HSLA Naval Grade Steel Failure Investigation in Marine Environment Under Ship Hull Operational Conditions

2021 ◽  
Author(s):  
Arwa Toumi ◽  
Chokri Boubahri ◽  
Jalel Briki ◽  
Haythem Barrek ◽  
Ahmed Hichem Hamzewi
Keyword(s):  
Marine Environment ◽  
Ship Hull ◽  
Operational Conditions ◽  
Failure Investigation ◽  
Grade Steel

Burst Failure and Reliability Assessment of X-100 to X-120 Ultra-High Strength Pipes

2021 ◽  
Author(s):  
U. Bhardwaj ◽  
A. P. Teixeira ◽  
C. Guedes Soares
Keyword(s):  
Structural Reliability ◽  
Limit State ◽  
High Strength ◽  
High Grade ◽  
State Variables ◽  
Operational Conditions ◽  
Statistical Measures ◽  
Reliability Method ◽  
Grade Steel ◽  
State Functions

Abstract The burst failure and the structural reliability of ultra-high strength (X-100 to X-120) steel pipelines is investigated analytically based on their elastic-plastic collapse behaviour. Structural models for high strength pipes and codes are adopted from literature and their key features are discussed. The models are verified by burst test data for ultra-high-grade steel pipelines. Two statistical measures are used to compare the accuracy of models for ultra-high strength steel pipes. The most accurate theoretical model for ultra-high strength pipes is identified. Limit state functions are formulated based on the strength models for reliability analysis of ultra-high-grade steel pipelines under operational conditions. Probabilistic models are applied to the basic variables of limit state functions. A First-Order Reliability Method is used to assess the reliability for this category of pipelines followed by a sensitivity analysis that identifies the most significant limit state variables. The results of this study can provide vital measures for design and maintenance planning of ultra-high-grade steel pipelines.

Different Methods of Refloating a Ship

2013 ◽  
Vol 837 ◽  
pp. 792-797 ◽  
Author(s):  
Anastasia Varsami
Keyword(s):  
Marine Environment ◽  
Cleaning Process ◽  
Shipping Industry ◽  
Maritime Industry ◽  
Operational Conditions ◽  
Basic Understanding ◽  
Hull Damage ◽  
General Opinion

In the shipping industry it is vital for a ships construction to take into consideration any grounding event that might occur, due to the fact that grounding has been representing an important issue in the maritime industry being almost always connected to a catastrophic pollution of the marine environment. Another important matter it is represented by the refloating methods that should be applied on these ships that are grounded, in order to safely take them out of their position with minimum hull damage and no pollution to the marine environment. There is a need for a basic understanding of the geometry, stability and strength of intact ships before trying to refloat a damaged, grounded or sunken ship. When talking about refloating a grounded ship, it is first of all necessary to fully understand the grounded event that led the ship into that position so that the best method for refloating to be applied. It is an important demand to establish the appropriate method of refloating so that the risk of polluting to be reduced at minimum. It is really vital to have a well thought-out and organized salvage plan in order to apply a certain refloating operation. In order to have such a salvage plan it is necessary to investigate properly the ships site and gather the appropriate information. Operational conditions around the ships site, namely the casualty, are dynamic and may change several times throughout the course of the refloating operation and this way many of the refloating operations cannot be applied on that certain cases of grounding. Ships groundings can have devastating effects on the marine environment. Cleaning up after a major grounding event could lead to enormous amounts of money and even then there is no certainty that the cleaning process has the best results or even the wanted ones. The general opinion of the shipping industry is that the cheapest method to refloat a grounded ship is to use the means present onboard that particular ship (means of propulsion, rudder, ballasting/de-ballasting operations, getting rid of weights). In this paper I tried to show how a ship can or cannot use the means present onboard in order to put herself out of the grounding position. In order to do that I have used Transas Navi Trainer 5000 simulator.

Pitting Degradation Modeling of Ocean Steel Structures Using Bayesian Network

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Jyoti Bhandari ◽  
Faisal Khan ◽  
Rouzbeh Abbassi ◽  
Vikram Garaniya ◽  
Roberto Ojeda
Keyword(s):  
Bayesian Network ◽  
Structural Steel ◽  
Marine Environment ◽  
Pitting Corrosion ◽  
Steel Structures ◽  
Poor Quality ◽  
Real World Data ◽  
Corrosion Depth ◽  
Operational Conditions

Modeling depth of long-term pitting corrosion is of interest for engineers in predicting the structural longevity of ocean infrastructures. Conventional models demonstrate poor quality in predicting the long-term pitting corrosion depth. Recently developed phenomenological models provide a strong understanding of the pitting process; however, they have limited engineering applications. In this study, a novel probabilistic model is developed for predicting the long-term pitting corrosion depth of steel structures in marine environment using Bayesian network (BN). The proposed BN model combines an understanding of corrosion phenomenological model and empirical model calibrated using real-world data. A case study, which exemplifies the application of methodology to predict the pit depth of structural steel in long-term marine environment, is presented. The result shows that the proposed methodology succeeds in predicting the time-dependent, long-term anaerobic pitting corrosion depth of structural steel in different environmental and operational conditions.

Computers for data, control and simulation

1988 ◽  
Vol 46 ◽  
pp. 920-921
Author(s):  
David C. Joy
Keyword(s):  
Personal Computers ◽  
Monitoring And Control ◽  
Data Logging ◽  
Data Logger ◽  
Operational Conditions ◽  
Data Control ◽  
The Many ◽  
And Control

Personal computers (PCs) are a powerful resource in the EM Laboratory, both as a means of automating the monitoring and control of microscopes, and as a tool for quantifying the interpretation of data. Not only is a PC more versatile than a piece of dedicated data logging equipment, but it is also substantially cheaper. In this tutorial the practical principles of using a PC for these types of activities will be discussed.The PC can form the basis of a system to measure, display, record and store the many parameters which characterize the operational conditions of the EM. In this mode it is operating as a data logger. The necessary first step is to find a suitable source from which to measure each of the items of interest. It is usually possible to do this without having to make permanent corrections or modifications to the EM.

Increase of resistance of piercing mill mandrels at seamless pipes production of 13Cr grade martensite class stainless steel at line ТПА 159‒426 of JSC VTZ

2020 ◽  
Vol 76 (12) ◽  
pp. 1259-1264
Author(s):  
I. I. Lube ◽  
N. V. Trutnev ◽  
S. V. Tumashev ◽  
A. V. Krasikov ◽  
A. G. Ul’yanov ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Oil And Gas ◽  
Cobalt Content ◽  
Pipe Plant ◽  
Piercing Mill ◽  
Steel Strength ◽  
New Material ◽  
Chemical Composition Of Steel ◽  
Technical Solutions ◽  
Grade Steel

At production of pipes of type 13Cr grade steel used at development of oil and gas deposits in areas with aggressive environment, intensive wear of instrument takes place, first of all, piercing mill mandrels. Factors, influencing the resistivity of the piercing mandrels considered, including chemical composition of the material, the mandrel is made of and its design. Based on industrial experience it was shown, that chrome content in the mandrel material practically does not affect on the increase of its resistivity, since the formed thin protective oxides having high melting temperature, are quickly failed and practically are not restored in the process of piercing. To increase the resistivity of piercing mandrels at production of casing tubes of type 13Cr grade steel, a work was accomplished to select a new material for their manufacturing. The chemical composition of steel presented, which was traditionally used for piercing mandrels manufacturing, as well as a steel grade proposed to increase their resistivity. First, molybdenum content was increased, which increases the characteristics of steel strength and ductility at high temperatures and results in grain refining. Second, tungsten content was also increased, which forms carbides in the steel resulting in an increase of its hardness and “red resistivity”, as well as in preventing grains growth during heating. Third, cobalt content was also increased, which increases heat resistivity and shock loads resistivity. The three elements increase enabled to increase the mandrels resistivity by two times. Results of mandrel test of steel 20ХН2МВ3КБ presented, the mandrel having corrugation on the working cone surface, which enabled to reach the resistivity growth to 12 passes without significant change of instrument cost. Microstructure of mandrels made of steels 20Х2Н4МФА and 20ХН2МВ3КБ shown. Application of the centering pin of special design was tested, which provided forming of a rounding edge on the front billet ends, eliminated undercut of mandrel external surface in the process of secondary billet grip and increase the service life of the piercing mill mandrels. At production of seamless pipes of martensite class type 13Cr stainless steels having L80 group of strength, an increase of piercing mandrel resistivity was reached by more than four times, which together with other technical solutions enabled to increase the hourly productivity of the hot rolling section of Volzhsky pipe plant ТПА 159-426 line by more than two times.

Spatial assemblage structure of shallow-water reef fish in Southwest Australia

2020 ◽  
Vol 649 ◽  
pp. 125-140
Author(s):  
DS Goldsworthy ◽  
BJ Saunders ◽  
JRC Parker ◽  
ES Harvey
Keyword(s):  
Shallow Water ◽  
Reef Fish ◽  
Marine Environment ◽  
Fish Assemblages ◽  
Canopy Cover ◽  
Reef Fishes ◽  
Reef Fish Assemblage ◽  
Reef Type ◽  
Present Distribution ◽  
Southwest Australia

Bioregional categorisation of the Australian marine environment is essential to conserve and manage entire ecosystems, including the biota and associated habitats. It is important that these regions are optimally positioned to effectively plan for the protection of distinct assemblages. Recent climatic variation and changes to the marine environment in Southwest Australia (SWA) have resulted in shifts in species ranges and changes to the composition of marine assemblages. The goal of this study was to determine if the current bioregionalisation of SWA accurately represents the present distribution of shallow-water reef fishes across 2000 km of its subtropical and temperate coastline. Data was collected in 2015 using diver-operated underwater stereo-video surveys from 7 regions between Port Gregory (north of Geraldton) to the east of Esperance. This study indicated that (1) the shallow-water reef fish of SWA formed 4 distinct assemblages along the coast: one Midwestern, one Central and 2 Southern Assemblages; (2) differences between these fish assemblages were primarily driven by sea surface temperature, Ecklonia radiata cover, non-E. radiata (canopy) cover, understorey algae cover, reef type and reef height; and (3) each of the 4 assemblages were characterised by a high number of short-range Australian and Western Australian endemic species. The findings from this study suggest that 4, rather than the existing 3 bioregions would more effectively capture the shallow-water reef fish assemblage patterns, with boundaries having shifted southwards likely associated with ocean warming.

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