part 3

Rules and Regulations for the Construction and Classification of Steel Ships

Part 3General Hull Requirements

July 2011

Indian Register of ShippingPart 3 General Hull Requirements ContentsChapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 General, Definitions, Documentation Materials of Construction Principles for Scantlings and Structural Details Design Loads Longitudinal Strength Bar Keel, Stem and Sternframes Bottom Structure Side Structure Deck Structure Bulkheads Superstructures, Deckhouses and Bulwarks Openings and Closing Appliances Ventilators, Air Pipes and Discharges Rudders Anchoring and Mooring Equipment Masts and Rigging Welding Hull Inspection, Workmanship and Testing

Rules and Regulations for the Construction and Classification of Steel Ships - 2011 Page 1 of 10 ___________________________________________________________________________________

Contents

Chapter 1 : General, Definitions, DocumentationSection 1 : General 1.1 Scope 1.2 Equivalence 1.3 National and international regulations 1.4 Stability Section 3 : Documentation 1.5 Damage control plan and booklet for dry cargo and passenger ships 1.6 Protective location of fuel oil tanks 1.7 Assumptions 3.1 General 3.2 Plans for information 3.3 Additional information 3.4 Plans for approval 3.5 Plans to be kept on board Section 2 : Definitions 2.1 Principal particulars 2.2 Structural terms 2.3 Material factor

Chapter 2 : Materials of ConstructionSection 1 : General 1.1 Scope 1.2 Steel 1.3 Aluminium 3.3 Internal cathodic protection Section 2 : Use of Steel Grades 2.1 Grades of steel 2.2 Ships in normal world wide service 2.3 Structures exposed to low air temperatures 2.4 Refrigerated spaces Section 4 : Deck Covering 4.1 General 3.4 Aluminium and magnesium anodes 3.5 External hull protection 3.6 Corrosion protection coatings for salt water ballast spaces and double side skin spaces Section 3 : Corrosion Protection 3.1 General 3.2 Surface preparation, prefabrication primers and paints or coatings

Indian Register of Shipping

Part 3 Page 2 of 10 Contents

Chapter 3 : Principles for Scantlings and Structural DetailsSection 1 : General 1.1 Application 1.2 Symbols 1.3 Frame spacing Section 5 : End Attachments Section 2 : Corrosion Additions 2.1 General 5.1 End attachments of stiffeners 5.2 End attachments of girders 4.2 Effective width of attached plating 4.3 Scantlings of stiffeners 4.4 Scantlings of girders

Section 3 : Plating 3.1 General

Section 6 : Buckling 6.1 General 6.2 Ideal elastic buckling stress

Section 4 : Stiffeners and Girders 6.3 Compressive stress, c 4.1 Determination of span

Chapter 4 : Design LoadsSection 1 : General Section 3 : Design Pressures and Forces 1.1 Scope 3.1 General 1.2 Symbols 3.2 External sea pressures Section 2 : Ship Motions and Accelerations 2.1 Roll and pitch angles 2.2 Acceleration components 2.3 Combined accelerations 3.5 Forces due to heavy units of cargo and equipment 3.3 Internal pressures on tank structures 3.4 Pressures due to dry cargoes, stores, equipment and accommodation



Chapter 5 : Longitudinal StrengthSection 1 : General Section 4 : Shear Strength 1.1 Application 4.1 General 1.2 Symbols 1.3 Terms 4.2 Side shell and longitudinal bulkheads thickness requirement

Section 2 : Vertical Bending Moments and Shear Forces 2.1 Still water bending moment and shear force 2.2 Wave bending moment and shear force

Section 5 : Openings Strength Members 5.1 Locations 5.2 Deductions for openings 5.3 Reinforcements

in

Longitudinal

Section 3 : Hull Section Modulus and Moment of Inertia 3.1 Calculation of section properties

5.4 Hatchway corners

Section 6 : Loading Guidance Information 3.2 Extent of high strength steel 6.1 General 3.3 Section modulus requirement 6.2 Conditions of approval of loading manuals 3.4 Moment of inertia requirement 3.5 Bending strength outside amidships 6.3 Conditions instruments of approval of loading

Chapter 6 : Bar Keel, Stem and SternframesSection 1 : General 1.1 Scope 1.2 Material 1.3 Symbols Section 4 : Stern Frames and Rudder Horns 4.1 General 4.2 Sternframes 4.3 Sole piece 4.4 Shaft brackets Section 2 : Bar Keel 4.5 Rudder horns 2.1 Scantlings Section 5 : Propeller Nozzles Section 3 : Stem 5.1 General 3.1 Bar stem 5.2 Nozzle scantlings and construction details 3.2 Plate stem 5.3 Steerable nozzles 3.3 Strengthening against bow impact 5.4 Fixed nozzles 3.4 Bulbous bowIndian Register of Shipping


Chapter 7 : Bottom StructureSection 1 : General 1.1 Scope 1.2 Symbols Section 5 : Single Bottom 5.1 Transverse framing 5.2 Longitudinal framing

Section 2 : Structural Arrangement and Details 2.1 General

Section 6 : Double Bottom 6.1 General 6.2 Transverse framing

2.2 Access ventilation and drainage 6.3 Longitudinal framing Section 3 : Design Loads 3.1 Bottom shell 3.2 Watertight floors and girders 3.3 Inner bottom Section 7 : Additional Strengthening against Slamming 7.1 General 7.2 Spacing of floors and girders 7.3 Plating and stiffeners Section 4 : Bottom and Inner Bottom Plating 4.1 Keel plate 4.2 Bottom, bilge and inner bottom plating Section 8 : Engine Seatings 8.1 General 8.2 Recommended scantlings

Chapter 8 : Side StructureSection 1 : General Section 4 : Side Shell Plating and Stiffeners 1.1 Scope 4.1 Side shell plating 1.2 Symbols 4.2 Side shell longitudinals Section 2 : Structural Arrangement and Details 2.1 General 4.5 Peak frames 2.2 Sheer strake 4.6 Tripping brackets Section 3 : Design Loads Section 5 : Girders 3.1 External sea pressure 5.1 General 3.2 Internal tank pressureIndian Register of Shipping

4.3 Main frames 4.4 Tween deck frames, super structure frames


Chapter 9 : Deck StructureSection 1 : General 1.1 Scope 1.2 Symbols Section 4 : Deck Platings and Stiffeners 4.1 Deck platings 4.2 Deck stiffeners


Section 5 : Deck Girders and Pillars 5.1 Girders 5.2 Cantilevers

Section 3 : Design Loads

5.3 Pillars

3.1 Weather deck 3.2 Tween decks, accommodation decks platform decks and

Section 6 : Decks for Wheel Loading 6.1 General 6.2 Wheel loads

3.3 Decks forming tank boundaries 6.3 Deck plating 6.4 Deck stiffeners 6.5 Deck girders

Chapter 10 : BulkheadsSection 1 : General 1.1 Scope 1.2 Statutory requirements 1.3 Definitions and symbols 2.6 Doors in watertight bulkheads for ships where subdivision / damage stability requirements are applicable 2.7 Cofferdams 2.8 Fore peak spaces

Section 2 : Subdivision and Arrangement 2.1 Number of bulkheads


2.2 Position of collision bulkhead 3.2 Wash bulkheads 2.3 After peak bulkhead and shaft tunnel 3.3 Supporting bulkheads 2.4 Height of bulkheads 2.5 Openings in watertight bulkheads and closing appliances - General Section 4 : Design Loads 4.1 Watertight bulkhead loads 4.2 Tank bulkhead loadsIndian Register of Shipping


4.3 Wash bulkheads loads

5.4 Vertical and transverse stiffeners on ordinary watertight bulkheads Section 6 : Girders 6.1 General 6.2 Complex girder system

Section 5 : Plating and Stiffeners 5.1 Bulkhead plating 5.2 Longitudinals 5.3 Vertical and transverse stiffeners on tank bulkheads, collision bulkheads, dry bulk cargo bulkheads and wash bulkheads

Chapter 11 : Superstructures, Deckhouses and BulwarksSection 1 : General 1.1 Scope 1.2 Definitions 1.3 Symbols Section 5 : Bulwarks and Guard Rails 5.1 General requirements 5.2 Bulwark construction 5.3 Bulwark scantlings 5.4 Freeing arrangements Section 2 : Design Loads 2.1 External pressure 5.5 Freeing ports in way of wells in combination with open superstructures 5.6 Guard rails Section 3 : Scantlings 3.1 End bulkheads of superstructures and deckhouses and exposed sides in deckhouses 3.2 Protected machinery casings Section 4 : Structural Arrangement and Details 4.1 Structural continuity 6.3 Installation 4.2 Navigation bridge visibility 6.4 Inspection and maintenance 5.7 Protection of crew requirements for specific types Section 6 : Means of Embarkation and Disembarkation 6.1 General 6.2 Construction



Chapter 12 : Openings and Closing AppliancesSection 1 : General 1.1 Scope 1.2 Definitions Section 5 : Side Shell Doors and Stern Doors 5.1 General 5.2 Design loads 5.3 Strength criteria Section 2 : Hatch Coamings 5.4 Scantlings 2.1 Coaming heights 2.2 Hatch coaming construction 2.3 Coaming thickness 2.4 Secondary stiffeners on hatch coaming Section 6 : Bow Doors and Inner Doors 2.5 Coaming stays 6.1 General 2.6 Corrosion additions for hatch coaming 6.2 Design loads Section 3 : Hatch Covers 6.3 Strength criteria 3.1 General 6.4 Scantlings of bow doors 3.2 General strength criteria 6.5 Scantlings of inner doors 3.3 Design loads 6.6 Securing and supporting of bow doors 3.4 Local plate thickness of hatchcover 6.7 Securing and locking arrangement 3.5 Net scantlings of secondary stiffeners 6.8 Operating and maintenance manual 3.6 Net scantlings members 3.7 Hatch cover edges 3.8 Wooden hatch covers 3.9 Portable hatch beams 3.10 Direct calculations 7.3 Manholes and flush hatches Section 4 : Arrangement 4.1 General 4.2 Steel hatch covers 7.6 Openings on engine and boiler casing 4.3 Portable steel covers - tarpaulins and battening devices 7.7 Windows and side scuttles Hatch Cover Securing 7.4 Hatchways within enclosed super-structure and tween decks 7.5 Companionways, doors and accesses on weather decks 7.1 Small openings superstructure decks on freeboard and of primary supporting Section 7 : Miscellaneous Openings 5.5 Securing and supporting of doors 5.6 Securing and locking arrangement 5.7 Operating and maintenance manual

7.2 Additional requirements for small hatches on the exposed fore deck



Chapter 13 : Ventilators, Air Pipes and DischargesSection 1 : General Section 3 : Air and Sounding Pipes 1.1 Scope 3.1 General 1.2 Definitions 3.2 Height of air pipes 1.3 Protection 3.3 Closing appliances 1.4 Strength of attachments of fore deck fittings Section 4 Discharges 4.1 General 4.2 Closing appliances 4.3 Materials for valves, fittings and pipes : Scuppers and Sanitary

Section 2 : Ventilators 2.1 General 2.2 Coamings 2.3 Closing appliances

Chapter 14 : RuddersSection 1 : General 4.2 Double plated rudders 1.1 Scope 4.3 Single plated rudders 1.2 Material Section 5 : Rudder Stock and Pintles 1.3 Testing 5.1 Rudder stock Section 2 : Arrangement and Details 5.2 Pintles and bearings 2.1 General Section 6 : Rudder Couplings Section 3 : Design Loads 6.1 Horizontal bolted couplings 3.1 Rudder force 3.2 Rudder torque 3.3 Bending reactions moments, shear forces and 6.2 Cone couplings without hydraulic arrangement for mounting and dismounting 6.3 Cone couplings with hydraulic arrangement for mounting and dismounting (with oil injection and hydraulic nut) 6.4 Vertical flange couplings 4.1 Construction details

Section 4 : Rudder Blades



Chapter 15 : Anchoring and Mooring EquipmentSection 1 : General Section 5 : Anchor Chain Cables 1.1 Introduction 5.1 General 1.2 Design of the anchoring equipment 5.2 Manufacture and testing 1.3 Documentation 1.4 Symbols Section 6 : Towlines, Mooring Lines and associated Shipboard Fittings 6.1 General 6.2 Manufacture and testing 2.1 General 6.3 Towing and mooring arrangements Section 3 : Equipment Specification 3.1 Equipment number 3.2 Equipment 6.4 Design loads 6.5 Shipboard fittings 6.6 Emergency towing procedure

Section 2 : Structural Arrangement for Anchoring Equipment

Section 4 : Anchors 4.1 General 4.2 High Holding Power (HHP) anchors 4.3 Super High Holding Power (SHHP) anchors

Section 7 : Windlass and Chain Stoppers 7.1 General 7.2 Strength of windlass securing arrangements to resist the green sea loads 7.3 Testing

4.4 Manufacture and testing

Chapter 16 : Masts and RiggingSection 1 : General 1.1 Application 1.2 Documentation Section 3 : Rigging 1.3 Materials 3.1 General Section 2 : Masts 3.2 Stay construction 2.1 Scantlings 2.2 Construction details



Chapter 17 : WeldingSection 1 : General 1.1 Scope 1.2 Documentation Section 3 : Welded Connections Section 2 : Welding 2.1 Welders and supervision 2.2 Welding electrodes 2.3 Preparation for welding 2.4 Welding procedure 3.1 Butt welds 3.2 'T' connections 3.3 Lap connections 3.4 Slot weld 3.5 End connection 2.5 Approval of procedures 2.6 Inspection of welds

Chapter 18 : Hull Inspection, Workmanship and TestingSection 1 : Hull Inspection 1.1 Approval of works 1.2 Inspection facilities Section 3 : Testing 3.1 Definitions 3.2 Application 3.3 Structural testing Section 2 : Workmanship 3.4 Leak testing 2.1 General 3.5 Hose testing 2.2 Plate edges and cut-outs 3.6 Hydropneumatic testing 2.3 Cold forming 3.7 Other testing methods 2.4 Hammering, bending and straightening 3.8 General testing requirements 3.9 Additional requirements for special type vessels/tanks

End of Chapter



Chapter 1 General, Definitions, DocumentationContents Section 1 2 3 General Definitions Documentation

Section 1 General1.1 Scope 1.1.1 The Rules in this part apply to all-welded, single hull sea going steel ships of normal form, proportions and speed. 1.1.2 For additional class notations relating to various ship types, requirements as per Pt.5 are to be complied with. 1.1.3 Ships of unconventional forms and proportions or intended for carriage of cargoes not covered by the Rules or to be engaged in special service will receive individual consideration based on the general principles of the Rules. In these cases, however, additional calculations and/or model testing may be required to be carried out and submitted for approval. 1.1.4 Proposals for use of alternative materials e.g. aluminium, wood, etc. for some parts of the ship shall receive special consideration. 1.2 Equivalence 1.2.1 Alternative arrangements, scantlings and equipment may be accepted provided they can be shown to be equivalent to the overall safety and strength standard of the Rules. Direct calculations for the derivation of the scantlings as an alternative to those derived by the Rule formulae, may be accepted on special consideration. The calculation procedure and the assumptions made are to be submitted for approval. 1.3 National and international regulations 1.3.1 While the Rules cover requirements for the classification of ships, the attention of all concerned is drawn to requirements of various local, national or international Regulations, Codes and Recommendations which the vessel may also have to comply with. 1.4 Stability 1.4.1 All ships with a length of 24 [m] and above will be assigned class only after it has been demonstrated that their intact stability and damage stability (where applicable) are in compliance with the standards laid down by the National statutory authority. The level of intact stability and damage stability in any case should not be less than that required by IMO instruments given in 1.4.2 and 1.4.3 respectively as appropriate. 1.4.2 Intact stability is to be as per the requirements of Chapters 1, 2 and 3 of Part A of the International Code on Intact Stability, 2008 (Resolution MSC 267(85)). For the following types of ships, in case the Administration concerned has not laid down criteria for intact stability, it is recommended that the criteria indicated below or their equivalents are satisfied: For pontoons of all sizes : Ch.2, Sec 2.2 of Part B of the International Code on Intact Stability, 2008 (Resolution MSC 267(85)).


Chapter 1 Page 2 of 7

Part 3 General, Definitions, Documentation

1.4.3 All ships are required to comply with the applicable damage stability requirements in accordance with the following: a) Part B and Part B-1 through B-4 of Chapter II-1 of SOLAS 1974 as adopted by IMO Resolution MSC 216(82) for passenger ships regardless of length and cargo ships having load line length LL of 80 [m] and above. Cargo ships which are shown to comply with any other damage stability regulations indicated in the following (1.4.3 b) to g)) are excluded from the applicability of the above. b) Regulation 27 of ILLC 1966 as applied to tankers and dry cargo vessels in compliance with Resolutions A.320(IX) and A.514(13) provided that in the case of ships to which regulation 27(9) applies, main transverse watertight bulkheads, to be considered effective, are spaced according to paragraph 12(f) of resolution A.320(IX). Compliance with Reg.27 of ILLC Protocol 1988 is accepted as equivalent to the above. In case ships for which Reg.27 of ILLC applies are intended to carry deck cargo also, then a limiting GM or KG curve is to be provided to the master in the stability manual based on compliance with the probabilistic damage stability analysis of SOLAS Chapter II-1 Part B-1. In such cases the KG used for demonstrating compliance with the deterministic damage stability requirements of ILLC Reg.27 should be same as that used for the probabilistic damage stability calculations required by SOLAS Ch.II-1 Part B-1 at the deepest subdivision loadline. c) Annex I (Regulation 28) of MARPOL 1973/78, for Oil Tankers except that combination carriers with Type B freeboard are not excluded. d) IBC Code, as amended for Chemical Tankers in general. e) IGC Code, as amended for Liquefied Gas Carriers. f) Resolution MSC Supply Vessels. 235(82) for Offshore

1.4.4 An approved stability information manual is to be available on board for guidance to the master as to the stability of the ship under varying conditions of service. This is to be prepared on the basis of MSC Circular 920 Model Loading and Stability Manual. Additionally, full details of the stability criteria appropriate to the ship under all anticipated conditions of service are to be clearly stated in text supplemented by diagrams using the nomenclature adopted in the manual. Full details of any requirements for wind and/or wave forces and ice accretion specified by the Administration are also to be provided. 1.5 Damage control plan and booklet for dry cargo and passenger ships 1.5.1 Plan : The damage control plan is to include inboard profile, plan views of each deck and transverse sections to the extent necessary to show the following: the watertight boundaries of the ship; the locations and arrangements of crossflooding systems and any other system for correction of list; the locations of all internal watertight closing appliances including on ro-ro ships, internal ramps or doors and their controls, position indicators, alarms and special precautions required, if any, for the closing appliances during voyage; the locations of all doors in the shell of the ship, position indicators, leakage detection and surveillance devices; the locations of all weathertight closing appliances in local subdivision boundaries above the bulkhead deck and on the lowest exposed weather decks, together with locations of controls and position indicators, if applicable; the locations, arrangement and control positions of the entire bilge and ballast system.

-

-

-

-

1.5.2 Booklet : The damage control booklet is to contain aforementioned information as in the plan and in addition general instructions for controlling the consequential effects of damage as follows: shutting off the closing appliances;

g) Resolution MSC Purpose Ships.

266(84)

for

Special


Rules and Regulations for the Construction and Classification of Steel Ships - 2011 Page 3 of 7 ___________________________________________________________________________________ ensuring the safety of personnel onboard; ascertaining extent of damage and rates of flooding by sounding; cautionary advise regarding causes of any list; required liquid transfer operations to lessen list or trim and the resulting effects of additional free surfaces; initiating pumping operations to control the ingress of water; 1.5.4 For cargo ships the plan is to be permanently exhibited or readily available on the navigating bridge and in the cargo control room, where applicable. 1.6 Protective location of fuel oil tanks 1.6.1 All ships with an aggregate oil fuel capacity of 600 [m3] and above are to satisfy the requirements for oil fuel tank protection as given in MARPOL Reg.I/12A. For this purpose, the distances of the oil fuel tanks above the bottom shell and inboard of the side shell are to be not less than the values specified in the above MARPOL Regulation. Alternatively, such ships may comply with the accidental oil outflow performance standard specified in paragraph 11 of MARPOL Reg. I/12A. 1.6.2 Small oil fuel tanks of capacity not greater than 30 [m3] are exempted from the requirements for protective location of the above MARPOL Regulation provided the aggregate capacity of such exempted tanks is not greater than 600 [m3]. 1.7 Assumptions 1.7.1 It is assumed that significant dynamic excitation of major orders from propellers and machinery do not fall close to any natural frequency of the hull. 1.7.2 It is assumed that the ships will be competently handled and loaded as per the approved loading manuals.

-

-

The booklet should provide: details of sounding devices, tank vents and overflows; pump capacities and piping diagrams; operating system; procedure of cross-flooding

-

-

locations of non-watertight openings with non-automatic closing devices through which progressive flooding can occur; details of access and means of escape for personnel to and from compartments; procedure for alerting ship management and other organisations for obtaining and coordinating assistance;

-

-

1.5.3 For passenger ships, the plan is to be permanently exhibited on the navigating bridge, as well as in the ship's control station, or equivalent.

Section 2 Definitions2.1 Principal particulars 2.1.1 The forward perpendicular, F.P., is the perpendicular drawn at the intersection of the summer load water line with the fore side of the stem. In ships with unusual bow arrangement the position of the F.P. will be specially considered. 2.1.2 The after perpendicular, A.P., is the perpendicular drawn at the intersection of the summer load waterline with the after side of the rudder post or the centreline of the rudder stock if there is no rudder post. In ships with unusual stern arrangement the position of the A.P. will be specially considered. 2.1.3 Rule length, L, is the distance, [m], between the forward and after perpendiculars. However L is to be not less than 96 per cent, and need not be greater than 97 per cent of the extreme length on the summer load waterline.




In ships with unusual bow and/or stern arrangement the Rule length, L, will be specially considered. 2.1.4 "Amidship" is at 0.5L aft of the F.P. 2.1.5 Breadth, B, is the greatest moulded breadth [m]. 2.1.6 Depth, D, is the moulded depth [m], measured amidships from top of the keel to the moulded deck line of the uppermost continuous deck at side. When a rounded gunwale is arranged the depth is to be measured to the continuation of the moulded deck line. 2.1.7 Draught, T, is the moulded draught amidships corresponding to the summer load waterline, [m]. 2.1.8 The block co-efficient, Cb, is the moulded block co-efficient calculated as follows :-

openings on the sides of the ship are fitted with means for watertight closing. Superstructure : A decked structure on freeboard deck extending from side to side of the ship or with the side plating not inboard of shell plating by more than 4 per cent of the breadth B. Deckhouse : A decked structure above the freeboard deck with the side plating being inboard of the shell plating by more than 4 per cent of the breadth B. Bottom Structure : Shell plating with stiffeners and girders below the upper turn of bilge and all other elements below and including the inner bottom plating in case of the double bottom. Sloping hopper tank top is to be regarded as a bulkhead. Side Structure : Shell plating with stiffeners and girders between the upper turn of bilge and the uppermost continuous deck at side. A rounded gunwale is included in the side structure. Deck Structure : Deck plating with stiffeners, girders, and supporting pillars. Girder : A collective term for the primary supporting members, other terms include : Transverses - transverse girders under the deck. Web frames - side vertical girders. Hatch end beams - transverse deck girders at the ends of the hatch. Stringers - horizontal girders. Cross-ties - girders connecting two vertical girders in a deep tank. Floor - bottom transverse girders.

-

-

Cb =

moulded displacement [m 3 ] at draught T LBT-

2.1.9 Load line length, LL , is to be taken as 96 per cent of the total length [m], on a waterline at 85 per cent of the least moulded depth measured from the top of the keel, or as the length from the fore side of the stem to the axis of the rudder stock on that waterline, if that is greater. In ships designed with a rake of keel, the waterline on which this length is measured is to be parallel to the designed waterline. 2.1.10 Speed, V, is the maximum service speed in knots on draught T. 2.2 Structural terms 2.2.1 The general terms used in the Rules for various structural parts of the ships are defined as under: Strength Deck : In general the uppermost continuous deck. Where a superstructure deck has within 0.4L amidships, a continuous length equal to or greater than (1.5B + 3H), it is to be regarded as the strength deck instead of the covered part of the uppermost continuous deck. (H is the height of the superstructure, [m]). Freeboard Deck : The freeboard deck is normally the uppermost complete deck exposed to weather and sea, which has permanent means of closing all openings in the weather part and below which all

-

-

-

-

Stiffener : A collective term for secondary supporting members; other terms being : Frames. Bottom, inner bottom, side or deck longitudinals. Reverse frame - transverse stiffener on the inner bottom.

-

-


Rules and Regulations for the Construction and Classification of Steel Ships - 2011 Page 5 of 7 ___________________________________________________________________________________ Horizontal stiffeners. or vertical bulkhead 2.3 Material factor 2.3.1 Material factor, k, a factor depending on material strength is defined in Ch.2.

-

Other terms are defined in the appropriate Chapters.

Section 3 Documentation3.1 General 3.1.1 Documentation is to be submitted as per the following paragraphs. In case of certain ship types additional documentation may be required as per Pt.5. 3.1.2 he documents should be submitted in triplicate, one copy of which shall be returned. 3.2 Plans for information 3.2.1 The following supporting plans and calculations are to be submitted for information : General arrangement. Tank plan. Capacity plan. Lines plan and Hydrostatic curves or tables. Docking plan. 3.4.1 Plans as relevant are to be submitted for approval as indicated in Table 3.4.1. These should as far as practicable be complete in all necessary details. 3.5 Plans to be kept on board 3.5.1 A set of as built construction drawings and other plans showing any subsequent structural alterations are to be kept on board. The set of plans are to include the following: a) Main plans i) ii) iii) iv) General arrangement Capacity plan Hydrostatic curves Loading manual, where required

b) Structural plans i) ii) iii) iv) v) vi) vii) Midship section Scantling profile Decks Shell expansion Transverse bulkheads Rudder and rudder stock Cargo hatch covers, when applicable

3.3 Additional information 3.3.1 The following additional information is to be submitted as necessary for strength calculations: Maximum values of still water bending moments and shear forces. Lightship weight distribution. Bonjeans data. Stowage factor and angle of repose of bulk cargoes to be carried. Masses and unbalanced moments of heavy machinery components e.g. engines, cranes, winches etc. and its longitudinal

c) Bilge ballast and cargo piping diagrams. An additional set of such drawings are to be kept ashore by the company responsible for the operation of the ship. 3.5.2 To facilitate the ordering of materials for repairs, the above plans are to show the disposition and extent of high strength steel and steel of grades other than Grade A, along with the information relating to their physical and mechanical properties, recommended working, treatment and welding procedures etc.

-

-

-

3.4 Plans for approval




3.5.3 A ship construction file is required to be maintained on board the ship to facilitate inspection (survey) and repair and maintenance in future. The ship construction file to contain : a) Plans as mentioned at 3.5.1; b) Essential certificates and records;

e) Tank testing plan including details of the test requirements; f) Corrosion protection specifications;

g) Details for the in-water survey, if applicable, information for divers, clearances measurements instructions etc. tank and compartment boundaries; h) Docking plan and details of all penetrations normally examined at drydocking; i) Coating technical file, for ships subject to compliance with the IMO Coating Performance Standard (PSPC). (See Part 3, Chapter 2, Section 3.6).

c) Manuals required for classification and statutory requirements; d) Details of equipment forming part of the watertight and weathertight integrity of the ship;



Table 3.4.1 : Plans for approval Plan Loading manual 1) Including Information On details of loading in all contemplated loading conditions and resulting SWBM, SF and Torsional Moments (TM) design values of SWBM, SF & TM main particulars (L, B, D, T, Cb, V) equipment specification complete class notation applied for spacing of stiffeners deck loads, if other than those specified in the Rules openings on the deck minimum ballast draught(s) extent of flat part of bottom forward openings on the shell material grades indication of access height and location of overflows loading on inner bottom openings and their closing appliances propeller outline propeller thrust structural details in way of rudder and propeller bearings height and location of overflow type, power and r.p.m. of propulsion machinery weight of machinery, boilers, etc. openings on non-watertight bulkheads and diaphragm plates height and location of overflows intended tank contents & their densities height and location of overflow/air pipes tanks intended to be partially filled corrosion protection; if any height of sills from deck and closing appliances for companionways position and type loads if different from those specified in the rules sealing and securing arrangement, spacing of bolts or wedges speed of the ship (head & astern) material of bearings, coupling bolts, stock and the locking device rudder carrier derrick length and loading dimensions and positions of stays and shrouds quality of material material grade

Midship section Other transverse sections Longitudinal sections & decks Shell expansion & framing plan

Double bottom

Watertight subdivision bulkheads & watertight tunnels Aft-end structure Stern frame or sternpost Propeller shaft brackets Aft peak tank Engine room structure Engine and thrust block seatings Fore-end construction Fore peak tank Oil tight/water tight and partition bulkheads in cargo tanks, ballast tanks and deep tanks Superstructures, deckhouses and machinery castings Hatchways Hatch covers Bow & stern doors Side ports Rudder, stock and tiller Steering gear arrangement

Masts & derrick posts Support structure for masts, derrick posts & cranes Bilge keel Testing plan of tanks & bulkheads Welding details Note:

1) See Chapter 5, Section 6. 2) One drawing may contain more than one of the items from each group.

End of ChapterIndian Register of Shipping


Chapter 2 Materials of ConstructionContents Section 1 2 3 4 General Use of Steel Grades Corrosion Protection Deck Covering

Section 1 General1.1 Scope 1.1.1 The Rules relate, in general, to the construction of steel ships. Consideration will however be given to the use of other materials also. 1.1.2 The materials used in the construction of the ship are to be manufactured and tested in accordance with the requirements of Pt.2. Materials for which provision is not made in Pt.2 may be accepted, provided that they comply with an approved specification and such tests as may be considered necessary. 1.2 Steel 1.2.1 Ordinary hull structural steel is a hull structural steel with a minimum yield stress of 235 [N/mm2] and a tensile strength generally in the range of 400-490 [N/mm2]. For ordinary hull structural steel, the material factor `k' is to be taken as 1.0. 1.2.2 Steels having a yield stress of 265 [N/mm2] and higher, are regarded as higher tensile steels. Where higher tensile steel is used, the hull girder section modulus and the local scantlings may be reduced in accordance with the relevant requirement of the Rules. For this purpose, a material factor 'k', is to be taken as follows: k = 0.78 for steel with a minimum yield stress of 315 [N/mm2] k = 0.72 for steel with minimum yield stress of 355 [N/mm2] k = 0.68 for steel with minimum yield stress of 390 [N/mm2]. 1.2.3 Where steel castings or forgings are used for sternframes, rudderframes, rudder stocks, propeller shaft brackets and other major structural items, they are to comply with Pt.2 as appropriate. 1.3 Aluminium 1.3.1 Where seawater resisting aluminium alloys manufactured and tested in accordance with the requirements of Pt.2 are used for superstructures, deckhouses, hatch covers, helicopter decks or other structural components, scantlings equivalent to steel are to be derived as follows: plating thickness, ta = ts

ka

section modulus of stiffeners, Za = Zs.ka where, ta, ts = plating thickness of aluminium and mild steel respectively. Za, Zs = section modulus of aluminium and mild steel stiffeners respectively.



Part 3 Materials of Construction

235 k = a aa = 0.2% proof stress of the aluminium alloy in the welded condition or 70% of the ultimate strength in the welded condition, whichever is lesser [N/mm2].

1.3.2 The smaller modulus of elasticity of aluminium is to be taken into account, when determining the buckling strength of structural elements subjected to compression and the deflections, where relevant.

Section 2 Use of Steel Grades2.1 Grades of steel 2.1.1 The resistance to fracture is controlled, in part, by the notch toughness of the steel used in the structure. Steels with different levels of notch toughness are specified in Pt.2. The grade of steel to be used is, in general, related to the air temperature in the area of operation, thickness of the material and the stress pattern associated with its location. 2.1.2 The grades of steel to be used for structures of ships in normal world wide service and those exposed to low air temperatures ( 20C ), are given in Sec 2.2 and 2.3 respectively. The grades of steel to be used for certain hull members in refrigerated spaces are given in Sec 2.4. 2.1.3 Where tee or cruciform connections employ full penetration welds, and the plate material is subject to significant strains in a direction perpendicular to the rolled surfaces, it is recommended that consideration be given to the use of special plate material with specified through thickness properties, as detailed in Pt.2. 2.2 Ships in normal world wide service 2.2.1 Materials in the various strength members are not to be of lower grade than those corresponding to material classes and grades specified in Tables 2.2.1a) to 2.2.1e). General requirements are given in Table 2.2.1a), while additional minimum requirements for specific cases are given in Tables 2.2.1b) to 2.2.1e). 2.2.2 The material grade requirements for hull members of each class depending on thickness are defined in Table 2.2.2.



Table 2.2.1a) : Material classes and grades for ships in general Structural member category SECONDARY: Longitudinal bulkhead strakes, other than that belonging to the primary category Deck plating exposed to weather, other than that belonging to the primary or special category Side plating PRIMARY: Bottom plating, including keel plate Strength deck plating, excluding that belong to the special category Continuous longitudinal members above strength deck, excluding hatch coamings Uppermost strake in longitudinal bulkhead Vertical strake (hatch side girder) and uppermost sloped strake in top wing tank SPECIAL: Sheer strake at strength deck (1) Stringer plate in strength deck (1) Deck strake at longitudinal bulkhead, excluding deck plating in way of inner skin bulkhead of double hull ships (1) Strength deck plating at outboard corners of cargo hatch openings in container carriers and other ships with similar hatch opening configurations Class III within 0.4L amidships Class II outside 0.4L amidships Class I outside 0.6L amidships Class II within 0.4L amidships Grade A/AH outside 0.4L amidships Class I within 0.4L amidships Grade A/AH outside 0.4L amidships Material class/grade

-

Class III within 0.4L amidships Class II outside 0.4L amidships Class I outside 0.6L amidships Min. class III within cargo region Class III within 0.6L amidships Class II within rest of cargo region Class II within 0.6L amidships Class I outside 0.6L amidships Class III within 0.4L amidships Class II outside 0.4L amidships Class I outside 0.6L amidships Class III within 0.4L amidships Class II outside 0.4L amidships Class I outside 0.6L amidships Not to be less than Grade D/DH

Strength deck plating at corners of cargo hatch openings in bulk carriers, ore carriers combination carriers and other ships with similar hatch opening configurations Bilge strake in ships with double bottom over the full breadth and length less than 150 m (1) Bilge strake in other ships (1)

Longitudinal hatch coamings of length greater than 0.15L End brackets and deck house transition of longitudinal cargo hatch coamings

-

(1) Single strakes required to be of Class III within 0.4L amidships are to have breadths not less than 800+5L [mm], need not be greater than 1800 [mm], unless limited by the geometry of the ships design.




Table 2.2.1b) : Minimum material grades for ships with length exceeding 150 m and single strength deck Structural member category Longitudinal strength members of strength deck plating Continuous longitudinal strength members above strength deck Single side strakes for ships without inner continuous longitudinal bulkhead(s) between bottom and the strength deck Material grade Grade B/AH within 0.4L amidships Grade B/AH within 0.4L amidships Grade B/AH within cargo region

Table 2.2.1c) : Minimum material grades for ships with length exceeding 250 m Structural member category Sheer strake at strength deck (1) Stringer plate at strength deck (1) Bilge strake (1) Material grade Grade E/EH within 0.4L amidships Grade E/EH within 0.4L amidships Grade D/DH within cargo region

(1) Single strakes required to be of Grade E/EH and within 0.4L amidships are to have breadths not less than 800+5L [mm], need not be greater than 1800 [mm], unless limited by the geometry of the ships design.

Table 2.2.1d) : Minimum material grades for single-side skin bulk carriers subjected to SOLAS Regulation XII/6.5.3 (3) Structural member category Lower bracket of ordinary side frame (1), (2) Side shell strakes included totally or partially between the two points located to 0.125l above and below the intersection of side shell and bilge hopper sloping plate or inner bottom plate (3) Material grade Grade D/DH Grade D/DH

(1) The term lower bracket means webs of lower brackets and webs of the lower part of side frames upto the point of 0.125l above the intersection of side shell and bilge hopper sloping plate or inner bottom plate. (2) The span of the side frame, l, is defined as the distance between the supporting structures. (3) SOLAS Regulation XII/6.5.3 applies to bulk carriers of LL 150 m, carrying solid bulk cargoes having a density of 1000 [kg/m3] and above constructed on or after 1 July 2006.

Table 2.2.1e) : Minimum material grades for ships with ice strengthening Structural member category Shell strakes in way of ice strengthening area for plates (See Part 5, Chapter 21) Grade B/AH Material grade



Table 2.2.2 : Material grade requirements for classes, I, II and III Class I II III Thickness MS HT MS HT MS HT [mm] A AH A AH A AH t 15 A AH A AH B AH 15 < t 20 A AH B AH D DH 20 < t 25 A AH D DH D DH 25 < t 30 B AH D DH E EH 30 < t 35 B AH D DH E EH 35 < t 40 D DH E EH E EH 40 < t 50 Notes: 1. For strength members not mentioned in Table 2.2.1a) to Table 2.2.1e), grade A/AH may generally be used. 2. The steel grade is to correspond to the as-built plate thickness when this is greater than the rule requirement. 3. Plating materials for sternframes, rudders, rudder horns and shaft brackets are in general not to be of lower grades than corresponding to class II. For rudder and rudder body plates subjected to stress concentrations (e.g. in way of lower support of semi-spade rudders or at upper part of spade rudders) class III is to be applied.

2.3 Structures exposed to low air temperatures 2.3.1 For ships intended to operate in areas with low air temperatures (below and including 20C), e.g. regular service during winter seasons to Arctic or Antarctic waters, the materials in exposed structures are to be selected based on the design temperature tD as defined in 2.3.2. 2.3.2 The design temperature tD is to be taken as the lowest mean daily average air temperature in the area of operation as illustrated in Fig.2.3.2. Mean : Statistical mean over observation period (at least 20 years). Average : Average during one day and night. Lowest : Lowest during year.

MDAT = Mean Daily Average Temperature MDLT = Mean Daily Temperature. Low (or minimum)

For seasonally restricted service the lowest value within the period of operation would be applicable. 2.3.3 Materials in the various strength members above the lowest ballast water line (BWL) exposed to air are not to be of lower grades than those corresponding to classes I, II and III as given in Table 2.3.3, depending on the categories of structural members (SECONDARY, PRIMARY and SPECIAL). For non-exposed structures and structures below the lowest ballast water line, See 2.2. 2.3.4 The material grade requirements for hull members of each class depending on thickness and design temperature are defined in Table 2.3.5. For design temperatures tD < -55C, materials will be specially considered.

MDHT = Mean Daily High (or maximum) Temperature




Table 2.3.3 : Application of material classes and grades Structures exposed to low temperatures Material class/grade Within 0.4L amidships Outside 0.4L amidships

Structural member category SECONDARY: Deck plating exposed to weather, in general Side plating above BWL Transverse bulkheads above BWL PRIMARY: Strength deck plating (see Note 1) Continuous longitudinal members above strength deck, excluding longitudinal hatch coamings Longitudinal bulkhead above BWL Top wing tank bulkhead above NWL SPECIAL: Sheer strake at strength deck (see Note 2) Stringer plate in strength deck (see Note 2) Deck strake at longitudinal bulkhead (see Note 3) Continuous longitudinal hatch coamings (see Note 4)

I

I

II

I

III

II


Rules and Regulations for the Construction and Classification of Steel Ships - 2011 Page 7 of 12 ___________________________________________________________________________________ Table 2.3.3. (Contd.) Notes: 1. Plating at corners of large hatch openings to be specially considered. Class III or grade E/EH to be applied in positions where high local stresses may occur. 2. Not to be less than grade E/EH within 0.4L amidships in ships with length exceeding 250 [m]. 3. In ships with breadth exceeding 70 [m] at least three deck strakes to be class III. 4. Not to be less than grade D/DH.

Table 2.3.4 : Material grade requirements for classes I, II and III at low temperatures Class I Plate thickness [mm] t 10 10 < t 15 15 < t 20 20 < t 25 25 < t 30 30 < t 35 35 < t 45 45 < t 50 Plate thickness [mm] t 10 10 < t 20 20 < t 30 30 < t 40 40 < t 45 45 < t 50 Plate thickness [mm] t 10 10 < t 20 20 < t 25 25 < t 30 30 < t 35 35 < t 40 40 < t 50 -20/-25C MS A B B D D D D E HT AH AH AH DH DH DH DH EH -26/-35C MS B D D D D D E E HT AH DH DH DH DH DH EH EH Class II -36/-45C MS D D D D E E E X HT DH DH DH DH EH EH EH EH -46/-55C MS D D E E E E X X HT DH DH EH EH EH EH FH FH

-20/-25C MS B D D E E E HT AH DH DH EH EH EH

-26/-35C MS D D E E X X HT DH DH EH EH FH FH Class III

-36/-45C MS D E E X X X HT DH EH EH FH FH FH

-46/-55C MS E E X X X X HT EH EH FH FH X X

-20/-25C MS D D E E E E X HT DH DH EH EH EH EH FH

-26/-35C MS D E E E X X X HT DH EH EH EH FH FH FH

-36/-45C MS E E X X X X X HT EH EH FH FH FH FH X

-46/-55C MS E X X X X X X HT EH FH FH FH X X X


Chapter 2 Page 8 of 12 Table 2.3.4 (Contd.) Notes:


1. X = Not applicable. 2. Single strakes required to be of class III or of grade E/EH of FH are to have breadths not less than 800 + 5.L [mm] maximum 1800 [mm]. 3. Plating materials for sternframes rudder horns, rudders and shaft brackets are not to be of lower grades than those corresponding to the material classes given in Sec.2.2.

2.4 Refrigerated spaces 2.4.1 Where the minimum design temperature of the steel falls below 0C in refrigerated spaces, in addition to the requirements of 2.2.1, the grade of steel for the following items is to comply, in general, with the requirements of Table 2.4.1: Deck plating. Webs of deck girders.

-

Longitudinal bulkhead strakes attached to deck. Shelf plates and their face bars supporting hatch covers.

2.4.2 Unless a temperature gradient calculation is carried out to assess the design temperature in the items defined in 2.4.1, the temperature to which the steel deck may be subjected is to be assessed as shown in Table 2.4.2.

Table 2.4.1 : Grades of steel for minimum design temperatures below 0C Min. design temp. in C Thickness, in mm t 12.5 12.5 t 25.5 t > 25.5 t 12.5 t > 12.5 t 12.5 t > 12.5 Grades of steel B/AH D/DH E/EH D/DH E/EH E/EH C-Mn LT 60 or 1/2 Ni steels

0 to -10 -10 to -25 -25 to -40

Table 2.4.2 : Assessment of deck temperature Arrangement 1) 2) Deck not covered with insulation in the refrigerated space Deck covered with insulation in the refrigerated space and not insulated on the other side Deck covered with insulation on both sides a) Temperature difference less than or equal to 11C b) Temperature difference greater than 11C but not greater than 33C c) Temperature difference greater than 33C Note: Where one of the internal spaces concerned is not refrigerated, the temperature of the space is to be taken as 5C. Deck temperature Temperature of the refrigerated space Temperature of the space on the un-insulated side

3)

Mean of the temperatures of the spaces above and below the deck Mean of the temperatures of the spaces above and below the deck less 3C Deck temperature will be specially assessed



Section 3 Corrosion Protection3.1 General 3.1.1 All steelwork, except inside tanks intended for the carriage of oil or bitumen, is to be protected against corrosion by application of suitable coating. For protection required in salt water ballast spaces, See 3.6. For protection required in holds of dry bulk cargo carriers, see Pt.5, Ch.1, Sec. 2.11. For the protection required in tanks carrying chemicals or other special cargoes, See Pt. 5, Ch.3. 3.1.2 Where bimetallic connections are made, measures are to be incorporated to preclude galvanic corrosion. 3.2 Surface preparation, prefabrication primers and paints or coatings 3.2.1 Steelwork is to be cleared of millscale and suitably cleaned before the application of surface paints and coatings. It is recommended that blast cleaning or other equally effective means be employed for this purpose. 3.2.2 Where a primer is used to coat steel after surface preparation and prior to fabrication, the composition of the coating is to be such that it will have no significant deleterious effect on subsequent welding work and that it is compatible with the paints or other coatings subsequently applied. 3.2.3 To determine the influence of the primer coating on the characteristics of welds, tests are to be made as detailed in 3.2.4 to 3.2.6. 3.2.4 Three butt weld assemblies are to be tested using plate material 20 to 25 [mm] thick. A 'V' preparation is to be used and, prior to welding, the surfaces and edges are to be treated as follows:a) Assembly 1 - Coated in accordance with the manufacturer's instructions. b) Assembly 2 - Coated to a thickness approximately twice the manufacturer's instructions. c) Assembly 3 - Uncoated.Indian Register of Shipping

3.2.5 Tests as follows are to be taken from each test assembly:a) Radiographs - These are to have a sensitivity of better than 2 per cent of the plate thickness under examination, as shown by an image quality indicator. b) Photo-macrographs - These may be of actual size and are to be taken from near each end and from the centre of the weld. c) Face and reverse bend test - The test specimens are to be bent by pressure or hammer blows round a former of diameter equal to 3 times the plate thickness. d) Impact tests - These are to be carried out at ambient temperature, on three Charpy Vnotch test specimens prepared in accordance with Pt.2. The specimens are to be notched at the centreline of the weld, perpendicular to the plate surface. 3.2.6 The tests are to be carried out in the presence of a Surveyor of IRS or by an independent laboratory specializing in such work. A copy of the test report is to be submitted, together with radiographs and macrographs. 3.2.7 Paints or other coatings are to be suitable for the intended purpose in the locations where they are to be used. Unless previously agreed, at least two coats are to be applied. 3.2.8 The paint or coating is to be compatible with any previously applied primer, See 3.2.2. 3.2.9 Paints, varnishes and similar preparations having a nitrocellulose or other highly flammable base, are not to be used in accommodation or machinery spaces. 3.2.10 In ships intended for the carriage of oil cargoes having a flash point below 60C (closed cup test), paint containing aluminium should not in general be used in cargo tanks, adjacent ballast tanks, cofferdams, pump rooms as well as on deck above the mentioned spaces, nor in any other areas where cargo vapours may accumulate, unless it has been shown by appropriate tests that the paint to be used does not increase the incentive sparking hazard.



3.3 Internal cathodic protection 3.4 Aluminium and magnesium anodes 3.3.1 Impressed current cathodic protection systems are not permitted in any tank. When a cathodic protection system is to be fitted in tanks for the carriage of liquid cargo with flash point not exceeding 60C, a plan showing details of the locations and attachment of anodes is to be submitted. The arrangements will be considered for safety against fire and explosion aspects only. 3.3.2 Particular attention is to be given to the locations of anodes in relation to the structural arrangements and openings of the tank. 3.3.3 Anodes are to be of approved design and sufficiently rigid to avoid resonance in the anode support. Weldable steel cores are to be fitted, and these are to be so designed as to retain the anode even when the anode is wasted. 3.3.4 Anodes are to be attached to the structure in such a way that they remain secure both initially and during service. The following methods of attachment would be acceptable : a) Steel core connected to the structure by continuous welding of adequate section. b) Steel core bolted to separate supports, provided that a minimum of two bolts with lock nuts are used at each support. The separate supports are to be connected to the structure by continuous welding of adequate section. c) Approved means of mechanical clamping. 3.3.5 Anodes are to be attached to stiffeners, or may be aligned in way of stiffeners on plane bulkhead plating, but they are not to be attached to the shell. The two ends are not to be attached to separate members which are capable of relative movement. 3.3.6 Where cores or supports are welded to the main structure, they are to be kept clear of the toes of brackets and similar stress raisers. Where they are welded to asymmetrical stiffeners, they are to be connected to the web with the welding kept at least 25 [mm] away from the edge of the web. In the case of stiffeners or girders with symmetrical face plates, the connection may be made to the web or to the centreline of the face plate but well clear of the free edges. However, it is recommended that anodes are not fitted to face plates of high strength steel longitudinals. 3.4.1 Aluminium and aluminium alloy anodes are permitted in oil cargo tanks and also in tanks adjacent to oil cargo tanks only at locations where the potential energy does not exceed 275 [J] (i.e. 28 [kgf m]). The weight of the anode is to be taken as the weight at the time of fitting, including any inserts and fitting devices. 3.4.2 The height of the anode is, in general, to be measured from the bottom of the tank to the centre of the anode. Where the anode is located on or closely above a horizontal surface (such as a bulkhead girder) not less than 1 [m] wide, provided with an upstanding flange or face plate projecting not less than 75 [mm] above the horizontal surface, the height of the anode may be measured above that surface. 3.4.3 Aluminium anodes are not to be located under tank hatches or tank cleaning openings unless protected by adjacent structure. 3.4.4 Magnesium or magnesium alloy anodes are not permitted in oil cargo tanks and in tanks adjacent to oil cargo tanks. 3.5 External hull protection 3.5.1 Suitable protection for the underwater portion of the hull is to be provided. 3.5.2 Where an impressed current cathodic protection system is fitted, plans showing the proposed layout of anodes, reference cells, wiring diagram and the means of bonding-in of the rudder and propeller, are to be submitted. 3.5.3 The arrangements for glands, where cables pass through the shell, are to include a small cofferdam. Cables to anodes are not to be led through tanks intended for the carriage of low flash point oils. Where cables are led through cofferdams or clean ballast tanks of tankers, they are to be enclosed in a substantial steel tube of about 10 [mm] thickness. 3.6 Corrosion protection coatings for salt water ballast spaces and double side skin spaces 3.6.1 The following spaces are to be coated during construction in accordance with the Performance Standards for Protective Coatings (PSPC) adopted by the IMO by Resolution MSC.215(82), as per applicability indicated in 3.6.2.


Rules and Regulations for the Construction and Classification of Steel Ships - 2011 Page 11 of 12 ___________________________________________________________________________________ a) Dedicated salt water ballast tanks in all ships of 500 GT and above. b) Double side skin spaces in bulk carriers of LL 150 m. The following tanks are not considered to be dedicated salt water ballast tanks and therefore need not comply with the requirement of IMO PSPC: i) Salt water ballast tanks identified as Spaces included in Net Tonnage in the 1969 International Tonnage Convention Certificate; ii) Salt water ballast tanks in passenger vessels also designated for the carriage of grey water. 3.6.2 The IMO Performance Standards for Protective Coatings (PSPC) are to be applied to ships as follows: i) In case of bulk carriers and tankers that are subject to the IACS common structural rules: which are contracted for construction on or after 8 December, 2006. agreeing to the specifications coatings and their application. for the

b) The scheme for the selection, application and maintenance of the coating system to follow the requirements of IMO Resolution A.798(19) and contain, as a minimum the following documentation: Owners, coating manufacturers and shipyards explicit agreement to the scheme for coating selection, application and maintenance. List of seawater ballast tanks identifying the coating system for each tank, including coating color and whether coating system is a hard coating. Details of anodes, if used. Manufacturers technical product data sheet for each product. Manufacturers evidence of product quality and ability to meet owners requirements. Evidence of shipyards and/or its subcontractors experience in coating application. Surface preparation procedures and standards, including inspection points and methods. Application procedures and standards, including inspection points and methods. Format for inspection reports on surface preparation and coating application. Manufacturers product safety data sheets for each product and owners, coating manufacturers and shipyards explicit agreement to take all precautions to reduce health and other safety risks which are required by the authorities. Maintenance requirements coating system. for the

ii) In case of all ships other than those mentioned in i) above: Which are contracted for construction on or after 1 July 2008, or In the absence of a building contract, the keels of which are laid or which are at a similar stage of construction on or after 1 January 2009, or The delivery of which is on or after 1 July 2012.

-

-

-

3.6.3 For oil tankers and bulk carriers constructed on or after 1 July 1998 and for which 3.6.1 and 3.6.2 are not applicable, the following are to be complied with: a) All salt water ballast spaces are to have an efficient corrosion protection hard coating, epoxy or equivalent, applied in accordance with the manufacturer's requirements. The durability of the coatings could affect the frequency of survey of the spaces and light coloured coatings would assist in improving the effectiveness of subsequent surveys. It is therefore recommended that these aspects be taken into account by those

-

-

-




Section 4 Deck Covering4.1 General 4.1.1 Where plated decks are sheathed with wood or an approved composition, reductions in plate thickness may be allowed. 4.1.2 The steel deck is to be coated with a suitable material in order to prevent corrosive action, and the sheathing or composition is to be effectively secured to the deck. 4.1.3 Deck coverings in the following positions are to be of a type which will not readily ignite where used on decks : a) forming the crown of machinery or cargo spaces within accommodation spaces of cargo ships b) within accommodation spaces, control stations, stairways and corridors of passenger ships.

End of Chapter



Chapter 3 Principles for Scantlings and Structural DetailsContents Section 1 2 3 4 5 6 General Corrosion Additions Plating Stiffeners and Girders End Attachments Buckling

Section 1 General1.1 Application 1.1.1 Scantlings of various platings, stiffeners and girders to meet the local strength requirements are to be determined in accordance with the general principles given in this Chapter. The design values of loads to be considered are given in Ch.4. 1.1.2 Scantlings of hull members contributing to the longitudinal strength are also to comply with the requirements of Ch.5. 1.1.3 Scantlings of hull members subjected to compressive stresses are also to comply with the requirements of Sec.6. 1.2 Symbols p = design pressure [N/mm2] as per Ch.4. s = stiffener spacing [mm], measured along the plating. l =span of the stiffener, [m], in accordance with 4.1.1. r = radius of curvature [mm]. S = span of the girder [m], in accordance with 4.1.2. b = mean breadth [m], of the load area supported by the girder. hw = height of web, [mm]. bf = width of flange, [mm]. tw, tf = net thickness of web and flange [mm], respectively after deduction of tc as given in 2.1.1. For bulb sections, tf is to be based on the mean thickness of the bulb. = allowable bending stress, [N/mm2] as given in the relevant Chapters. y = minimum yield stress of material, [N/mm ], may be taken as 235 [N/mm2] for normal strength steel.2

k = material factor as defined in Ch.2, Sec.1.2. E = modulus of elasticity, 2.06 x 105 [N/mm2] for steel. 1.3 Frame spacing 1.3.1 The normal frame spacing between aft peak and 0.2L from F.P. may be taken as: 450 + 2L [mm] for transverse framing 550 + 2L [mm] for longitudinal framing. However, it is generally not to exceed 1000 [mm].



Part 3 Principles for Scantlings and Structural Details

1.3.2 Elsewhere, the frame spacing is generally not to exceed the following: In peaks and cruiser sterns:

700 [mm] or as in 1.3.1, whichever is lesser. 1.3.3 Where the actual frame spacing is higher than that mentioned above, the minimum thicknesses of various structural members as given in the Rules may require to be increased.

600 [mm] or as in 1.3.1, whichever is lesser. Between collision bulkhead and 0.2L from F.P.:

Section 2 Corrosion Additions2.1 General 2.1.1 The thickness of plates, stiffeners and girders in tanks for water ballast and/or cargo oil and in holds of dry bulk cargo carriers is to be increased by a corrosion addition 'tc' as given in Table 2.1.1. 2.1.2 The required corrosion addition 'Zc' to the section modulus of stiffeners and girders due to the thickness addition 'tc' mentioned above may be approximated as:

Zc =

t c h w (b f + 0.3h w ) [cm 3 ] 1000

Table 2.1.1 : Corrosion addition tc [mm] Item Internal members within and plate boundary between spaces of the given category Plate boundary between the two given space categories Space Category Ballast tank Cargo oil tank only Hold of dry bulk cargo carriers Ballast tank/Cargo oil tanks only Ballast tank/Hold of dry bulk cargo carrier Ballast tank/Other category space Cargo oil tank only/Other category space Hold of dry bulk cargo carrier/Other category space Vertical Surfaces Standard Min-max. 1a) 0.1 tn 2-3 0.1 tn 2-3 0.2 tn 2.54 - 3.5 0.1 tn 0.15 tn 0.05 tn 0.05 tn 0.1 tn 2-3 1a) 2-3 0.5 - 1.0 1c) 0.5 - 1.0 Horizontal Surfaces Standard Min-max. 1a) 0.15 tn 2-4 0.15 tn 2-4 0.2 tn 2.54 - 3.5 0.15 tn 0.15 tn 0.1 tn 0.1 tn 0.1 tn 2-4 1b) 2-4

2-3 2-3

1.5 - 2.0

1.5 - 2.0

Notes: 1 Where the relevant ballast or liquid cargo tanks extend upto the exposed weather deck, the minimum corrosion addition in the region extending upto 1.5 [m] below the weather deck is also to be not less than that indicated below against the symbols 1a, 1b, 1c used in the table. 1a) 3.0 [mm] 1b) 2.0 [mm] 1c) 2.0 [mm] 2 tn = net plate thickness required [mm]. 3 The term ballast tank also includes combined ballast and cargo oil tanks, but not cargo oil tanks which may carry water ballast on exceptional circumstances according to Regulation 13(3) of MARPOL 73/78. 4 Hold of dry bulk cargo carriers refers to the cargo holds of vessels with class notations BC-A, BC-B, BC-C or Ore Carrier. For single skin bulk carriers of length 150 [m], tc min = 3.5 [mm]. 5 Other category space denotes the hull exterior and all spaces other than water ballast and cargo oil tanks and holds of dry bulk cargo carriers.



Section 3 Plating3.1 General 3.1.1 Minimum requirements of thickness of various platings are given in relevant chapters. 3.1.2 The thickness 't' of plating subjected to lateral pressure is not to be less than

=

1.10 0.5(s/1000 l ) 2 ;

however, not to be taken more than 1.0. fr = correction factor for curvature perpendicular to the stiffeners = (1 - 0.5 s/r) 3.1.3 Any tapering of thickness of platings contributing to the longitudinal strength is to be based upon linear variation of stress allowed at specified regions.

s p t=f f + t [mm] a r 2 cwhere, fa = correction factor for aspect ratio of plate field;

Section 4 Stiffeners and Girders4.1 Determination of span be = c. b 4.1.1 For stiffeners, the span 'l' [m] is to be taken as the length of the stiffener between the two supporting members less the depth of stiffener on crossing panel if any. Where brackets larger than those required in 5.1.2 are fitted, the span may be determined as shown in Fig.4.1.1. For curved stiffeners, 'l' may be based on the chord length. 4.1.2 For girders, the span 'S' [m] is to be taken as the length of the girder between the two supporting members, less the web height of inplane girder if any, and the correction for bracket 'bc', as shown in Fig.4.1.2. 4.2 Effective width of attached plating 4.2.1 The area of the attached plating, to be used in the calculation of sectional properties of the stiffeners and girders, is to be taken as the cross-sectional area within the effective width of the attached plating. 4.2.2 The effective width of plating attached to a stiffener may be taken as the mean of spacings on either side of the stiffener. 4.2.3 The effective width of plating attached to a girder, 'be' is to be taken as per the following: where, c = c1, for girders with uniformly distributed loads or with six or more evenly spaced point loads = c2, for girders with three or less evenly spaced point loads. Table 4.2.3 : Values of "c"a/b C1 C2 0.5 0.19 0.11 1.0 0.38 0.22 2.0 0.67 0.40 3.0 0.84 0.52 4.0 0.93 0.65 5.0 0.97 0.73 6.0 0.99 0.78 7.0 1.00 0.80

For intermediate values of a/b and number of point loads, values of 'c' may be obtained by interpolation. a = span of the girder, for simply supported girders, [m]. = 60 per cent of span of the girder, for girders fixed at both ends, [m]. 4.2.4 In case of girders on corrugated bulkheads which run across the corrugations, the effective width of attached plating is to be taken as 10% of that obtained from 4.2.3.






4.2.5 The effective cross sectional area of the attached plating is not to be less than that of the face plate. 4.3 Scantlings of stiffeners 4.3.1 The section modulus 'Z' of stiffeners subjected to lateral pressure is not to be less than:

be taken as 12 for continuous longitudinal girders and 10 for all other girders. 4.4.3 The effective cross sectional area of the girder web is to be taken as : Aw = 0.01 hn tw [cm ] where, hn = net girder height, [mm], after deduction of cutouts at the section under consideration. Where an opening is located at a distance less than hw/3 from the cross section under consideration, hn is to be taken as the smaller of the net height and the distance through the opening (hn1 + hn2) (See Fig.4.4.3).2

Z=

s.p.l 2 .10 3 + Z c [cm 3 ] or 15 [cm 3 ] m

whichever is greater. where, m = bending moment factor depending on the arrangement at the supports and variation of lateral pressure as given in the relevant chapters. Where not stated, the `m' value may generally be taken as: = 12 for continuous longitudinal stiffeners. = 10 for transverse, vertical and non-continuous longitudinal stiffeners fixed at both ends. = 8 for stiffeners simply supported at both ends. 4.3.2 Where stiffeners are not perpendicular to the plating, the section modulus as obtained from 4.3.1 is to be increased by the factor (1/cos ), being the angle between the stiffener web and the plane perpendicular to the plating. 4.4 Scantlings of girders 4.4.1 The scantlings of simple girders subjected to lateral pressure which can be considered as conforming to the general beam theory are to satisfy the requirements given in 4.4.2 and 4.4.3. 4.4.2 The section modulus 'Z' of girders subjected to lateral pressure is not to be less than:

Fig.4.4.3 : Effective web area of girders Where the girder flange is at angle to the length of the girder, Aw may be taken as: Aw = 0.01 hn tw + 1.3 a Sin 2 Sin [cm2] where, a = area of flange, [cm2] The requirement of effective web area of various girders are given in the relevant Chapters. 4.4.4 The thickness of the girder web tw is not to be less than: tw = (6 + 0.02L) + tc [mm] or tw =

b.p.S 2 .10 6 + Z c [cm 3 ] Z= mwhere, m = bending moment factor depending upon the arrangement at supports and variation of lateral pressure as given in the relevant chapters. Where not stated, the 'm' value may generally

Sw + tc [mm], whichever is greater. 55

where, Sw = web depth or spacing [mm], of the first web stiffener parallel to the face plate. In case of




deep girders, value of Sw may be taken as 90% of the actual spacing. The web stiffeners may be flat bars of same thickness as that of the web and 1/10 of the height of girder, in depth. 4.4.5 Where openings are cut in the girder web, they are to be away from the girder ends and scallops for stiffeners; with their centre located as near to the neutral axis of the girder as practicable. Openings of depth exceeding 25% of the girder depth or 300 [mm] and, of length exceeding the depth of the girder or 60% of the secondary stiffener spacing, are to be reinforced all around at the edge; or alternatively by providing horizontal and vertical stiffeners. 4.4.6 Girders are to be provided with adequate lateral stability by tripping brackets fitted generally at every alternate stiffener in case of

asymmetrical section or at every fourth stiffener in case of symmetrical section. Tripping brackets are also to be fitted at the toes of end brackets and in way of concentrated loads such as heels of pillars or cross ties. Where the width of face plate on one side of the web exceeds 15 tf, the tripping brackets are to be connected to the face plate. The tripping brackets are to be adequately dimensioned at base and are to have a smooth transition to the adjoining stiffeners. The free edge of the tripping bracket is to be stiffened if it's length exceeds 60t [mm]. Additional stiffeners are to be fitted parallel to the free edge to ensure that the arm length of an unstiffened triangular end panel does not exceed 100t [mm].

Section 5 End Attachments5.1 End attachments of stiffeners 5.1.1 All stiffeners participating in the longitudinal strength are generally to be continuous over transverse members within 0.5L amidships. Proposals of longitudinals abutting at transverse members may be accepted outside 0.5L amidships region and in ships less than 150 [m] in length, provided the brackets connecting the ends of the longitudinals are continuous and of adequate size. 5.1.2 Scantlings of brackets fitted on stiffeners not participating in the longitudinal strength are not to be less than the following: The arm lengths, 'a and b' (See Fig.4.1.1) are to be such that:

t = (4.0 + 0.3 Z )-

(k b /k s ) + t c [mm]

Thickness of flanged bracket is to be not less than:

t = (3.0 + 0.25 Z )

(k b /k s ) + t c [mm]

but need not be taken greater than 13.5 [mm] Width of flange, w 40 + Z/25 [mm], but not to be less than 50 [mm].

where, Z is the section modulus [cm3], of the smaller stiffener, being connected. kb, ks are the material factors for the bracket and the stiffener, respectively. 5.2 End attachments of girders 5.2.1 The end attachments and supporting structure of the girders are to provide adequate resistance against rotation and displacement of the joint and effective distribution of the load from the member. Supporting members to which the girders are being connected, may require additional strengthening to provide adequate

i) a, b 0.8 lb and ii) a+b 2.0 lb where, lb = 24 -

Z + 75 [mm]

Thickness of unflanged bracket is to be not less than:


Rules and Regulations for the Construction and Classification of Steel Ships - 2011 Page 7 of 10 ___________________________________________________________________________________ stiffness to resist rotation of the joint. Where the end attachment provides only a low degree of restraint against rotation, the girder is generally to be extended beyond the point of support by at least two frame spaces before being gradually tapered. Connections between girders forming a ring system are to be such as to minimize stress concentrations at the junctions. Integral brackets are generally to be radiused or well rounded at the toes. Where the face plate of the girder is not continuous over the bracket, the free edge of the bracket is to be stiffened and the face plate of the girder is to be extended well beyond the toe of the bracket. 5.2.2 The thickness 't' of brackets on girder is not to be less than that of the girder web. The arm length 'a' including the depth of girder is not to be less than:

a = 83 (Z/t) [mm];where, Z = the section modulus [cm3], of the girder to which the bracket is connected. The cross sectional area 'Af' of the face plate on the girder bracket is not to be less than: Af = 0.001 lf t [cm2] where, lf is the length [mm], of the free edge of the bracket. Additional stiffeners parallel to the bracket face plate are to be fitted on webs of large brackets. The arm length of an unstiffened triangular end panel of bracket is generally not to exceed 100t [mm].

Section 6 Buckling6.1 General 6.1.1 The critical buckling stress 'cr' of plate panels and stiffeners and other members to compressive loads is to be such that: = 0.9 for torsional and web buckling mode of longitudinals

=-

cr where,

c

0.7 (need not be taken smaller than 0.3); 1 + l m /ifor axially loaded members such as pillars, cross-ties, panting beams etc., in general. to be reduced by 15 per cent where the loads are primarily dynamic in nature. for 'lm' and 'i' See 6.2.6.

c = compressive stress to be considered as per Sec.6.3 = 1.0 for deck, longitudinally stiffened side shell and single bottom plating = 0.9 for bottom, inner bottom plating in double bottom and transversely stiffened side shell plating = 1.0 for local plate panels where an extreme load level is applied (e.g. impact pressure) = 0.8 for local plate panels where a normal load level is applied = 0.85 for lateral buckling mode of longitudinals

-

6.1.2 The critical compressive buckling stress 'cr' may be determined as follows :

cr = E= y (1 where,

when

E 0.5 y

y ) when E > 0.5 y 4 E

E = ideal elastic buckling stress as per Sec.6.2.




6.1.3 The critical shear stress of plate panels, stiffeners and other members to be such that cr c/ where, c = Actual shear stress calculated for the plate panels The shear stresses in plate panels of side shell and longitudinal bulkheads are given in Ch.5, Sec.4.2. = 0.90 for ship's side and longitudinal bulkhead subject to hull girder shear forces = 0.85 for local panels in girder webs when nominal shear stresses are calculated (c = Q/A) = 0.90 for local panels in girder webs where shear stresses are determined by finite element calculation. 6.1.4 The critical shear buckling stress, 'cr' may be determined as follows:

s 2 = C 1 + 1000 l -

2

2.1 + 1.1

for platings with stiffeners in the direction perpendicular to the compressive stress

= ratio between the smaller and the larger values of the compressive stress assuming a linear variation (See Fig.6.2.1)

cr = E= y (1 where,

when

E 0.5 y

y4 E

C = 1.30 when plating is stiffened by floors or deep girders = 1.21 when stiffeners are angles or T sections = 1.10 when stiffeners are bulb flats

) when E > 0.5 y

E = ideal elastic shear buckling stress [N/mm2], as per 6.2.2. y = yield stress in shear of the material [N/mm2] = y/3. 6.2 Ideal elastic buckling stress 6.2.1 The E value for platings may be taken as:

= 1.05 when stiffeners are flat bars s = shorter side of plate panel, [mm] l = longer side of plate panel, [m] 6.2.2 The ideal elastic buckling stress for plate panels in shear may be taken as: E = 0.9 Ks E [(t - tc)/s]2 [N/mm2] where, Ks = 5.34 + 4 (s/1000 l )2

E = 0.9 K E [(t t c )/s]2 [ N/mm 2 ]where,

8.4 K= + 1.1for plating with stiffeners in the direction of the compressive stress

6.2.3 The value for the lateral buckling mode of longitudinals may be taken as: E = 0.001 E Ia / (A.l2) [N/mm2] where, Ia = moment of inertia [cm4], of the longitudinal about the neutral axis parallel to the plating


Rules and Regulations for the Construction and Classification of Steel Ships - 2011 Page 9 of 10 ___________________________________________________________________________________ A = cross longitudinal sectional area [cm2], of the

In the calculation of Ia and A, attached plating area corresponding to the longitudinal spacing and net thickness is to be included. 6.2.4 The E value for the torsional mode of longitudinals may be taken as:

=-

b 3 h 2 [t f b f2 + 2b f h w + 4h 2 + 3t w b f h w ]10 6 f w w 12 (b f + h w ) 2for angles and bulb profiles

(

)

C = spring stiffness exerted by supporting plate panel

E =

It K 2 2 m + 2 + 0.385 E [N/mm ] Ip 10 I p l m 2 4 2

E Iw

=

(3 s t

k pE t3 t3 p w3 w

+ 4k p h w t 3 p

)

where,

K=

Cl 4 10 6 4 E Iwwaves

kp = 1 - p, not to be taken less than zero; and for flanged profiles need not be taken less than 0.1. tp = net plate thickness, [mm], after deduction of 'tc' as given in 2.1.1.

m = number of deformation half depending on K, as per Table 6.2.4.

p =

It = St Venant's moment of inertia, [cm4], of profile (without plate flange)

c Epstress for

=

hw tw 10 4 for flat bars (slabs) 3 4 10

3

c = calculated compressive longitudinals as per Sec.6.3.

Ep = elastic buckling stress of supporting plate calculated as per 6.2.1. 6.2.5 The E value for the web buckling mode of longitudinals may be taken as :

t 3 = 1 h w t 3 + b f t f 1 0.63 f w 3 bf for flanged profiles

Ip =polar moment of inertia, [cm4], of profile about connection of stiffener to plate

t E = 3.8E w h w

[N/mm 2 ]

2

=

h t w 4 10 for flat bars (slabs) 3

3 w

Buckling of flanges on angles and T-sections of longitudinals is taken care of if the as built flange thickness is not less than 1/15 of the flange width on one side of the web. 6.2.6 The E value for axially loaded members may be taken as: E = 0.001 C E (i / lm)2 [N/mm2] C = 1.0 for both ends hinged = 2.0 for one end fixed = 4.0 for both ends fixed

h3 t = w w + h 2 b f t f 10 4 for flanged profiles w 3 Iw = sectorial moment of inertia, [cm ], of profile about connection of stiffener to plate6

=

h3 t 3 w w 10 6 for flat bars (slabs) 36

=

t f bf h 2 w 10 6 for ' Tee' profiles 12

3




Table 6.2.4 0 350 [m] ao = common acceleration parameter

=

3C w C v V + L L

where,

Cv =

L for L < 100 [m] 50

= 0.2 for L 100 [m] 1.2.2 For ships with service limitations, the wave bending moments and shear forces and the dynamic components of external sea pressures are to be reduced by application of the reduction factor 'Rs' as given below: Rs = 1.0 for unrestricted service = 0.75 for coastal service = 0.65 for restricted service = 0.55 for sheltered water service. For definitions of service limitations, see Pt.1 Ch.1.

p = design pressure [N/mm2] Cw = 0.0856L for L 90 [m] = 10.75 - [(300-L)/100]3/2 for 90 < L< 300 [m] = 10.75 for 300 L 350 [m]



Part 3 Design Loads

Section 2 Ship Motions and Accelerations2.1 Roll and pitch angles where, 2.1.1 The values of single amplitudes of roll and pitch angles (corresponding to their periods Tr and Tp respectively), are normally to be taken as: - The roll angle, = where, c = (1.25 - 0.025 Tr) d d = 1.2 for ships without bilge keel = 1.0 for ships with bilge keel having area equal to 2.5% of LxB For other percentages of bilge keel areas 'd' is to be interpolated. Tr is not to be taken greater than 30 [s] = roll angle as given in 2.1.1 Tr = period of roll. [s]. = ( 2kr / GM ) kr = roll radius of gyration, [m]. GM = metacentric height, [m]. Minimum value of Tr resulting from various possible combinations of kr and GM is to be used. In case detailed calculations for kr and GM have not been carried out, the following values may be used. kr = 0.39B for ships with even transverse distribution of mass = 0.35B for tanker in ballast = 0.25B for ships loaded with ore between longitudinal bulkheads. GM = 0.07B Rr = distance from the centre of the mass under consideration to the axis of rotation, [m]. The axis of rotation for roll may be taken on the centre line of the ship and at a height 'z' above base line where,

50 c [radians] B + 75

ao - the pitch angle, = 0.25 [radians] Cb2.2 Acceleration components 2.2.1 The design values of various acceleration components are normally to be taken as : - the surge acceleration, ax = 0.2 goao Cb [m/s2] - the combined sway/yaw acceleration ay = 0.3 go ao [m/s2] - the heave acceleration

D T z = + [m] or, 4 2=whichever is smaller. the radial roll acceleration may normally be neglected.

az =

0.7g o a o Cb

[m/s 2 ]

D [m] 2

- the tangential roll acceleration, (excluding gravity)

2 a r = R r [m/s 2 ] Tr

2

The tangential pitch acceleration, (excluding gravity):



2 a p = R p [m/s 2 ] Tp where, = pitch angle as given in 2.1.1

2

-

av may be approximated as

av = kvwhere,

goa o [m/s 2 ] Cb

Tp = 1.8

kv = 1.3 aft of A.P.

(L/g o ) [s]

= 0.7 between 0.3L and 0.6L from A.P. = 1.5 forward of F.P. Between these specified regions kv may be obtained by linear interpolation. the combined transverse acceleration, (combined effect of sway, yaw & roll )

Rp = distance from the centre of the mass under consideration to the axis of rotation [m].The axis of rotation for pitch may be taken at 0.45L from A.P. and 'z' [m] above base line. the radial pitch acceleration may normally be neglected.

2.3 Combined accelerations 2.3.1 The combined accelerations in the ship's vertical, transverse, and longitudinal directions are to be taken as: the combined vertical acceleration (combined effect of heave, pitch and roll; excluding gravity)2 2 (a z + a 2 + a pz ) [m/s 2 ] rz

at =where,

[ a + (g Sin + a ) ] [m/s ]2 y 2 2 o ry

ay = sway/yaw Sec.2.2.1

acceleration

as

given

in

av =where,

ary = transverse component of tangential roll acceleration given in Sec.2.2.1, the same may be obtained by using in the formula the vertical projection of the distance Rr instead of Rr. the combined longitudinal acceleration, (combined effect of surge and pitch)

az = heave acceleration as given in 2.2.1 arz = vertical component of the tangential roll acceleration as given in 2.2.1 apz = vertical component of the tangential pitch acceleration as given in 2.2.1. It may be noted that the components arz and apz may be obtained from the formulae given in 2.2.1 using the horizontal projections of the distances Rr and Rp instead of Rr and Rp respectively.

al =where,

[a + (g Sin + a ) ] [m/s2 x 2 o px

2

]

ax = surge acceleration given in 2.2.1 apx = longitudinal component of the tangential pitch acceleration given in 2.2.1, the same may be obtained by using in the formula the vertical projection of the distance Rp instead of Rp.



Part 3 Design Loads

Section 3 Design Pressures and Forces3.1 General 3.1.1 The scantlings of shell and weather deck panels are to be based upon the external sea pressures given in Sec.3.2, or internal pressure, in way of tanks as given in Sec.3.3 if these be greater. While determining internal pressures on shell panels, external sea pressure at ballast draught given in 3.2.4 may be deducted. Inner bottoms, decks and hatch covers supporting dry cargo, stores and accommodation spaces are to be based upon design pressures given in Sec.3.4. The gravity and acceleration forces from heavy units of cargo and equipment which may influence scantlings are given in Sec.3.5. 3.1.2 The design pressures are to be calculated at the loadpoint which is defined for various strength members as follows. Loadpoint for plates ks = 6 aft of A.P. midpoint of horizontally stiffened plate field half the

part 3

Documents

general section

scantlings section

longitudinal section

symbols section

stress section

stability section

board section

loading chapter