ISUM for Offshore Frame Structures

2016 ◽  
Author(s):  
J. Amdahl ◽  
T. Holmas
Keyword(s):  
Computer Program ◽  
Oil And Gas ◽  
Frame Structures ◽  
Limit States ◽  
Environmental Loads ◽  
Offshore Industry

The paper presents the background and major ideas behind the computer program USFOS. The program is today widely used by the offshore industry to assess the resistance of oil and gas installations against abnormal environmental loads and accidental actions, such as ship collisions, fires and explosions. The assessment is normally performed in the accidental limit states; i.e. substantial yielding, buckling, partial collapse may take place, but the structure should maintain overall integrity. The features and concepts and models adopted in USFOS have also proved to be very useful in the analysis of totally different edifices. A few examples of this are given in the paper.

Identifying Key Safety Culture Factors for the Offshore Industry

2021 ◽  
Author(s):  
Ning Lou ◽  
Ezra Wari ◽  
James Curry ◽  
Kevin McSweeney ◽  
Rick Curtis ◽  
...  
Keyword(s):  
Safety Culture ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Transportation Safety ◽  
Key Factors ◽  
Gas Industry ◽  
The Us ◽  
Offshore Industry ◽  
Offshore Oil And Gas ◽  
Offshore Oil

This research identifies key factors, or safety culture categories, that can be used to help describe the safety culture for the offshore oil and gas industry and develop a comprehensive offshore safety culture assessment toolkit for use by the US Gulf of Mexico (GoM) owners and operators. Detailed questionnaires from selected safety culture frameworks of different industries were collected and analyzed to identify important safety culture factors and key questions for assessment. Safety frameworks from different associations were investigated, including the Center for Offshore Safety (COS), Bureau of Safety and Environmental Enforcement (BSEE), and the National Transportation Safety Board (NTSB). The safety culture factors of each of these frameworks were generalized and analyzed. The frequency of the safety culture factors in each framework was analyzed to explore commonality. The literature review and analysis identified a list of common factors among safety culture frameworks.

scholarly journals Integrity Management of Marine Structures; With Emphasis on Design for Structural Robustness

2018 ◽  
Author(s):  
Torgeir Moan
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Offshore Structures ◽  
Design Standards ◽  
Limit States ◽  
Fabrication Errors ◽  
Integrity Management ◽  
Operational Errors ◽  
And Control

Based on relevant accident experiences with oil and gas platforms, a brief overview of structural integrity management of offshore structures is given; including an account of adequate design criteria, inspection, repair and maintenance as well as quality assurance and control of the engineering processes. The focus is on developing research based design standards for Accidental Collapse Limit States to ensure robustness or damage tolerance in view damage caused by accidental loads due to operational errors and to some extent abnormal structural damage due to fabrication errors. Moreover, it is suggested to provide robustness in cases where the structural performance is sensitive to uncertain parameters. The use of risk assessment to aid decisions in lieu of uncertainties affecting the performance of novel and existing offshore structures, is briefly addressed.

An Innovative Synthetic Mooring Solution for an Octagonal FPSO in Shallow Waters

2010 ◽  
Author(s):  
Mo Fan ◽  
Da Li ◽  
Tuanjie Liu ◽  
Alex Ran ◽  
Wei Ye
Keyword(s):  
Oil And Gas ◽  
Shallow Waters ◽  
Manufacturing Processes ◽  
Mooring System ◽  
Oil And Gas Development ◽  
Mooring Lines ◽  
Environmental Loads ◽  
Design And Manufacturing ◽  
Full Production ◽  
Three Bundles

An octagonal FPSO has been proposed for marginal oil and gas development in shallow waters. A shuttle tanker will be deployed near the FPSO during offloading operations. This new concept simplifies the design and manufacturing processes, yet maintains full production, storage, and offloading functions of a conventional ship-shaped FPSO. However, design of the mooring system for this floating unit imposes technical challenges due to: 1) high environmental loads expected on this unit, 2) large dynamic offsets of the unit in shallow waters, and 3) inadequate performance of catenary mooring systems in shallow waters. Thus, development of a viable station keeping solution becomes a key issue to the new concept FPSO design. In this paper, an innovative mooring system is designed to meet the challenges. The FPSO mooring system consists of pile anchors, bridle chains, anchorage buoys, and polyester ropes. Nine mooring lines are grouped into three bundles which evenly spread around the FPSO. The shuttle tanker is attached to the FPSO with a nylon rope hawser at the bow and secured to pre-installed anchorage buoys at the stern with two other nylon ropes. Analyses have been performed for the FPSO mooring system. It is concluded that the proposed mooring system is fully functional and effective.

Evaluation of Methods to Predict Safe Welding Conditions and Maximum HAZ Hardness in Steel Welding

1995 ◽  
Vol 117 (1) ◽  
pp. 46-56 ◽  
Author(s):  
J. P. Tronskar
Keyword(s):  
Oil And Gas ◽  
High Strength Steels ◽  
Offshore Structures ◽  
Structural Steels ◽  
Gas Production ◽  
Carbon Equivalent ◽  
Chemical Compositions ◽  
International Institute ◽  
Empirical Formulas ◽  
Offshore Industry

During the last ten years new structural steels of improved weldability have been introduced. In particular, structural steels for the fabrication of offshore structures have been greatly improved in this respect throughout this period. These steels have lean chemical compositions which are generally outside the range for which the existing HAZ hardness criteria and the International Institute of Welding carbon equivalent (CEIIW) formula were originally developed. This paper presents the results from investigations of the weldability of three normalised (Re min 350 MPa) and three quenched and tempered (Re min 500 MPa) offshore structural steels. Weldability testing was conducted to study the relative performance of the different steels and to obtain a comparison between the capability of the different methods to predict safe welding conditions to avoid cold cracking in steel welding. It has become a widespread practice in welding high-strength steels to incorporate maximum HAZ hardness restrictions in fabrication specifications, particularly so in the offshore industry. Maximum HAZ hardness restrictions are often a point of contention between fabricators and their clients due to the difficulties often experienced in meeting these hardness requirements. Problems meeting maximum HAZ hardness requirements have been encountered for applications where maximum hardness HRC 22 or Vickers HV10 260 have been imposed for materials exposed to sour service in oil and gas production, processing and transportation. Many attempts have been made to develop empirical formulas for the estimation of maximum HAZ hardnesses. This paper presents some of the more successful approaches proposed to date and compares their performance.

Fatigue Analysis of Free Spanning Pipelines Subjected to Vortex Induced Vibrations

2013 ◽  
Author(s):  
F. Van den Abeele ◽  
F. Boël ◽  
M. Hill
Keyword(s):  
Fatigue Damage ◽  
Oil And Gas ◽  
Flow Direction ◽  
Cross Flow ◽  
Fatigue Analysis ◽  
Sensitivity Analyses ◽  
Vortex Induced Vibration ◽  
Vortex Induced Vibrations ◽  
Offshore Industry ◽  
Girth Welds

Vortex induced vibration is a major cause of fatigue failure in submarine oil and gas pipelines and steel catenary risers. Even moderate currents can induce vortex shedding, alternately at the top and bottom of the pipeline, at a rate determined by the flow velocity. Each time a vortex sheds, a force is generated in both the in-line and cross-flow direction, causing an oscillatory multi-mode vibration. This vortex induced vibration can give rise to fatigue damage of submarine pipeline spans, especially in the vicinity of the girth welds. In this paper, an integrated numerical framework is presented to predict and identify free spans that may be vulnerable to fatigue damage caused by vortex induced vibrations (VIV). An elegant and efficient algorithm is introduced to simulate offshore pipeline installation on an uneven seabed. Once the laydown simulation has been completed, the free spans can be automatically detected. When the fatigue screening for both inline and cross-flow VIV indicates that a particular span may be prone to vortex induced vibrations, a detailed fatigue analysis is required. Amplitude response models are constructed to predict the maximum steady state VIV amplitudes for a given pipeline configuration (mechanical properties) and sea state (hydrodynamic parameters). The vibration amplitudes are translated into corresponding stress ranges, which then provide an input for the fatigue analysis. A case study from the offshore industry is presented, and sensitivity analyses are performed to study the influence of the seabed conditions, where special emphasis is devoted on the selection of pipe soil interaction parameters.

Integration between RCM and RAM: a case study

2016 ◽  
Vol 33 (6) ◽  
pp. 852-880 ◽  
Author(s):  
Ilaria De Sanctis ◽  
Claudia Paciarotti ◽  
Oreste Di Giovine
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Practical Method ◽  
Environmental Safety ◽  
Gas Industry ◽  
Content Type ◽  
Availability Analysis ◽  
Plant Safety ◽  
Offshore Industry

Purpose – The purpose of this paper is to propose a practical method of performing maintenance in the offshore industry where engineers have to manage problems such as the high cost of operations, assuring an high availability of the plant, safety on board and environmental protection. Indeed an efficient maintenance method it is necessary in order to offer methods and criteria to select the rights maintenance strategies keeping in to account the environmental, safety and production constrains. Design/methodology/approach – The paper provides an overview of reliability centered maintenance (RCM) and reliability, availability, maintainability methodologies and an integration of the two methodologies in a particular case study in the oil and gas sector. Findings – This paper suggests an improvement of the well-established RCM methodology applicable to industries with high priority level. It is proposed an integration between a reliability analysis and an availability analysis and an application on the offshore oil and gas industry. Practical implications – The methodology provides an excellent tool that can be utilized in industries, where safety, regulations and the availability of the plant play a fundamental role. Originality/value – The proposed methodology provides a practical method for selecting the best maintenance strategy considering the equipment redundancy and sparing, the asset’s performance over long time scales, and the system uptime, downtime and slowdowns.

FPSO and TLWP Interacting at a Reduced Distance for Dry Tree Completion System

2009 ◽  
Author(s):  
Edgard B. Malta ◽  
Fabiano P. Rampazzo ◽  
Roberto E. Cruz ◽  
Allan C. de Oliveira ◽  
Kazuo Nishimoto
Keyword(s):  
Oil And Gas ◽  
Mooring Line ◽  
Extreme Wave ◽  
Floating System ◽  
Innovative System ◽  
Physical Tests ◽  
Offshore Industry ◽  
Reducing Costs ◽  
Set Up ◽  
And Storage

Nowadays, an offshore industry challenge is developing a floating system with production, storage and offloading capabilities together with a dry tree system reducing costs and maintenance. A solution could be two offshore units working at the same area. The system consists of a unit with dry completion, like a well head platform with drilling and workover facilities, and other capable to produce the oil and gas, and storage them. A better option is to have both units coupled making them work as one. By doing this, it could be reduced the radius of the mooring line footprint and the risk of clashing between the lines and shuttle tankers. The dimensions of the unit with the dry tree could be decreased because some facilities could be allocated at the large unit with storage capacity. The main goal of this paper is show the viability of this innovative system composed by two offshore units. A Tension Leg Wellhead Platform (TLWP) and a Floating Production Storage and Offloading (FPSO) coupled by synthetic ropes and non-symmetrical mooring system. Some comparisons were done between the numerical results from Numerical Offshore Tank (TPN) and physical tests carried out in NMRI (National Maritime Research Institute - JAPAN). The model scale of 1:100 and the numerical model was set up with similar main properties and equivalent lines stiffness. The models were exposed to extreme wave conditions for some incidences. Besides that, regular wave and current analyses were generated as well.

On Determination of Acceptable Safety Class in Design of Pipe-In-Pipe (PIP) Systems

2014 ◽  
Author(s):  
Soheil Manouchehri ◽  
Guillaume Hardouin ◽  
David Kaye ◽  
Jason Potter
Keyword(s):  
Failure Modes ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Gas Production ◽  
Point Of View ◽  
Insulation Material ◽  
Limit States ◽  
Oil And Gas Production ◽  
Operational Conditions ◽  
Outer Pipe

Pipe-In-Pipe (PIP) systems are increasingly used in subsea oil and gas production where a low Overall Heat Transfer Coefficient (OHTC) is required. A PIP system is primarily composed of an insulated inner pipe which carries the production fluid and an outer pipe that protects the insulation material from the seawater environment. This provides a dry environment within the annulus and therefore allows the use of high quality dry insulation system. In addition, from a safety point of view, it provides additional structural integrity and a protective barrier which safeguards the pipeline from loss of containment to the environment. Genesis has designed a number of PIP systems in accordance with the recognized subsea pipeline design codes including DNV-OS-F101 [1]. In section 13 F100 of the 2013 revision, a short section has been included in which PIP systems are discussed and overall design requirements for such systems are provided. It has also been stated that the inner and outer pipes need to have the same Safety Class (SC) unless it can be documented otherwise. This paper looks at the selection of appropriate SC for the outer pipe in a design of PIP systems based on an assessment of different limit states, associated failure modes and consequences. Firstly, the fundamentals of selecting an acceptable SC for a PIP system are discussed. Then, different limit states and most probable failure modes that might occur under operational conditions are examined (in accordance with the requirements of [1]) and conclusions are presented and discussed. It is concluded that the SC of the outer pipe of a PIP system may be lower than that of the inner pipe, depending on the failure mode and approach adopted by the designer.

Influencing Competence in Structural Integrity Management

2002 ◽  
Author(s):  
C. J. Billington ◽  
S. A. Caruana
Keyword(s):  
Structural Integrity ◽  
Oil And Gas ◽  
Safety Management ◽  
Oil And Gas Exploration ◽  
Operational Life ◽  
Exploration And Production ◽  
Management Context ◽  
Integrity Management ◽  
Offshore Industry ◽  
And Control

The offshore industry has experienced significant changes in the regulation and control of oil and gas exploration and production. The move away from the prescriptive approach towards a goal-setting regime gives Duty Holders greater control and accountability over the safety management of operations. Whilst this approach encourages greater ownership of safety by Duty Holders and provides greater flexibility, it also places greater demands and responsibility for ongoing integrity management, particularly when operational life is extended beyond the original specification with the need to account for the ageing mechanisms. Therefore it is increasingly important to ensure that those responsible for integrity management have all the necessary competences for this task and that the Duty Holder provides the necessary system competence to support this activity. This paper examines the factors which influence competence throughout the life-cycle of Structural Integrity Management (SIM) activities, and provides a model that relates this to a systematic safety management context.

scholarly journals Failure Analysis of a Flare Tip Used in Offshore Production Platform in Qatar

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3426
Author(s):  
Elsadig Mahdi ◽  
Ali Esmaeili
Keyword(s):  
Chemical Analysis ◽  
Oil And Gas ◽  
Mechanical Characterization ◽  
Crack Nucleation ◽  
Harmful Effect ◽  
Optical Microscope ◽  
Careful Examination ◽  
Incoloy 800H ◽  
Production Platform ◽  
Offshore Industry

An immature failure of a gas flare tip used in Qatar oil and gas offshore industry was investigated throughout this study. The design lifetime of the flare was fifteen years; however, it manifested immature failure resulting in a reduction of its lifetime to ten years. The flare is composed of different parts where the upper flare body and wind deflector showed failure while other components were still healthy. The material used for the aforementioned failed parts was Incoloy 800H, which is a highly corrosion and high-temperature resistant steel alloy. The material was rolled up and welded together with different welding joints. The root cause of failure was identified by using chemical analysis and microstructural and mechanical characterizations. For the mechanical characterization, an optical microscope (OM) and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) analyses were used for the specimen extracted from the failed part in order to ensure that the material mentioned by the manufacturer demonstrated the same metallurgical properties. For the mechanical characterization, two sets of specimens were used, one close to the failure region and the other far from the failure area. The chemical analysis revealed that the material was truthfully Incoloy 800H. The mechanical examination results showed a significant reduction of mechanical properties, i.e., the ultimate tensile strength (UTS) and microhardness dropped by 44% and 41% for samples close and far from the failure regions, respectively. Careful examination of the failed parts indicated that failure mostly took place in the vicinity of the welds, in particular near the joints. Improper joint designs, as well as a number of joints being designed in tiny areas, worsened the harmful effect of the heat-affected zone (HAZ), resulting in crack nucleation in the HAZ regions. The effect of welding in a combination of harsh service conditions of flare caused further crack extension where they merged, resulting in final immature failure.

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