name from the fact that shell “frames “ or ribs usually are made to this shape and installed

transversely in the ship. The lines drawing consists of three views; a half-breath plan, a

profile view, and a body plan. These views each show only one side of the ship (usually, the

port side), because all dimensions for the starboard are equal and to the opposite ‘hand’; that

is, ship is symmetrical about the centre line.

vii. Profile

It is a view showing at the moulded lines from starboard to port. The waterlines and the

frame lines are straight when observed from this direction. The deck line or “Sheer “curve

shows up clearly in the profile, Which for this reason is sometimes called the sheer plan.

viii. Body Plan

It is a view showing the shapes of the frame lines. The body plan is made in two parts. The

right-hand part is a view looking directly aft at the force port side of moulded surface,

while the left-hand part is a view looking directly forward at the after half of the port

side. This arrangement prevents the frame lines at the after end from obliterating or fouling

the frame lines at the forward end. This view shows buttocks and waterlines straight, while

the frame lines appear in their true shape.

ix. Half-breadth or waterline plan

It is a view looking down on the moulded surface. Here the frame lines and buttocks appear

straight, while the waterlines show their true shape.

x. Load Waterline(LWL)

The waterline at which the ship will float when loaded to its designed draft .

xi. Forward perpendicular (FP)

It is a vertical lines at the point where the load waterlines crosses the for most part of the

moulded surface.

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xii. Freeboard (moulded)

It is the difference between the moulded depth and the moulded draft (it is the height of the

side of the vessels which is above the water when she floats at her load the water when she

floats at her load water lines).

xiii. Camber

It is the curvature of the deck transversely. It is measured by the difference in height

xiv. Transverses

These are the ribs or frames of the ship and when placed in position gives the principle touch

the moulded surface if they have a liner against the shell frame .The heel of each shell frame

is in this moulded surface (unless joggled). It should be remembered that this moulded

surface is not an actual part of the ship. It is almost exactly the shape which a thin piece of

sheet rubber would take if stretched tightly over the shell frames and main deck beams with

no planning in place.

xv. Base Line

It is a straight horizontal line at or near the bottom of the moulded surface from which

vertical heights are measured . Usually , The base line is the very lowest part of the moulded

surface .

xvi. Waterline

It is the interaction of the moulded surface with a horizontal plane at a given height above the

base line . The six foot water line is exactly six feet higher than the base line

xvii. Center line

It is a straight line running from bow to steam , midway between the sides of the ship . All

transverse horizontal dimensions are taken from the centre line . The centre line as applied to

a transverse bulkhead is a vertical line in the middle of the ship .

xviii. Buttock

It is the interaction of the moulded surface with a vertical plane at a given distance from

the centerline of the ship .Buttock are shown in the profile in the lines drawing . Ship – fitters

use a buttock merely as a distance from the centerline . Thus, they have buttocks marked on

bulkheads , decks , foundation , etc. , for setting and alignment . The buttocks and the

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waterlines which are marked on the steel members for regulating and setting are usually of

some dimension expressed in even feet .

xix. Frame line

It is the intersection of the moulded surface with a vertical plane perpendicular to the

centerline (transverse plane) . Frame lines are shown in the lines drawing .

xx. After perpendicular (AP)

It is a vertical line usually at the after end of the rudder post . Of there is on rudder post ,it

usually is taken at the centre of the rudder stock .

xxi. Length between perpendiculars(LBP)

It is the distance from forward perpendicular to the after perpendicular. To the designer,this

length is very important ,since it largely depends upon the amount of power needed to

drive the ship

xxii. Length Over-All (LOA)

It is the total length of the ship from one end to the other, including bow and stern overhang.

xxiii. Mid ship Section

A transverse section exactly half way between the F. P and the A. P . Almost invariably , this

is the widest part of the ship .

xxiv. Parallel middle body

The straight part at the centre of the ship where the water lines and buttock have no curvature

that is , where all the forces and aft lines are parallel.

xxv. Dead rise

It is the rise of bottom .It is the difference in height between the base line and the point where

the straight line through the bottom flat surface intersects the vertical line through the side of

the moulded surface at its widest point .

xxvi. Depth

It is the height of the ship at the mid ship section from the base line to the moulded line of the

deck at side (underneath).

xxvii. Draft (moulded)

It is the height from the base line to the load water line between the deck at centre at side .

xxviii. Tumble Home

The amount the top of the side shell slopes back toward the centerline between the point of

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widest breadth and the deck at side.

2. HULL SHOP LAYOUT

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The plates and sections brought from the hull are assembled here by welding process with different welding techniques . In Hindustan Shipyard Limited (HSL ) the welding processes used are

1) Shielded metal arc welding 2) Gas metal arc welding 3) Submerged arc welding

2.1.5) Hull Shop Process:The hull shop process can be sequenced as shown below.

Hull shop process

Generally steel drawing office will allocate the material as per the schedule. The steel stores will issue the material in requisition of Hull shop.

All plates are then mangled, shot blasted and painted. At this process is being done to prevent corrosion.

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Plate Treatment

Marking and Cutting

Bevel Cutting (Optional)

Forming

Bending Rolling Shearing

Binning

Delivery to Pre-Fabrication

Markers will mark the plates and sections with the help of templates and drawing. They will

write complete process on marking, material, type of edge preparation, forming, cutting lines,

dispatching, destination, etc.

Hull shop consists several machines for such as flame cutting machines, ignition machines, sheet

pres, 2000Ton press, joggling machine, flanging machine, Guiltione shearing machine, cold

forming or bending machine, punching machine, etc

The computer numerical control (CNC) flame cutting machines can simultaneously 4 off pieces

from 1/10 scale drawing prepared on special paper in mini loft drawing office to full size. Other

elements are marked on the steel plates using the wooden templates prepared in mould loft and

cut in other gas cutting machines.

There are Hydraulic Presses with various capacities and up to maximum 2000Tons forming

the plates. Rolling machines, cold frame bending machines, shearing machines, cambering

machines, straightening machines, plate preparation plant etc. are the important machines in the

shop which have the capacity to produce elements up to 2500Tones per month. Adjacent to

this shop, there are two assembly shops. One at which 194.5 * 27 m and is intended for the

assembly of panels up to a maximum weight of 45 Tones and fitted with one number 45Ton

and 3No’s 10Ton each electrically operated over head travelling cranes. The shop is installed

with 80 Ton & 40 Ton electrically operated over head travelling at two levels. In addition to

assembly of peak panels, air turning and compound of units up to 100-50 Tons are done in the

shop. Welding is done by automatic welding equipment in addition to manual welding.

The elements proceeded in the hull processing shop and assembly units inspected for their

workmanship of the steel complex , complex , dimensional accuracy by the quality control of

the steel complex and presented to the classification society surveyor for inspection are lore

they dispatched to block storage area or berth for assembly erection.

The pre fabrication units ( called panels /blocks ) are transported to storage tea/berth from the

assembly shop by 100 Ton & 150 Ton capacity self elevating & propelling low bed trailer on

trestles. They can load unload themselves without the help of any cranes. Thus the fabrication

panels can be transported without much difficulty.

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2.1.6) Hull Shop and its departments:

The various departments linked to hull shop are

a. Design office (DO)b. Production planning and control department (PPCD) c. Stress Stores (SS)d. Material Shop (MES)e. Pre- fabrication (PF)f. Quality control (QC) g. Inspection

a. Design Office:

For coastal nation, the ship building industry is essential for defense purpose. However, to run a

shipyard efficiently is not an easy job due to several of its characteristic. They are

1) The product (a ship) size is very large both in volume and weight and each product has

thousand of different compound.

2) The design, planning and manufacturing process overlap very significantly and the

Concept of ‘’ Teamwork’’ is therefore greatly emphasized

3) The production process is very complex and complicated with very many

interdependences with these characteristics, the method of ‘’ design for quality ‘’ and

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‘’design for manufacture’’ seem to be ideal tools for the shipbuilding industry to

maintain product quality while raising the shipyard’s efficiency.

b. Production Planning and control department:

With the program ‘’ Auto CAD’’ one can generate the complete project from the lines plans

until the ‘’Cutting files’’, one can have the possibility to make complete 3- dimensional design

of the hull for necessary presentations or to create a clearer view for the customer.

Also by digitalizing the handmade construction drawing, from paper to Auto Cad, one can

completely customize the design.

3-D Drawing of Hull

Small of larger adjustment that occur during the construction of a hull must often be clarified by

means of a construction drawing . These construction drawing can be easily made and

adjusted by Auto Cad during the inspection period of a hull, without having to call in an

extra construction of design agency.

c. Pre- fabrication Department:

The cut plates and sections are initially welded together based on drawing on drawings so as

to convert then in to pre- fabricated units (also called as blocks ) . These blocks are then

forward to erection section where actual and complete welding of them takes places and the

structure of ship starts to form

d. Steel Store :

These departments meet the requirements of Hull Shop. One issue of schedule necessary plates

are issued from the storage yard to the Hull shop. Each plate is clearly marked and tracked.

25

Every detail, such as batch number, plate number, dimensions, grade and quality are marked.

The necessary operations to be performed on the plate are also marked so that no confusion

comes While it travels trough different sections in hull shop.

e. Material shop:

This department ensure continuous supply of material to Hull shop. It is necessary to analyze the

demand and the purchase of material. Because in less demand huge amounts of material is

not required, as pilling of material is caused . During high demands, insufficient material can

lead to stoppage of work, delaying the whole shipbuilding process.

f. Quality Control:

During every and inspection various measurements will be carried out, including measuring

the length , breath of the body . material thickness will be measured will be measured and

compared with value on the construction drawing.

g. Inspection:After the painting of the plates quality control department will again look very carefully at the

thickness of the body. At the same time the planting works will be checked. The micron

thickness will be measured and compared with the values in the painting scheme.

During the construction of the body it will check if all welding seems are according

shipbuilding quality and they will , where necessary , be grinded. When the welding is

finished, the welding seams and all possible damages will be covered with the strip

coasting mentioned in the painting scheme . Of all inspection then surveyor will make well

organized reports.

26

2.2) MACHINES AND SPECIFICATIONS

BAY 1

BAY 1

In Bay 1, almost all operations are cutting operations and are performed automatically by

Machines. Plates from treatment plant are directly hauled and brought to necessary cutting

machines by Over Head EOT Cranes. The machines present in Bay 1 are CNC Plasma Arc

cutting machines and CNC Flam cutting machines.

The plates are first checked, then the drawing is fed into the CNC machines and accordingly

cutting is performed. The cut plates are then moved forward for manual cutting where small

cutting operations are done such as chamfering. Manual cutting is done for some required

designs only.

The completed cut plates are stored in the binning and transferred to pre-fabrication section

whenever required.

Inspection is done after every operation is performed. Unless confirmed that the plates meets

necessary standards, it is not moved forward to the next operation.

27

Plasma cutting machine Binning

Gas cutting machine(x2)

Bevel Cutting 300 T

E

OT

Cran

e 10

T

Double V

H

ook

Cran

e 10

T

2.2.1) PLASMA ARC CUTTING MACHINE:

Specifications:

Thickness capacity 5 mm to 40 mm

Plate width 3250 mm

Skid Area 50 m x 4.5 m

Torch 1 no

Marking Pattern Powder marking

Power supply 50Hz, 3 phase,400V

Coolant Kjellfrost

Mass 534 kg

Ignition Pilot arc ignition

Efficiency 0.9

28

2.2.2) CNC FLAME CUTTING MACHINE:

Specifications:Number of machines : 2 no

Make : M S Gresham, West Germany

Type : Omnimat

Main structure : Portal type

Driving system : both sided driver

Operation mode : optical 1:1 and 1:10 and NC tape

NC unit : MG 12 SG

Effective cutting length : 1400 mm

Effective cutting width : 2 x 3650 mm

Cutting thickness : 6 to 300 mm

Travel fast speed : 6m/min

Rail span : 8800 mm

Number of torches : 4 bevel cutting = 2 high speed

Cutting : Straight line

Apparatus for vertical : automatic height

29

Location : sensor pneumatic operated

2.2.3) OVER HEAD MAGNETIC CRANES(COMMON TO ALL BAYS) :

Specifications:

Safe working load: 10 Tons

Magnetic lifting capacity: 5 Tons

30

2.3) MACHINES AND SPECIFICATIONS

BAY 2

BAY 2

In Bay 2 the material flow is same as that of Bay 1. Here the operations performed are cutting,

bending and rolling. There are 3 Gas cutting machines for cutting operations, a 2000 Ton and

800 Ton press for rolling and bending operations.

The plates from the plate treatment plant are brought over by over head magnetic cranes. Though

the cutting operations are done automatically, the bending operations are done manually. In

bending straight plates are cut into required shapes and then pressed in pressing machines. The

plates are pressed gradually until the required curvature is obtained. While one operator operates

the press other operator looks on the bending and checks the required curvature with pre

designed templates.

The cut and bent parts then stored in binning area and transferred to pre-fabrication section

whenever required.

Inspection is done after every operation is performed. Unless confirmed that the plat meets

necessary standards, it is not moved forward to the next operation.

31

storage Convert loft marking

2000 T Half rolling

800 T knuckles

250 T Rolling

Gas cutting bars Pug machine

Rolling machine

EO

T C

rane

10

T

2.3.1) VARIOSEC-AUXILLARY PORTAL:

Specifications:

Type :SH 8800

Length of the track :60m

Gauge :8.8mts

Working width :2x3.65m

Track level :500m

Cutting table level :700mm

Wt.of the machine without track :HAPO 3440KG, HIPO1=1180KG,HIPO2=1180KG

Rate of speed :75,250mm

supply voltage :3*220v

connection power :3kva

Material cutting thickness :3 to 100mm

Torches :M/S Brerer/ Torch732/110,Vadura 1210 A,

Acetylene

Nozzles :vadura 1210 A

Connection power : 3 KVA

Input : 220V,50 Hz, 1KVA

32

2.3.2) 2000 TONS HYDRAULIC PRESS:

This machine is for making flange and semi circular sections

Specifications:

Plant no :1426

Equipment :2000 Tons hydraulic press

Machine no. :186-0-83

Suppliers : M/S HUGH SMITH

Type :2000 Tons Hydraulic Rolling And Flanging Press

Power Of The Motor : 30 HP

Pressing speed : 6.7 mm/s

Working press : 5000 psi

Approach speed : 75 mm/s

Return speed : 95 mm/s

Approx press speed : 7 mm/s

Weight of press : 40 T

Length of stroke : 224 mm

Throat clearance diameter :320 mm

33

2.3.3) 800 TON HEAD FLANGING PRESS:

Specifications:

Plant no. :786

Equipment :800T BULK HEAD FLANGING PRESS

Machine no. :C25927

Suppliers :M/S HUGH SMITH AND CO.GLASGOW

Capacity :10Mx800 Tons

Main ram :19 ½ mm

Length of each die : 79 ½ mm

Stroke :145/8

No. of dies :5

Total flanging length :260mm

34

2.4) MACHINES AND SPECIFICATIONS BAY 3

In Bay 3 the main operation performed is bevel cutting. Also other operations are performed too

which are cutting, bending and rolling. Cutting is done by plasma cutting machine. This cutting

machine is newer and latest version of the plasma cutting machine than the machine present in

Bay 1. On this machine cutting is performed more easily and fastly.

Bending, shearing and rolling operations are performed by 500 Ton press, hydraulic shearing

machine and pressing machines.

Bevel cutting is done on pug machine. The edge of the plate is given a bevel cut (a chamfering

operation to the edge of plate). On the requirement the bevel cut may be both sides (SVOS) and

singular cut (SUOS).

The plates from the plate treatment are brought over by over head magnetic cranes. The required

operations are performed. The cut and bent parts are then stored in binning area and transferred

to pre-fabrication section whenever required.

Inspection is done after every operation is performed. Unless confirmed that the plate meets

necessary standards, it is not moved forward to the next operation

35

Rol

lers

EOT

Cran

es 1

0T (2

)

Binning Edge preparation 500 T

Plane cutting machine

Hydraulic jack Hydraulic shearing cutting m/c

Hoo

k Cr

ane

2.4.1) 500 TONS HYDRAULIC PRESS:

SPECIFICATIONS:

Plant no 2445Equipment 500 T Hydraulic PressMachine no MT 4608Type suppliers M/S Indian sugar & General Engg Co.LtdLoad of press 500Tons Working pressure 320 Kg/sq cmStroke 900 mmBed area 1850x1550 mmTable 1200x1550 mm Offset from main ram to main frame 1300 mmReturn load 30 TonsMain ram diameter 450Return ram diameter 160x140

36

2.4.2) Hydraulic guillotine shearing machine:

SPECIFICATIONS:

Type A.S.2550*20 Suppliers M/S Mager & Weremever Bremen, Germany Plant no 917 Equipment Hydraulic Guillotine Shearing machine Machine no 1308 Length Of The Blade 2600 mm Free space between stops 2350mm Gap in end frames 400mm Max pressure in Hydraulic system 250atm Max pressure in hold down system 90 atm pressure in return stroke 130atm capacity of accumulator 10 L capacity of oil tank 600 L weight of machine 17,700 kg Oil quality (hydrated oil) -4.50 E at 500

37

2.5) MACHINE AND SPECIFICATIONS BAY 4

BAY 4

In Bay 4 manual work is done. Here collective to all bays cutting, bending, rolling, bevel cutting

and forming operations are performed. The sequence of operations is similar to other bays but

the only difference here is that they are performed manually. The plates from the treatment plant

arrive here by over head magnetic cranes. These plates are called as sections. Mainly the parts

made here are frames, beams, pipe sections etc. firstly the section are made, labeled properly.

Then they are transferred to respective machines to perform necessary operations. The finished

products are inspected, necessary changes made and then sent directly to pre-fabrication section.

Inspection is done after every operation is performed. Unless confirmed that the plate meets

necessary standards, it is not moved forward to the next operation.

38

EOT

Cra

ne 1

0 T

Frame Bending Machine

Cambering Machine

400 T Cold Frame Bending Machine

Profile Cutting Machine

Manual Marking and Labeling Punching

Bin

ning

2.5.1) 400 Tons Hydraulic Cold Frame Bender

SPECIFICATIONS:

Plant no. 1158 Equipment 400 Ton Hydraulic Cold Frame Bender Machine no. 627022 Suppliers M/S HUGH SMITH AND CO. Bending capacity cold flat frame up to 17 inches Bending capacity cold angles up to 15"X15" and in pairs Weight 21 Tons Output Of Pump 4300cu/min Tank Capacity 150 gallons HP of the motor 40 HP Horizontal stroke 16"Forward stroke 36"/secWorking pressure 4500 psi3 clamps ram each 3"strokeClamp Pressure 4500 psiClamp Speed 0.092"/secBar speed gear 13"/secMin. bending radius out side 6",inside 10

39

3. HULL SHOP PROCESSES

40

3.1) PLATE TREATMENT LINE

Steel plates are first transferred to heat treatment line to de-scale the plates from rust, dust and impurities. It is the first step for any plate before it is used for any process in the hull shop. The De-scaling process also includes a hydro leveler and spray painting section.

In Plate treatment line steel plates are processed under various machineries to make them fit for production of ship panels. The following are the various machinery sections that are present in the plate treatment line.

41

Captivator

Hydro Leveler

Heating Chamber

Blasting Chamber

Spray Painting Section

Dry Chamber

PLATE TREATMENT LINE PROCESS LAYOUT

3.1.1) Captivator :

The steel plates from the steel storage yard are lifted onto the captivator by a magnet and placed

onto the inclined portion (the head section) of the captivator. The head section consists of three

important rollers namely free roller, magnetic roller and motorized rollers.

The plate first lands inclined onto the head section. The magnetic roller holds the plate and pulls

the plate onto the ‘hip’ section of the captivator. The free roller enables easy access of the plate

to roll while lifting off the ground. The motorized rollers push the plate towards the hydro leveler

Specifications :

Maximum plate load : 10 Tons

Maximum plate size : length 14 m, width 3.65 m

Maximum plate size : length 3.65 m, width 1.5 m

Plate thickness : Max-50 mm, min-5 mm

Hoisting speed : 8/4 m/min

Travelling speed : 90/30 m/min

Roller speed : 30 m/min

Trolley speed : 30 m/min

Number of piles : 3

Max height of piles : 600 mm

Main voltage : 3x440 V, 50Hz

Pilot voltage : 220 V, 50Hz

Power supply : cast on cable drums automatic operation is controlled

through Programming Looping Systems(PLS)

3.1.2) Hydro-Leveler :

A Hydro-Leveler is a 80 Ton capacity hydraulic powdered machine to level the plates and free them from

any curves, bends and distortions so as to make the plate perfectly flat.

42

It consists of 5 rollers, 2 at the bottom and 3 at the top as shown in figure.

Top rollers (press)

Bottom rollers Plate movement

The bottom rollers can rotate clockwise or anti-clockwise such that the plate travels in left or

right direction. The top rollers apply pressure onto the plates while the plate moves along the

bottom rollers making them flat. The minimum width of the plates that can pass through the

rollers is 6 mm and max width is 21 mm. Though higher thickness plates can pass through these

rollers (upto50 mm) the plates cannot be leveled. Plates with large thickness need not be leveled

because the disorientation can be neglected when compared to thickness

Specifications :

Hydraulic pressure : 315 bars and 100 bars

Hydraulic medium : mineral oil

Test pressure Centre beam : 395 bars

Working pressure centre beam : 100 bars

Test pressure : 125 bars

Working pressure : 315 bars

Test pressure : 395/395 bars

Down/up speed : 9.1 m/min

3.1.3) Heat chamber:

43

The plates are then moved into a heating chamber where they are heated so as to remove moisture content

and other liquid material such as oils from the surface of the plates. Moisture causes plates to rust and

corrode and makes the plate useless. It has a capacity of 96 KW and facility with manual operation.

3.1.4) Blasting chamber:

Blasting is an important step in heat treatment line. It removes all the impurities on the surface and

makes the surface clean and pure. It consists of 8 roto blasts, four on top and four on bottom. Small

spherical grits made of mild steel are made to incident on plates with great force and high velocity. This

will result in the removal of rust and mill scales. The grit is fed from overhead tank then into a motor

(impeller). It has axial entry and radial exit. Its equipment is used for the purpose of removal of rust and

dust particles from the plate.

Wet plate subjected to blasting will cause the formation of grit material, which is undesirable

so in order to prevent the formation of grit material the plates are usually passed through heating

template before entering the blasting chamber.Grits are recycled until they become powder

blasting process is said to be completed successfully if the plate has asilver white colored looks

otherwise the plate is sent back and the blasting process is repeated.

44

Specifications :Material : mild steel to be dry and oil free

Maximum plate thickness : 5 to 50 mm

Maximum plate width : 3.65 m

Maximum conveyor load : 1000 kg/linear meter

Maximum working length : 2500 mm

No of roto blast wheels/power : 8/37 KW

Separation type : air wash

Separation size : 7 inches

Ventilation requirement : 41,650 m3/hr

3.1.5) Spray painting unit :

The blast is equipped with micro computer which enables paint spray in both directions i.e. top

and bottomafter cleaning. This has 8 no’s airless spray film thickness of 25 microns can be

achieved. The treatment line is also provided with the pre heater before shot blasting and drying

chambers after painting. The grits that are spherical in shape while removing rust and scale may

also form some indentation on the plate. The indentation formed on the plate is covered during

spray painting. Painting is done to avoid corrosion of plates.using two nozzles on the top and two

on bottom, spray painting is done

Paint to nozzle issupplied by pump. There are 2 pumps one will supply paint to the top nozzle

and other will supply to the bottom nozzle. The paint used is zinc rich prime (costlier, long life,

9-12 months), zinc silicate primer (cheap, short life, 6 months). After spray painting the plate is

fed to the drying chamber where the plate gets dried , the smell of paint is also removed and it is

made to pass into the atmosphere through chimney. It is used to paint the plate in perfection

without wasting the paint by controlling electronically.

45

Specifications :

Type : air less

Number of spray guns : 4

Number of paint pumps : 2

Speed of spray guns 1.5 m/s

3.2) PLASMA ARC CUTTING MACHINE

Plasma is defined as a gas having atoms and molecules which are partly split into ions and

electrons therefore having high electrical conductivity Plasma cutting is a process that is used to

cut steel and other metals of different thicknesses (or sometimes other materials) using a plasma

torch. In this process, an inert gas (in some units, compressed air)becomes heated up extremely

and blown at high speed out of a nozzle; at the same time an electrical arc is formed through that

gas from the nozzle to the surface being cut, turning some of that gas to plasma. The plasma is

sufficiently hot to melt the metal being cut and moves sufficiently fast to blow molten metal

away from the cut.

46

The plasma are hereby is transformed from the cathode, installed in the plasma torch and

conducted the negative pole of plasma power source to the work piece(transferred arc). The

Plasma Cutting is a technology for cutting of electrically conductive metals, like constructional

steels ,stainless steels, aluminum, copper etc. it is suitable profile template and bevel cutting. So

plates, tubes, profiles, formed and casted parts can be cut or worked.

3.2.1) Plasma Cutting without Secondary Gas:

47

contents  

3.2.1) Plasma Cutting witout SecondaryGas3.2.2) Swirl Gas Technology3.2.3) CNC Cutting methods3.2.4) Coolant3.2.5) Features and Advantages3.2.6) Applications3.2.7) Safety3.2.8) New technology3.2.9) NC Programming

Freehand cut of a thick steel plate

The HF Contact type uses a high-frequency, high-voltage spark to ionise the air through the torch head and initiate an arc. These require the torch to be in contact with the job material when starting, and so are not suitable for applications involving CNC cutting.

The Pilot Arc type uses a two cycle approach to producing plasma, avoiding the need for initial contact. First, a high-voltage, low current circuits used to initialize a very small high-intensity spark within the torch body, thereby generating a small pocket of plasma gas. This is referred to as the Pilot arc .The pilot arc has a return electrical path built into the torch head. The pilot arc will maintain itself until it is brought into proximity of the workpiece where it ignites the main plasma cutting arc. Plasma arcs are extremely hot and are in the range of 25,000 °C (45,000 °F).

Plasma is an effective means of cutting thin and thick materials alike. Hand-held torches can usually cut up to 2 in (48 mm) thick steel plate, and stronger computer-controlled torches can cut steel up to 6 inches (150 mm) thick. Since plasma cutters produce a very hot and much localized "cone" to cut with, they are extremely useful for cutting sheet metal in curved or angled shapes.

3.2.2) Plasma Cutting with Secondary Gas(Swirl Gas Technology):

Plasma torches for the secondary gas technology are using a swirl gas for shielding the plasma arc from the atmosphere with the conventional Dry plasma cutting. The plasma arc is directly transferred from the nozzle to the work piece. Spatter and upcoming material can lead to double arcing and to reduce nozzle life and poor cutting quality. Plasma torches using the swirl gas cap and the surrounding swirl against the upcoming material, especially when cutting starts by piercing. Flow rate and composition of the swirl gas can be optimized to obtain best cutting results on different materials.

It shows the principle of the swirl gas technology in comparison to conventional dry plasma cutting. The underwater cutting process reduces the pollution of the environment, the noise level of the process and the light radiation considerably in comparison to the dry cutting. The distortion of the cutting material is very low. Since the consumption of electrical energy is higher.

One of the advantages of the swirl gas technology is the fact that plasma torch suitable for the dry cutting and the underwater cutting as well without any adaption to the torch. Furthermore the cutting process grants highest stability, ensuring optimum cutting quality for both dry and underwater.

48

3.2.3) CNC cutting methods:Plasma cutters have also been used in CNC (computer numerically controlled) machinery. Manufacturers build CNC cutting tables, some with the cutter built in to the table. The idea behind CNC tables is to allow a computer to control the torch head making clean sharp cuts. Modern CNC plasma equipment is capable of multi-axis cutting of thick material, allowing opportunities for complex welding seams on CNC welding equipment that is not possible otherwise.

Plasma cutting with a CNC machine Plasma cutting with a tilting head

For thinner material cutting, plasma cutting is being progressively replaced by laser cutting, due mainly to the laser cutter's superior hole-cutting abilities.

Software will process information on ductwork and create flat patterns to be cut on the cutting table by the plasma torch. This technology has enormously increased productivity within the industry .

In recent years there has been even more development in the area of CNC Plasma Cutting Machinery. Traditionally the machines' cutting tables were horizontal but now due to further research and development Vertical CNC Plasma Cutting Machines are available. This advancement provides a machine with a small footprint, increased flexibility, optimum safety, faster operation.

3.2.4) Coolant:Kjellberg finsterwalde is used for all liquid cooled units and torches. The new coolant Kjellfrost, is acting additionally as antifreeze. It is nearly a colorless liquid. It contains anodic and cathodic inhibitors. They are protecting in a very efficient way all the components of the circuits against corrosion ,even when components are mixed materials such as steel, copper, and copper alloys. The coolant should be changed once in a year.

49

3.2.5) Features and Advantages:The application of fine process principle generates extremely high energy densities and offers numerous technological advantages. These include:

Double Straight effect Narrow cutting joints Low material loss Low heat input Low distortion High cutting speed Excellent Cutting Flow

Further technological advantages are gained from the secondary gas technology in dry and under water plasma cutting by utilizing XL-Life-System for plasma cutting with oxygen.

3.2.6) Applications:The plasma arc cutting can be used everywhere where Dry Plasma Cutting and Under Water cutting are performed.All plasma torches are suitable for flying start and piercing. Straight, bevel, contour and position cuts can be carried out as well as fusion drilling and gouging of welding seams. Semi finished products such as sheet metal, pipes, profiles, forged and formed parts, sheet stacks, scrap products and castings can be thermally separated.

3.3.7) Safety:Proper eye protection such as welding goggles and face shields are needed to prevent eye damage called Arc eye as well as damage from debris.

3.2.8) New Technology:

50

Hand held plasma cutter High performance cut

In the past decade plasma torch manufacturers have engineered new models with a smaller nozzle and a thinner plasma arc. This allows near-laser precision on plasma cut edges. Several manufacturers have combined precision CNC control with these torches to allow fabricators to produce parts that require little or no finishing.

3.2.9) N.C PROGRAMMING

Program Aim

An NC program to mark a 500 x 500 mm marking line(yellow) and perform cutting on 1000 x 1000 mm(red) such that both the operations are concentric as shown in figure.

Program:

%

01500(square.ess)

G92X0.YO.

G90

G00X260.00Y260.00

M27

M23

M00

F15000

M210

G01X760.00Y260.00

G01X760.00Y760.00

G01X260.00Y760.00

51

G01X260.00Y260.00

M22

M28

M24

M00

G00X10.00Y10.00

G42D17

M17

F2300

G01X1010.00Y10.00

G01X1010.00Y1010.00

G01X10.00Y1010.00

G01X10.00Y10.00

M18

G40

G0OXO.OOYO.OO

M30

%

Program Description:

01500(square.ess) : program file name

G92 : Reference point (00)

G90 : Absolute mode

G00 : Rapid movement

M27 : Marking torch off-set ON

M23 : Preheat On

M00 : machine stop

F : feed

M21 : marking on

G01 : linear interpolation to specified coordinate

M22 : marking off

M28, m24 : m28-priority torch off set off, m24-pre heat off

G42 : kerf on

G40 : kerf off

52

M17 : cutting start

M18 : cutting stop

M30 : program stop end

Initially the torch is set reference point (0,0) by G92 command. Then measurement parameter is set to absolute mode (G90). This means that the exact coordinates are given for torch movement. Torch is set to reference point and a 10x10 tolerances given to as to enable cutting. Always the movement of torch is directed from inside to outside. So, first the inner marking patterns drawn. Torch is moved along the square by giving the absolute co-ordinates (260,260), (760,260), (760,760), (260, 760). The torch is set into making mode (M27), powder marking is enabled (M23). The respective feed is given by the F15000 (15000mm/min) (since it is only markingspeed set to machine’s maximum speed). Then torch is moved to theouter square for cutting. Similarto the marking pattern, cutting is also done. Here cutting torch is enabled (M17). Torch is moved along the co-ordinates (10,10), (1010,10), (1010,1010), (10,1010). Feed is set to F2300 (2300 mm/min). After the completion of program ,program stop command is given (M30).

Though the NC Commands are same for all the NC machines, torch commands and cutting commands are specified to type of machine and changes from manufacturer to manufacturer.

3.4) CNC FLAME CUTTING MACHINE

Computerized Numerically Controlled (CNC) Gas Cutting Machine:

The Painted plate from plate treatment line is transferred to CNC gas cutting machine where the

marking and cutting takes place from where it is sent to forming and fabrication department.

For cutting plates there are three methods:

3.4.1)Optical system

3.4.2)Co-ordinate system

3.4.3)CNC Numerical system

3.4.1)Optical system:

The sketch of the required shape is made on a film. The optical system mandated the

magnetically lines on the film and the required cut is obtained.

3.4.2) Co-ordinate system:

The plate is cut by manual operation that is by moving the gas cutting nozzle in X and Y

coordinates, the above two methods have certainly disadvantages and doesnot give an accurate

cut so CNC numerical systemis used which is accurate gives the high quality and high

53

production. The cutting of plate takes by passing gas through the nozzle, the distance between

the nozzle and the plate is generally 1/8th of inch.

The nozzle is selected depending on the plate thickness. Dot punch is done on the plates that

serves as marking for further more operations to be performed after which the gas cutting the

plate is transferred to forming where the plate is deformed into required shapes.

3.4.3) Numerical system

Implementation Of Cutting Technologies:

In order to cut the elements various codes are used as mentioned below:

G-code, or preparatory code or function are functions in the numerical control programming

language. The G-codes are the codes that position the tool and do the actual work, as opposed to

M-codes, that manages the machine. T for tool-related codes. S and F are tool-speed and tool-

feed and finally D-codes for tool compensation.

The programming language of Numerical Control (NC) is sometimes informally called G-code

but in actuality, G-codes are only a part of the NC-programming language that controls NC and

CNC machine tools. The term Numerical control was coined at the MIT servomechanisms

laboratory. And several versions of NC were and are still developed independently by CNC-

machine manufacturers.

There are other codes. This type codes can be thought of all registers in a computer.

X- Absolute position

Y- Absolute position

Z- Absolute position

A- position (rotary around X)

B- position (rotary around Y)

C – position (rotary around Z)

U - relative axis parallel to X

V - relative axis parallel to Y

54

W- relative axis parallel to Z

3.5) Hydraulic Guillotine shear

The machine is used for cutting sheets with thickness from 1 mm to 20 mm and width less than

3200 mm. the tensile strength of the sheet need to be cut is 4500 MPa. If the machine is used for

cutting the order tensile strength of material, the thickness of the sheet should vary

correspondingly.

55

The machine has higher productivity and is ideal sheet cutting equipment widely used in the air

craft industry, automobile industry, ship building, electrical appliances, machinery and light

industry.

Features:

The frame of machine is a welded construction with steel plate and the machine is driven by

hydraulic system, the machine working steady and reliably with low noise and easy to operate

The machine is equipped with front and back gauge and is controlled by NC system N20 and is

adjusted conveniently, accurately and reliably.

The front gauges use a gauge ruler to measure and stop to finger to positioning.

The stroke of upper beam can be adjusted steeples to improve the strokes when cutting narrow

sheets.

The safety barrier gauge is installed at the blade area of machine safety operation

Structure and working principle:

The main parts of machine are welded with steel plate with high strength and good rigidity.

Frame:

It is welded with steel plates and good rigidity. Main and auxiliary cylinder are fixed on the

frame. The supporting arms and rolling balls are mounted on the table and east to operate

Upper blade beam:

It is driven by main and auxiliary cylinder for cycle movement. To complete shearing and rake

angle of the upper blade beam is 1.50

To guarantee the quality of the cross-section of the sheet.

The beam is supported by the 3 point rolling guide way and the front pivot is spring gear to

eliminate the guide way gap

Gap adjustment mechanism:

56

The adjustable handle of the gap can be rotated to make the lever to drive the eccentric pivot and

swing to adjust the blades gap. The user can adjust it accordingly to the gauge of adjusting

handle of the machine.

Front gauge:

It is located on the work table. The gauge valve is indicated on the gauge ruler and the sliding

stop finger can be moved to desired position. It is very convenient to use the front gauge when

cutting thin sheets

Back gauge:

It is mounted on the upper blade beam and can move up and down with the upper blade beam.

The back gauge is driven by a motor whose power is 0.75 KW to move the sheet through the

gear box and screw bar. The back gauge is controlled by the NC system E20. When machine is

cutting thick sheets back gauge is very important.

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4. SUMMARY

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4.1) Synopsis

Production is performed confirming to the documents, pertinent drawing material and allocations

received from PP & PM with emphasis on the quality standards, work instructions and the

quality plan from inspection activity.

Firstly, the plates and sections are blasted and primed in preparation plant before taking up the

production. All unprimed steel plates and sections issued by steel stores are processed through

mangling, de scaling, spray painting and drying process before processing elements. Surface

condition after shot blasting and priming is checked for flaking, pitting and visual laminations

and wherever they are observed on the plates, such plates are sent back to steel stores through

NCRR for replacement and rectification. Uniformity of priming and dry film thickness are

checked and recorded by hull shop. Record of inspection is maintained on relevant inspection

record sheets for plates and sections.

Using the floppies and formats elements are generated on CNC machine. Elements are generated

on CNC machine with pertinent floppies and formats supplied BY Mini Loft (MLDO) in a

controlled manner through PP & PM second level. Checking dimensions for CNC floppies and

formats in a panel are be issued by MLDO and vitrified after processing the elements and

approximately recording at Hull shop. Using the PMC drawing the marking and cutting of

elements are carried out.

Pug gas cutting machines, variosec machines are deployed. Using the bending data supplied in

the relevant part list drawing, the templates are prepared for checking correctness of rolling and

bending after the forming of elements from both plates and sections.

Forming of elements (plates and sections) are performed and checked as per the templates

prepared on the basis of relevant data in part lists prior to checking. Records of inspection are

maintained in relevant inspection record sheets. Marking and cutting of sections are carried out

as per the relevant part list drawing. Inspections are carried out on completion of various

processes as per the quality plan and are recorded in relevant inspection records. Non-

conformances noticed, if any are reported in the relevant non-conformances report. Corrective

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actions recommended in the non-conformances report are taken and the feedback is given to

quality assurance after completion of the corrective action.

Rejected material, if any as per the resolution are identified as rejected and stored separately. The

identity of materials are maintained after blasting and priming of plates and subsequently identity

transferred to generate elements in plate. Processed elements meeting specified requirements of

that stage are dispatched to pre-fabrication department panel wise / assembly wise and to other

departments drawing wise as per the internal works order. The process elements for other

drawings are dispatched to the respective departments as per internal works order. The off cuts

generated from PM & NC is kept in Hull shop with code number as given by MES. These cut

pieces are used per the MES allocation. Accounting of these off cuts is carried out by Hull shop,

and relevant records are maintained.

4.2) CONCLUSIONS:

The total ship manufacturing process is observed while visiting HSL, Visakhapatnam and the

conclusions are

Visited Hull Manufacturing Shop, Pre Fabrication Department and Erection Department.

Identified the Plasma Arc Cutting, CNC Flame Cutting during Hull manufacturing.

The Plasma Cutting is an automatic process and its working is verified using NC codes.

Developed a computer code for cutting parts of new Hull body

By the use of the Computer Codes Plasma Cutting can be done faster and accurately.

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4.3) BIBLIOGRAPHY

4.3.1) Books and Material

1) CNC Plasma arc cutting machine, instruction manual

2) Variosec- Gas cutting machine, instruction manual

3) Lamba press(Hydraulic Guillotine shear), instruction manual

4) Hull shop department procedure and regulations

5) Hull shop manual, prepared by various managers.

4.3.2) Internet

1) Google maps

a) http://hsl.nic.in/

b) http://hsl.nic.in/aboutus

c) http://hsl.nic.in/gallery

2) Quality control shipbuilding

a) http://www.qualitycontrolshipbuilding.com/index.htm

b) http://www.qualitycontrolshipbuilding.com/international.htm

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6)

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