Investigation of the Structural Strength of Existing Blast Walls in Well-Test Areas on Drillships

Blast walls are installed on the topside of offshore structures to reduce the damage from fire and explosion accidents. The blast walls on production platforms such as floating production storage, offloading, and floating production units undergo fire and explosion risk analysis, but information about blast walls on the well-test area of drillship topsides is insufficient even though well tests are performed 30 to 45 times per year. Moreover, current industrial practices of design method are used as simplified elastically design approaches. Therefore, this study investigates the strength characteristic of blast wall on drillship based on the blast load profile from fire and explosion risk analysis results, as well as the ability of the current design scantling of the blast wall to endure the blast pressure during the well test. The maximum plastic strain of the FE results occurs at the bottom connection between the vertical girder and the blast wall plate. Based on the results, several alternative design applications are suggested to reduce the fabrication cost of a blast wall such as differences of stiffened plated structure and corrugated panels, possibility of changing material (mild steel), and reduced plate thickness for application in current industrial practices.

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Explosion Risk Analysis on the Liquefaction Process of LNG-FPSO at the PFD Level

Volume 3B: Structures, Safety and Reliability ◽

10.1115/omae2017-62163 ◽

2017 ◽

Author(s):

Wonwo You ◽

Jaeuk Park ◽

Youngsub Lim

Keyword(s):

Risk Analysis ◽

Oil And Gas ◽

Risk Estimation ◽

Ignition Probability ◽

Specific Process ◽

Frequency Calculation ◽

Fire And Explosion ◽

Liquefaction Process ◽

Explosion Accidents ◽

Explosion Risk

The potential risk of an offshore processing facility is the major important part in the oil and gas industry due to its limited space causing difficulties in evacuation. An offshore processing facility is normally exposed to flammable oil and gas in the operating phase. Especially, uncontrolled hydrocarbon leaks or ruptures of the equipment present main threats. These failures can lead to fire and explosion disaster. Some studies have proposed fire and explosion assessment methodologies and made fire and explosion assessment tools. These tools can provide risk assessments result using physical effect modelling software and following the related standards or engineering practices according to accident scenarios. Nevertheless, existing fire and explosion assessment procedures are still not comprehensive enough to applicate a specific process due to its complexity and are not clear which stage in a project is appropriate for applying it. This paper focuses only on explosion accidents and discusses the development of an explosion risk analysis procedure possible to apply at process flow diagram (PFD) level. The explosion risk analysis procedure using PFD has 6 steps; modelling of a process, scenario selection, inventory calculation, frequency calculation, consequence modelling and risk estimation. It starts at modelling of a specific process using process simulation software, HYSYS. The process modelling can be optimized by the existing methods and finally provide the PFD for the specific process. In the scenario selection step, the information required to perform a risk analysis is identified. The inventory calculation conducts to calculate the inventory of a defined segment after sizing of the equipment in the PFD. The frequency calculation consists of leak frequency and ignition probability. The leak frequency can be calculated with historical database and the ignition probability can be calculated with a specific ignition probability model. The consequence modelling is conducted by using physical effect modelling software, PHAST. It can provide the distance to specified overpressure. Finally, at the risk estimation step, the risk results are evaluated. This procedure can help to applicate a specific process easily and provide explosion risk assessment tool at PFD level. This paper conducts the case study for a liquefied natural gas floating production storage offloading (LNG-FPSO) which is one of the representative offshore processing facilities. Especially, a natural liquefaction process in a LNG-FPSO, which liquefies the processed natural gas to store in a storage tank of a LNG-FPSO, is the most important process in terms of cost and risk. In the situation the most of ongoing or prospective projects for LNG-FPSO adopt dual mixed refrigerants (DMR) liquefaction process, the representative configurations of the DMR liquefaction processes are evaluated and compared. It can help decision making through providing which configuration has an advantage in terms of explosion accidents.

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Fire and Explosion Risk Analysis of Oxidation Process Based on FFTA-LOPA Method

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/392/4/042002 ◽

2018 ◽

Vol 392 ◽

pp. 042002

Author(s):

M N Wei ◽

L J Zhang ◽

G Tao

Keyword(s):

Risk Analysis ◽

Oxidation Process ◽

Fire And Explosion ◽

Explosion Risk

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Quantitative Risk Analysis of Offshore Fire and Explosion Based on the Analysis of Human and Organizational Factors

Mathematical Problems in Engineering ◽

10.1155/2015/537362 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Yan Fu Wang ◽

Yu Lian Li ◽

Biao Zhang ◽

Pei Na Yan ◽

Li Zhang

Keyword(s):

Risk Analysis ◽

Organizational Factors ◽

Event Tree ◽

Analysis Framework ◽

Analysis Model ◽

Quantitative Risk Analysis ◽

Dynamic Risk ◽

Fire And Explosion ◽

Human And Organizational Factors ◽

Explosion Risk

A dynamic risk analysis model of offshore fire and explosion is proposed in this paper. It considers the effect of human and organizational factors in a more explicit way than current traditional risk analysis methods. This paper begins with exploring the recent advances on offshore fire and explosion risk analysis theories, followed by briefly introducing the research techniques employed in the proposed hybrid causal logic model which consists of event tree, fault tree, Bayesian network, and system dynamics. Thereafter, it proposes a quantitative risk analysis framework. At last, the applicability of this model to the offshore platform is also discussed. It aims to provide guideline for risk analysis of offshore fire and explosion.

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Research on Structural Strength of Catamaran Superstructure Constructed with Aluminum Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.538-541.3165 ◽

2012 ◽

Vol 538-541 ◽

pp. 3165-3169

Author(s):

Yuan Zhou Zheng ◽

Yan Ling Huang ◽

Kai Zhou Peng

Keyword(s):

Aluminum Alloy ◽

Structural Strength ◽

Design Method ◽

Plate Thickness ◽

Side Wall ◽

Front Wall ◽

Strength Theory ◽

Local Strength ◽

Standard Design ◽

The Relationship

The design of Superstructure constructed with aluminum alloy do not have to follow the traditional standard design method. It can be designed by applying strength theory and ANSYS program or MSC Patran / Nastran program, which can ensure the strength requirements with the selected aluminum alloy components and make the weight of the ship lightest. In this paper, the 42.4m catamaran sightseeing boat is used as an example. The structural strength of the superstructure constructed with aluminum alloy is calculated by MSC Patran / Nastran program. The distribution of the superstructure stress is obtained, which proved the size of the selected components of the superstructure can meet the requirements of the local strength and can be the reference of selecting the structure size. As the other conditions are unchanged, the the local thickness of the junction of the front wall and the side wall of the compass deck is changed. the relationship between plate thickness and stress is obtained. It is found that as The plate thickness is thicker, the stress there decreases; and as the thickness is smaller, it is obvious to reduce stress as the plate thickness Increase. when the thickness increases to a certain extent, the effect of the plate stress decreases is not obvious.

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Monotonic Response of Exposed Base Plates of Columns: Numerical Study and a New Design Method

Metals ◽

10.3390/met10030396 ◽

2020 ◽

Vol 10 (3) ◽

pp. 396

Author(s):

Héctor Díaz ◽

Eduardo Nuñez ◽

Claudio Oyarzo-Vera

Keyword(s):

Numerical Study ◽

Design Method ◽

Numerical Models ◽

Failure Mechanisms ◽

Plate Thickness ◽

Base Plate ◽

Traditional Design ◽

Current Design ◽

Bending Loads ◽

Base Plates

This paper describes a numerical study of the behavior of exposed base plates of columns under the action of axial and bending loads. The aim of this research is to evaluate numerically the failure mechanisms on stiffened and non-stiffened base plates and propose a new design method. The effects of base plate thickness, location of anchor rods, location of stiffeners and tensile strength of anchor rods were considered in the analysis. Sixteen finite elements simulations were performed considering different combinations of the above mentioned parameters. The results show a fragile response in the base plates when high resistance anchor rods are used. The anchor rods worked as fuse elements in base plates with a large thickness or many stiffeners. Additionally, the models with anchor bars located outside of the column flanges showed lower flexural strength and rotational stiffness compared to the models with anchor rods located between column flanges. The simulations showed that the base plate strength was determined by the simultaneous failure mechanisms of two or more components, different to what is stated in current design guides. Finally, the new method is suitable to design base plates with stiffened and not stiffened configurations, which unlike traditional design methods, show a good adjustment with numerical models.

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