An assessment of uncertainties in fatigue analyses of steel jacket offshore platforms

1982 ◽  
Vol 4 (1) ◽  
pp. 9-16 ◽  
Author(s):  
James Kawamoto ◽  
S. Shyam Sunder ◽  
Jerome J. Connor
Keyword(s):  
Offshore Platforms ◽  
Steel Jacket

Technology of steel jackets load-out in deep-water offshore platforms from the barge

2020 ◽  
pp. 25-29
Author(s):  
F.G. Hasanov ◽  
Keyword(s):  
Deep Water ◽  
Great Majority ◽  
Problem Solution ◽  
Offshore Platforms ◽  
The Caspian Sea ◽  
Gas Field ◽  
Steel Jacket ◽  
Gravity Centre ◽  
Scientific Technical ◽  
Oil Gas

Currently, great attention is paid to the development issue of the shelf’s fuel and energy resources foremost in the oil-gas fields of the Caspian Sea. The problem solution requires the studying of great majority of scientific-technical issues. One of the significant problems is the lead-out of steel jacket from the offshore platform as a major element of oil-gas field hydro-technical facilities meant for the operation in the deep water. The calculations for the execution of operations with steel jacket of deep stationary platform from the block with the detailed chara- cteristics by the mass and gravity center coordinates alongside line data have been carried out with “SACS” and “STAAD.PRO” software programs. The steel jacket is pushed astern with the push-pull equipment on the barge. Due to the shift of gravity centre the jacket changes the trim in the stern. Through the elevation of trim angle brought in alignment with the friction ration between the jacket and barge, the jacket slides further itself. Herewith, the trim increases until the gravity centre of steel jacket on the barge is not in alignment with rotation centre of the large rocker arms. The studies helped to fix the position of the jacket’s gravity centre from the aft perpendicular, the trim moment, the trim of the barge, the draft with the bow and stern and the trim angle as well.

Development of a Methodology for Safety Assessment of Existing Steel Jacket Offshore Platforms

1990 ◽  
Author(s):  
R.K. Aggarwal ◽  
R.G. Bea ◽  
B.C. Gerwick ◽  
C.W. Ibbs ◽  
R.B. Reimer ◽  
...  
Keyword(s):  
Safety Assessment ◽  
Offshore Platforms ◽  
Steel Jacket

Performance of Steel Jacket Platforms in Recent Gulf of Mexico Hurricanes

2007 ◽  
Author(s):  
Frank J. Puskar ◽  
Sean M. Verret ◽  
Aditya Hariharan
Keyword(s):  
Gulf Of Mexico ◽  
American Petroleum Institute ◽  
Offshore Platforms ◽  
Management Service ◽  
Hurricane Andrew ◽  
Design Procedures ◽  
The Past ◽  
Steel Jacket ◽  
Water Damage

In the past few years there have been several large hurricanes in the Gulf of Mexico that have destroyed or damaged over 200 fixed offshore platforms. These include hurricanes lvan (2004), Katrina (2005) and Rita (2005). Prior to these, the most recent hurricane to cause this level of damage was hurricane Andrew in 1992. Below water damage consisted of separated underwater braces, buckled braces, broken legs, and cracked connections. Above water damage consisted of wind and wave damage to decks and topsides equipment. Interestingly there has been little if any pile damage in any of these hurricanes. Although some newer platforms suffered damage and even destruction, most of the destroyed and damaged platforms were of older vintage and designed to American Petroleum Institute (API) Recommended Practice 2A-WSD (RP2A) practices that have since been improved. This paper summarizes the types of damage and destruction that has been found, including likely causes. It describes how some of this damage correlates to API design procedures. The work is based upon a series of projects funded by the Minerals Management Service (MMS) to study the effects of hurricanes on these types of offshore facilities.

Sensitivity analyses for steel jacket offshore platforms

1981 ◽  
Vol 3 (1) ◽  
pp. 13-26 ◽  
Author(s):  
S. Shyam Sunder ◽  
J.J. Connor
Keyword(s):  
Sensitivity Analyses ◽  
Offshore Platforms ◽  
Steel Jacket

A non-destructive crack detection method for steel jacket offshore platforms based on global and local responses

2002 ◽  
Vol 29 (1) ◽  
pp. 85-97
Author(s):  
Md. Rabiul Alam ◽  
A SJ Swamidas
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Crack Detection ◽  
Detection Method ◽  
Offshore Platforms ◽  
Local Responses ◽  
Gaussian Integration ◽  
Finite Element Software ◽  
Steel Jacket ◽  
Global And Local

A crack detection method for steel jacket offshore platforms based on global (displacement) and local (strain) responses is presented in this paper. One side panel of an idealized three-dimensional space frame structure was used in the numerical analysis; substructuring technique in finite element method was utilized as the numerical analysis procedure. Isoparametric thin shell elements, with reduced Gaussian integration, were used to discretize the whole structure. ABAQUS finite element software was used to solve the problem and process all information relating to the above-mentioned global and local responses. Numerical results obtained in the analysis have been compared with those obtained using other types of elements available in ABAQUS. The global and local parameters (displacements and strains) have been normalized using those obtained from the uncracked structure. It has been observed that the largest changes (in strain and stress) occur around the crack, but significant changes occur even away from the cracking weld toe. For cracks occurring at "one or both" saddle point(s), significant differences in strain exist to identify whether the cracking is on one side or on both sides. Significant change in slope of normalized global displacements, obtained around the crack, indicates the location of crack.Key words: crack detection, global and local responses, substructuring.

Tuned Mass Damper for Vibration Control in Steel Jacket Platforms

2008 ◽  
Author(s):  
A. A. Golafshani ◽  
A. Gholizad
Keyword(s):  
Vibration Control ◽  
Fatigue Damage ◽  
Safety Margin ◽  
Tuned Mass Damper ◽  
Offshore Platforms ◽  
Control Mechanisms ◽  
Sea State ◽  
Steel Jacket ◽  
Mass Damper ◽  
Environmental Events

Considering the stress cycles in joints and members due to wave induced forces on offshore platforms, fatigue analysis is therefore one of the most important analyses in offshore platforms design. Most of steel jacket type platforms located in areas with relatively high ratios of operational sea-states to maximum design environmental events; fall in acceptable safety margin in inplace and seismic analyses. But in fatigue analyses they will face critical condition. Therefore it seems that utilizing control mechanisms with the aim of increasing fatigue life in such platforms will be more preferable to merely deck displacement control. Investigation of tuned mass dampers adjustable parameters optimality for vibration control of wave excited structures implies that optimum tuning and damping ratios are strongly dependent to sea-state in addition to system parameters. The efficiency of optimally designed tuned mass damper for fatigue damage mitigation in realistic steel jacket platforms has been evaluated in this study. Full stochastic spectral analysis method has been employed to estimate the maximum fatigue damage as objective function to be minimized. This leads to a min-max problem which has been solved with Micro Genetic Algorithm. Furthermore the efficiency of a variable TMD with different optimum mass for each sea-state has been evaluated in comparison with a TMD with constant parameters.

A method of technical diagnostics for offshore structures

1994 ◽  
Vol 16 (2) ◽  
pp. 43-48
Author(s):  
Do Son
Keyword(s):  
Diagnostic Method ◽  
Joint Venture ◽  
Oil And Gas ◽  
Residual Life ◽  
Life Time ◽  
Offshore Structures ◽  
Technical Diagnostics ◽  
Offshore Platforms ◽  
South Vietnam ◽  
Local Destruction

This paper describes the results of measurements and analysis of the parameters, characterizing technical state of offshore platforms in Vietnam Sea. Based on decreasing in time material characteristics because of corrosion and local destruction assessment on residual life time of platforms is given and variants for its repair are recommended. The results allowed to confirm advantage of proposed technical diagnostic method in comparison with others and have been used for oil and gas platform of Joint Venture "Vietsovpetro" in South Vietnam.

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