Hull girder fatigue strength of corroding oil tanker

2010 ◽  
pp. 149-154
Author(s):  
J Parunov ◽  
K _iha ◽  
P Mage ◽  
P Juri_i_
Keyword(s):  
Fatigue Strength ◽  
Hull Girder ◽  
Oil Tanker

Hull-Girder Reliability of a Chemical Tanker

2009 ◽  
Vol 46 (04) ◽  
pp. 192-199
Author(s):  
Jôsko Parunov ◽  
Maro Corak ◽  
C. Guedes Soares
Keyword(s):  
International Association ◽  
Progressive Collapse ◽  
Bending Moment ◽  
Single Step ◽  
Hull Girder ◽  
Structural Rules ◽  
Term Operation ◽  
Reliability Method ◽  
Reliability Bound ◽  
Oil Tanker

The aim of the paper is to calculate hull-girder reliability of chemical tanker according to the reliability model proposed by International Maritime Organization (IMO). The probability of hull-girder failure is calculated using a first-order reliability method for two operational profiles—one typical for oil tanker and the other one modified in order to reflect differences between oil tanker and chemical tanker. The evaluation of the wave-induced load effects that occur during long-term operation of the ship in the seaway is carried out in accordance with International Association of Classification Societies (IACS) recommended procedure. The stillwater loads are defined on the basis of a statistical analysis of loading conditions from the loading manual. The ultimate collapse bending moment of the midship cross section, which is used as the basis for the reliability formulation, is evaluated by progressive collapse analysis and by single-step procedure. The reliability analysis is performed for "as-built" ship and for "corroded" ship according to corrosion deduction thickness from new Common Structural Rules for double-hull oil tankers. It is shown that hull-girder failure probability of "as-built" chemical tanker is well above the upper reliability bound proposed by IMO, while the "corroded" ship is slightly unconservative since the reliability index is lower than IMO lower reliability bound.

The BP Oil Tanker Structural Monitoring System

1995 ◽  
Vol 32 (04) ◽  
pp. 277-296
Author(s):  
David J. Witmer ◽  
Jack W. Lewis
Keyword(s):  
Monitoring System ◽  
Structural Damage ◽  
Prolonged Exposure ◽  
North Pacific Ocean ◽  
The United States ◽  
Management Program ◽  
Structural Monitoring ◽  
Hull Girder ◽  
Response Data ◽  
Oil Tanker

BP Oil Company time-charters a fleet of American-flag tankers for the ocean transportation of crude oil and petroleum products to the East, West and Gulf Coasts of the United States. Commencing in 1991, ship response and structural monitoring instrumentation was installed on the four ships of the Atigun Pass-class. These crude carriers are operated in the Trans-Alaska Pipeline Service, or "TAPS" trade, sailing the waters of the North Pacific Ocean and Gulf of Alaska. The structural monitoring systems were designed to measure the effects of subjecting a ship to the typical loads and forces encountered while at sea: hogging, sagging, slamming, hydrostatic pressure, and hull girder springing. Additionally, BP was interested in developing a system that could provide shiphandling guidance to the master or watch officer so that the detrimental effects of prolonged exposure to such loads and forces could be effectively minimized. The paper describes in detail the physical arrangement of the BP Oil Tanker Structural Monitoring System (BPSMS), including the suite of sensors employed to measure ship responses and hull girder stresses. It explains how the response data collected by the sensors is analyzed by the onboard computer located on the ship's bridge and how ship response data are presented back to the deck officers via a family of display monitor screens. These displays provide the officers with a "tool" that can be used to effectively monitor the physical and structural response of their ship to waves, and to quantify, in terms of lowering the wave bending moment and reducing the risk of slamming, the result of an action or actions taken to minimize the risk of incurring structural damage. Onboard ship response and structural monitoring is now an integral part of BP's tanker fleet structural management program. The units have greatly increased the awareness of the ship's officers regarding their role in helping to control the amount of structural damage done to the ships. Data from the units have also helped management make more informed decisions regarding operational requirements placed on the ships.

A Hydraulic Absorber for Wideband Vibration Reduction in Ship Hulls

1994 ◽  
Vol 116 (1) ◽  
pp. 43-48 ◽  
Author(s):  
W. J. Hsueh ◽  
Y. J. Lee
Keyword(s):  
Vibration Reduction ◽  
Stochastic Theory ◽  
Optimal Level ◽  
Hull Girder ◽  
Ship Hulls ◽  
Optimal Theory ◽  
Hydraulic Servo ◽  
Efficient Level ◽  
Oil Tanker ◽  
Multi Mode

A vibration reduction of ship hulls by an active absorber system is proposed. In the scheme, a tuned mass is moved according to the hull vibration as measured by a multi-mode sensing system in order to generate a suitable active force for vibration reduction of hull girder. In order to supply the large amount of required power, a hydraulic servo system is implemented. Then the dynamic characteristic of the hydraulic system is considered for system design. Based on stochastic theory and optimal theory, the control law of the system is derived in order to approach the optimal level of vibration reduction. A 10-t absorber is applied to a 87,000-t oil tanker to demonstrate the feasibility of this scheme. The results show that the multi-peak values of resonance are suppressed in frequency response. Moreover, the vibration excited by propeller and engine is reduced to an extremely efficient level by this scheme.

Rapid Assessment of Hull Girder Collapse for Corroded Double Hull Oil Tanker After Collision

2016 ◽  
Author(s):  
Sung Hwan Noh ◽  
Jung Kwan Seo ◽  
Jeom Kee Paik ◽  
Samy A. M. Youssef
Keyword(s):  
Finite Element ◽  
Structural Damage ◽  
Rapid Assessment ◽  
Probabilistic Approach ◽  
Hull Girder ◽  
The Alps ◽  
Oil Tankers ◽  
Double Hull ◽  
Oil Tanker ◽  
Probability Density Function Pdf

Corroded tankers might be subjected to a very serious structural damage if involved in collision accidents. For understanding or preventing the collision accidents, various studies are being proposed by researchers to improve the analysis method. In this paper, four types of double hull oil tankers (Panamax, Aframax, Suezmax and VLCC) are used. Probabilistic approach is used to create ship-ship collision scenarios for each target structure and the ultimate longitudinal hull girder strength of the hypothetical oil tanker’s hull cross-section. The ALPS/HULL is used to simulate and is intelligent supersize finite element method (ISFEM) software. A relevant probability density function (PDF) is introduced using the results from finite element simulations of the ship-ship collisions, which is commonly used to predict residual strength.

Influence of Nonsymmetric Steel Sandwich Panel Joints on Response and Fatigue Strength of Passenger Ship Deck Structures

2017 ◽  
Vol 33 (02) ◽  
pp. 135-143
Author(s):  
Jani Romanoff ◽  
Sören Ehlers ◽  
Heikki Remes
Keyword(s):  
Fatigue Strength ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Local Stress ◽  
Element Model ◽  
Design Criterion ◽  
Hull Girder ◽  
Notch Stress ◽  
Panel Stiffness ◽  
Passenger Vessel

Present paper investigates the factors contributing to the stress response of steel sandwich panel deck joints when applied into the hull girder of modern passenger vessel. The emphasis is put on the fatigue analysis, which is the critical design criterion in application of these structures to ships. Two types of joints are considered, i.e., a symmetrical and a nonsymmetrical prismatic joint with respect to the geometrical midplane of the sandwich panel. Stiffness properties are derived for the joints in order to enable the modeling of sandwich structures as part of the hull girder finite element model. The influence of sandwich joints to hull girder response is studied. Notch stress analysis is used for the fatigue strength estimation. The applicability of notch stress method for steel sandwich panels is validated with experiments. The investigation shows that the fatigue strength of steel sandwich panels does not depend only on local stress concentration factors at details, but also on the global stiffness of the structural hull girder system, the sandwich panels, and thus the joint response must be taken into account.

Hull-Girder Reliability of an Aged Oil Tanker

2008 ◽  
Author(s):  
Josˇko Parunov ◽  
Paulo Mage ◽  
C. Guedes Soares
Keyword(s):  
Transfer Functions ◽  
International Association ◽  
Single Step ◽  
Hull Girder ◽  
Structural Rules ◽  
Term Operation ◽  
Strip Theory ◽  
Reliability Method ◽  
Years Of Service ◽  
Oil Tanker

The aim of the paper is to assess the hull-girder reliability of an existing single-hull oil tanker after 25 years of service using a reliability method and assumptions very similar to those proposed recently by International Maritime Organization (IMO). The evaluation of the wave-induced load effects that occur during long-term operation of the ship in the seaway is carried out in accordance with the International Association of Classification Societies (IACS)-recommended procedure, while transfer functions are calculated using the linear strip theory. The still-water loads are defined on the basis of statistical analysis of data recorded on single-hull oil tankers. The ultimate collapse bending moment of the midship cross section, which is used as the basis for the reliability formulation, is evaluated by progressive collapse analysis and by a single-step procedure according to Common Structural Rules (CSR). The reliability analysis is performed for three states of the hull: as built ship with scantlings of the new ship, CSR corroded state with net thicknesses of the structural members according to the corrosion deduction thickness proposed by CSR and survey state with scantlings according to the thickness measurements after 25 years of service. The yearly probability of structural failure is calculated using the first-order reliability method, while sensitivity analysis and a parametric study are performed to investigate the variability of the results with changes of the random variables within their plausible ranges. Results of the analysis are compared with recommended target reliability indices proposed by IMO and also with the results of the reliability assessment of the new double-hull tanker. Such comparison is possible since similar reliability methods and uncertainty models are employed. Results of the analysis may have several useful applications related to the decision-making aspects of the future of an aged oil tanker.

Conditional Risk Assessment Considering Hull Girder Failure of Vessels With Collision-Induced Damage Amidships

2011 ◽  
Author(s):  
Huirong Jia ◽  
Torgeir Moan
Keyword(s):  
Risk Assessment ◽  
Failure Probability ◽  
Load Condition ◽  
Sea State ◽  
Hull Girder ◽  
Collision Event ◽  
Conditional Risk ◽  
Double Hull ◽  
The Given ◽  
Oil Tanker

This paper deals with conditional risk assessment considering hull girder failure of damaged vessels. Only damages amidships are investigated. Conditional risk in this paper is defined as the probability of a given damage multiplied by the probability of hull girder failure conditioned upon the given damage. Taking a double hull oil tanker at full load condition as an example, the 3-hour’s failure probabilities conditioned upon damage properties are estimated. The statistical database for collision event in the HARDER project is adopted to assess the probability of sea state and damage. The sensitivity of 3-hour’s failure probability to the sea state and damage properties is investigated. Furthermore, the conditional risk is also assessed.

The Effect of Sloshing in Tanks on the Hull Girder Bending Moments and Structural Reliability of Damaged Vessels

2012 ◽  
Vol 56 (01) ◽  
pp. 48-62
Author(s):  
Huirong Jia ◽  
Torgeir Moan
Keyword(s):  
Failure Probability ◽  
Structural Reliability ◽  
Bending Moments ◽  
Multimodal Approach ◽  
Coupled Motion ◽  
Rectangular Shape ◽  
Hull Girder ◽  
Set Up ◽  
Oil Tanker ◽  
Damaged Vessel

The structural reliability analysis of damaged vessels has commonly been conducted by neglecting the effect of sloshing. In this paper, the coupled motion of the damaged vessel and sloshing is set up based on the assumption that the damaged tanks are of rectangular shape. The sloshing effects in tanks are modeled by a linear multimodal approach. Then the effect of sloshing in tanks on the hull girder bending moments and the failure probability are studied for an oil tanker in various damage conditions. It is concluded that in certain tank resonance conditions, sloshing effects cannot be neglected. In such cases sloshing damping plays an important role on the sloshing effects.

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