LNG Carriers Ship Life Extension. Ed Waryas. Lloyd s Register North America, Inc.

Transcription

1 LNG Carriers Ship Life Extension Ed Waryas Lloyd s Register North America, Inc.

2 Longevity Study - Outline Owners Records Classification Records Ship inspection RAM Study Structural Integrity Analysis

3 Owner s Records Owners records Classification Records Shipboard Records

4 Ship Inspection Single Ship or Fleet Voyage During Refit

5 Hull Structure External Hull Water Ballast Tanks Thickness Measurements Paint coatings

6 Machinery Redundancy Main Engine Boilers Auxiliaries Pumps & Piping

7 Electrical Alternators Switchboards Cabling Motors Control & Alarm Systems

8 Cargo Systems Containment Cargo Pumps Piping Auxiliaries

9 RAM Study (Reliability, Availability, Maintainability) The RAM study - provides information on future fleet performance and availability Trade Feasibility Utilization

10 RAM Study The Task The Method Data Simulation Input - Validation Simulation Output Conclusions

11 THE TASK Assess the capacity of an LNG carrier/fleet to maintain existing availability over the 20 year life extension period. Identify performance critical systems. Availability?

12 THE METHOD SYSTEM DATA AND FUNCTION INFORMATION COLLECTION. SYSTEM ANALYSIS WITH MARINE TRADE EXPERT INPUT. IDENTIFICATION OF SHIP, FLEET AND TRADE CRITICAL SYSTEMS. FLEET DATA INPUT RUN FLEET ENOUGH TIMES OVER PERIOD REQUIRED TO GIVE CONFIDENCE. AGREE DATA AND PROCESSES FOR SYSTEM MODEL WITH CLIENT. ANALYSIS OF RAM DATA FOR CRITICAL SYSTEMS AND FUNCTIONS. VALIDATION OK DERIVE PROBABILITY OF LOSS OF CRITICAL SYSTEMS, FUNCTION & TRADE TARGETS. REVIEW RESULTS WITH CLIENT. DISCUSS VARIATIONS IN CONFIGURATION AND OPERATING POLICY.... UNTIL IF OPERATING POLICY IS INADEQUATE, REVIEW MAINTENANCE POLICY THROUGH APPLICATION OF RELIABILITY CENTERED MAINTENANCE TECHNIQUES. CLIENT ASSESSMENT OF RISK AND COST ACCEPTABLE.

13 DATA - RECORDS Company records Supported by LR s own database For a five year period typical data indicates: Availability 97.11% Dry-dock 2.25% Delays 0.64%

14 DATA - TRADE LNG cargo lifts from load ports Regas delivery points (Analysis of vessel trading routes)

15 SIMULATION INPUT - VALIDATION Trade detail Seasonal weather detail Ship critical system RAM data Ship capacity Operating rules Ship and fleet speed control

16 SIMULATION OUTPUT The following typical results can be derived: Data Analysis FLEET modeling Delay based Net Availability 97.1% 96.1%

17 Typical Conclusions Trade expansion may be limited. Enhanced maintenance actions and data recording will improve performance. Fleet utilisation is low - RAM performance does not affect the current trades.

18 Structural Integrity Analysis The main purpose of the Structural Integrity Analysis is to compliment the inspections, which establish the current condition and past record, by calculating the likely future structural performance of key components. From this, key structural components which may require repair or modification over the extension period can be identified.

19 Structural Integrity Analysis The three principal components are: wave loading evaluation of hull structure evaluation of cargo containment system

20 Wave Loading Determination of long term wave loading, ship motions and accelerations for specified trading routes in full load and ballast conditions at typical operational speeds

21 Hull Structure Investigation consists of two levels: strength and fatigue of hull girder finite element modelling to establish detail stresses at critical connection points

22 Fatigue of hull longitudinals at typical transverse bulkhead

23 Hull Structure - finite element analysis To determine stresses and stress concentrations at typical hull details, e.g. hopper connections trunk deck endings double bottom girder / transverse bulkhead connection

24 Finite Element Model

25 Ballast Hogging Condition Inner Hull and Deck Stresses

26 Stresses at Detail : Hopper Knuckle

27 Fatigue analysis of cargo tank membranes Analysis examined, for N. Atlantic - primary membrane strake end connections secondary membrane chair washer pipe tower base support to primary membrane trihedron connections to primary membrane

28 Typical Conclusions Steel hull structure - Providing maintenance continues, and structural repairs performed, then hull integrity can be assured over proposed total ship life of 40 years. Cargo tank membrane system - The membrane system could be expected to perform satisfactorily for the proposed 40 year life.