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American Bureau of Shipping Introduction To ABS Rules

American Bureau of Shipping Introduction To ABS Rules. Presentation t o the Naval Academy 6 April 2005. What is Classification?. Classification is third party certification in the marine industry. Classification is a process which certifies adherence to a recognized set of technical

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American Bureau of Shipping Introduction To ABS Rules

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  1. American Bureau of ShippingIntroduction To ABS Rules Presentation to the Naval Academy 6 April 2005

  2. What is Classification? Classification is third party certification in the marine industry Classification is a process which certifies adherence to a recognized set of technical standards, representing that a ship or other type of marine structure is structurally sound and mechanically fit for its intended purpose.

  3. The Classification Process Develop Technical Standards (Rules) Developed through industry-based technical committee structure Embraces recognized external standards Updated annually Customized when necessary (new technology/new application) Implement Technical Standards Design Plan review and engineering analysis Survey during construction Periodic survey throughout vessel life

  4. MODU Rules High Speed Craft Guide Redundant Propulsion Guide SWATH Guide Steel Vessel Rules The Classification Process Rules and Guides Rules are the foundation of the process Over 60 sets of Rules and Guides Developed with industry Naval Vessel Rules Industry Committee Based Peer review from all relevant parties Continual feedback and update Calibrated to proven experience

  5. ABS - a Snapshot world leader in ship safety and environmental protection since 1862 1500 people 225 offices 81 countries ISO 9000 certified 60+ Rules and Guides 10,000 ships in class (250+ Government) totaling over 100 million gross tons 20,000 manhours engineering review per month 708 new construction ships under survey (15 million gross tons) A Industry and Government Involved in Management and Operations

  6. Engineering Group • OED - Offshore Engineering Department • AA - Advanced Analysis Department • SED - Ship Engineering Department • Materials & Welding Department • Naval Engineering Department

  7. Ship Engineering Department • Tanker / Bulk Carrier / Ship Safety Group • General Cargo Ship Group • Tonnage • Load Line Stability Group

  8. ABS Rules • Steel Vessel Rules • Steel Barges - Ocean Service Barges of any Length • Steel Vessels Under 90 m - Crewboats, Tugs • High Speed Naval Craft- Patrol Boats HSVs • Steel Vessels for Service on Rivers, ICW - River Barges, Towboats • Bulk Carriers for Service on the Great Lakes - Freshwater Operations • Reinforced Plastic Vessels - F. R. P. Vessels • Aluminum Vessels - Aluminum Commercial Vessels 100’ - 500’ • Naval Vessel Rules • MODU - Mobile Offshore Drilling Units

  9. ABS Guides • Motor Pleasure Yachts - Steel, Aluminum, or FRP • High Speed Craft, - Commercial/Government Service Planing vessels • Fishing Vessels - Steel Fishing Vessels Under 90 m (200’) • Offshore Racing Yachts - Steel, Aluminum, or FRP Sailing Vessels • Fire Fighting Vessels - Steel Fireboats • Crew Accommodations Guide • Oil Recovery Vessels - Oil Spill Cleanup Vessels • Floating Production Storage and Offloading Vessels - (FPSO) • Small Waterplane Area Twin Hulled Vessels - (SWATH)

  10. Ship Acquisition Process MNS ORD A-Spec Requirement Derivation RULES B-Spec Optional Step C-Spec Build-to- Print Owner Contractor Technical Validation CLASSIFICATION

  11. Function - Fitness - Safety Owner’s Requirements not addressed elsewhere mission related owner unique Detailed Component and Performance Standards Statutory Compliance safety of life issues environmental protection Classification Rules structural and mechanical fitness physical attributes of ship Baseline Technical Standards

  12. Hull Classification Considerations • Intact and Damaged Stability • Specialized Vessel Criteria • Freeboard Assignment • Strength of Hull Structure • Longitudinal Strength Requirements • Local Strength Requirements • Condition Assessment • Surveys During Construction • Surveys In-Service

  13. Structural Analysis 1. Load Determination - “What are the Loads?’ 2. Response Determination - “How do these loads affect the Structure?” 3. Strength Evaluation - “Are the structural arrangements and materials adequate for the determined response?”

  14. Ship Structure • Longitudinal Strength (Continuous Members) • Local Plating/Stiffener Requirements • Main Supporting Members • Longitudinal/Transverse Bulkheads • Web Frames • Appendages • Rudder/Skeg • Bilge Keel • Materials • Grade ( Strength & Toughness ) • Castings / Forgings • Welding

  15. Longitudinal StrengthUnified IACS Requirement • Still Water Bending Moment • Wave Bending Moment • Hogging Condition • Sagging Condition • Total Bending Moment

  16. Strength Evaluations • Material Selection • Grade (Strength vs. Toughness) • Castings/Forgings • Welding • Service Temperature • Thickness • Failure Modes • Yielding • Buckling • Fatigue • Fracture

  17. Fatigue Assessment • Description of the Environment • Calculations of Ship Motions, Sealoads, and Local Hydrodynamic Pressures • Calculations of Structural Response and Stress Transfer Function • Selection of Appropriate S-N Curves and Stress Concentration Factors • Estimation of Fatigue Life and Comparison with Acceptance Criteria

  18. Semi–Empirical Approach to Hull Classification Longitudinal Strength Yielding (Explicit) P Buckling (Both) Analysis Local Strength Response Determination Fatigue (Implicit) Fracture (Implicit) Main Supporting Members Material Requirements Strength vs. Toughness

  19. Semi-Empirical RulesDerived from First Principles • Stiffeners (beams) • Assume Fixed End Beams where M = wl2 / 12 • w = s h & SM= M / Fb • Allowable Stress Fb = 15.68 KSI or 20.16KSI for Ordinary Steel Fy =34KSI • ABS Rule • SM= ,0041 c h s l2

  20. Safehull Project Objective“ A Completely Restated Set of Hull Design and Evaluation Criteria” • Establish Loads and Combinations Acting on the Global and Local Structure • Specify the Extent and Types of Analyses Required to Determine Loads • Establish the Required Strength of the Structure to Resist Load Effects

  21. Traditional Approach • Nominal Loading - Prescribed • Simple Design Equations in Rules • Calibrated by Satisfactory Service Experience

  22. Modern Approach • Expected Loading - Calculated • Analysis Methods to Establish Load Effects • Strength Performance Criteria Under Demands of Loads

  23. Net Ship Approach • Design Strength is Evaluated with Expected Corrosion Values Removed • Nominal Strength can be Preserved for the Entire Life of the Vessel • Appropriate Corrosion Margins can be added to Accommodate Longer Design Lives • Allows Explicit Means to Assess Sensitivity of Structural Strength to Corrosion

  24. Net Ship Concept • Corrosion • Fatigue • Corrosion/Fatigue Interaction

  25. Corrosion Margins Recommended Corrosion Location/Structural Element Margin for Class (mm)* Cargo Tank Ballast Tank Effectively Coated Deck Plating 1.0 2.0 Side Shell Plating N.A 1.5 Bottom Plating N.A 1.0 Innerbottom Plating 1.5 1.5 Longitudinal Bulkhead Plating 1.0 1.5 Transverse Bulkhead Plating 1.0 1.5 Transverse & Longitudinal Deck Supporting Members 1.5 2.0 Double Bottom Tank Internals (Stiffeners, Floors and Girders) N.A 2.0 Vertical Stiffeners and Supporting Members Elsewhere 1.0 1.0 Non-vertical Longitudinals/Stiffeners and Supporting Members Elsewhere 1.5 2.0

  26. Load ComponentsDetermined Through Parametric Seakeeping Analysis • Hull Girder Loads • Still Water and Wave Induced Bending Moment and Shear Force • Vertical, Horizontal and Torsional • Internal Tank Pressure • Added Pressure Head due to Roll and Pitch • Internal Forces due to Accelerations • Sloshing • External Pressure • Hydrostatic Pressure Distribution • Wave Induced Dynamic Pressure Distribution

  27. Load Determination • North Atlantic Route • Strip Theory for Response • Probabilistic Approach • Long Term Values Incorporating: • Wave Spectra • Ship Headings • Service Speed

  28. Summary of Criteria Features • Format • Loads • “Net-Ship” Concept • Strength Criteria • Fatigue Criteria • Analysis to Obtain Load Effects

  29. Finite Element Analysis(Phase B) • 3-Dimensional - Determine Global Loads and Boundary Conditions • 2-Dimensional - Determine Local Stress and Deflections • Yielding • Buckling • Fatigue

  30. Naval Vessel Rules • Derived from Gen Specs and Design Data Sheets • Requires Analysis of Longitudinal Strength using DDS 100 and SPECTRA Program • Requires a FEM Analysis • Uses Prescribed Loads from Traditional Navy Criteria and Specific Design Loads • Concern over Shock Load & Ship Weight

  31. High Speed Naval Craft • Based on Design Criteria from NSWC- CD Combat Craft Department and NAVSEA • Determines Loads from Vessel Response to Sea State, Speed and Heading • Calculate local Slam pressures and Slam Moments • Combines Slam Moment with Hull Girder Bending Moments

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