SYMPOSIUM. FIXED OFFSHORE STRUCTURES: THE NEW CODE OF PRACTICE BS6235. ICE, LONDON 15 NOVEMBER 1982. SITE INVESTIGATIONS; DESIGN OF FOUNDATI -ONS; INSPECTION AND MAINTENANCE.

1983 ◽  
Vol 74 (3) ◽  
pp. 571-583
Author(s):  
FS WEST ◽  
JN MCFEETERS ◽  
A GALLAGHER ◽  
P GEORGE ◽  
WJ RIGDEN ◽  
...  
Keyword(s):  
Offshore Structures ◽  
Code Of Practice ◽  
Site Investigations ◽  
Inspection And Maintenance

scholarly journals Maintenance Planning of Offshore Wind Turbine Using Condition Monitoring Information

2009 ◽  
Author(s):  
Jose´ G. Rangel-Rami´rez ◽  
John D. So̸rensen
Keyword(s):  
Condition Monitoring ◽  
Wind Turbines ◽  
Wind Farm ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Maintenance Planning ◽  
Offshore Wind Turbines ◽  
Inspection And Maintenance ◽  
Monitoring Information

Deterioration processes such as fatigue and corrosion are typically affecting offshore structures. To “control” this deterioration, inspection and maintenance activities are developed. Probabilistic methodologies represent an important tool to identify the suitable strategy to inspect and control the deterioration in structures such as offshore wind turbines (OWT). Besides these methods, the integration of condition monitoring information (CMI) can optimize the mitigation activities as an updating tool. In this paper, a framework for risk-based inspection and maintenance planning (RBI) is applied for OWT incorporating CMI, addressing this analysis to fatigue prone details in welded steel joints at jacket or tripod steel support structures for offshore wind turbines. The increase of turbulence in wind farms is taken into account by using a code-based turbulence model. Further, additional modes t integrate CMI in the RBI approach for optimal planning of inspection and maintenance. As part of the results, the life cycle reliabilities and inspection times are calculated, showing that earlier inspections are needed at in-wind farm sites. This is expected due to the wake turbulence increasing the wind load. With the integration of CMI by means Bayesian inference, a slightly change of first inspection times are coming up, influenced by the reduction of the uncertainty and harsher or milder external agents.

scholarly journals ON STANDARDIZATION OF LABORATORY SOIL TESTING IN OFFSHORE GEOTECHNICAL SURVEY

Gruntovedenie ◽  
2021 ◽  
Vol 1 (16) ◽  
pp. 16-52
Author(s):  
E.A. Voznesensky ◽  
◽  
A.S. Loktev ◽  
M.S. Nikitin ◽  
◽  
...  
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Offshore Structures ◽  
Soil Testing ◽  
National Standard ◽  
Gas Industry ◽  
Code Of Practice ◽  
Complete Section ◽  
Testing Practice ◽  
Russian Soil

Issues of laboratory soil studies standardization in offshore geotechnical survey are discussed in connection with the end of expertise of two new regulative documents – new edition of the Code of practice and Russian national standard developed on the basis of international ISO standard. Since these documents of different level belong also to different categories (geotechnical survey and oil and gas industry), the authors analyze their interrelation and consistency, from one hand, and the preparedness of Russian soil testing practice to implementation of the new standard which results from harmonization with international ones, from the other. Complete section of the standard draft related to soil laboratory testing is presented, preceded by commentary on some important issues regarding the implementation of its specific methodic statements. It is concluded that the new national GOST draft «Petroleum and natural gas industries. Specific requirements for offshore structures. Marine soil investigations» developed on ISO basis will be a useful document supported in general by Russian normative base but expanding a possible range of voluntary methods into well time-tested foreign approaches. This documents can be considered to be a toolkit annex to the Code of practice describing testing approaches beyond the scope of typical tasks

scholarly journals Planning and Design of Site Investigations

1986 ◽  
Vol 2 (1) ◽  
pp. 1-5 ◽  
Author(s):  
J. M. Head
Keyword(s):  
Preliminary Design ◽  
Formal Approach ◽  
Design Assessment ◽  
Code Of Practice ◽  
Site Investigations ◽  
Planning And Design ◽  
Ground Conditions

AbstractGuidance on planning and design of site investigations is not explicitly included in the Code of Practice for Site Investigations (1981). Insufficient emphasis is given to developing a strategy and a programme of activities which is relevant to the proposed development and ground conditions.A more formal approach to the organisation of these preliminary stages is presented and an outline given for a planned programme of administration.Guidelines are given on how to develop an appropriate strategy including categorisation of investigation, preliminary design assessment and detailing site work. The need for records and refinement is highlighted.

scholarly journals Reliability Updating of Offshore Structures Subjected to Marine Growth

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 414
Author(s):  
Franck Schoefs ◽  
Thanh-Binh Tran
Keyword(s):  
Limit State ◽  
Dynamic Bayesian Network ◽  
Offshore Structures ◽  
Drag Forces ◽  
The North ◽  
The North Sea ◽  
Inspection And Maintenance ◽  
Inspection Data ◽  
Atlantic Area

Marine growth is a known problem for oceanic infrastructure and has been shown to negatively impact the reliability of bottom-fixed or floating offshore structures submitted to fatigue or extreme loading. Among other effects, it has been shown to change drag forces by increasing member diameters and modifying the roughness. Bio-colonization being highly random, the objective of this paper is to show how one-site inspection data increases reliability by decreasing uncertainties. This can be introduced in a reliability-based inspection framework for optimizing inspection and maintenance (here, cleaning). The modeling and computation are illustrated through the reliability analysis of a monopile in the European Atlantic area subjected to marine growth and according to the plastic collapse limit state. Based on surveys of structures in the North Sea, long-term stochastic modeling (space and time) of the marine growth thickness is first suggested. A Dynamic Bayesian Network is then developed for reliability updating from the inspection data. Finally, several realistic (10–20 measurements) inspection strategies are compared in terms of reliability improvement and the accuracy of reliability assessment.

Underwater inspection of offshore structures

1978 ◽  
Vol 76 (1-3) ◽  
pp. 181-191
Author(s):  
P. H. Milne
Keyword(s):  
Research Team ◽  
Offshore Structures ◽  
Reference Points ◽  
Navigation Systems ◽  
Complete Structure ◽  
Underwater Acoustic ◽  
Radio Stations ◽  
Offshore Installations ◽  
Inspection And Maintenance ◽  
The University

SynopsisUnder the Offshore Installations (Construction and Survey) Regulations 1974 all structures established or maintained in UK waters must possess a valid certificate of fitness. To obtain this certificate annual visual inspections of parts of the structure must be carried out both above and below water. A major survey of the complete structure or platform is required every five years.Underwater inspections may be carried out down to 50 m by divers on surface demand. Below 50 m when divers are involved it is essential to use either a diving bell or lock-out submersible. To avoid saturation diving and reduce diving hazards, the unmanned submersible has been developed as an underwater inspection tool.Various navigation systems have been developed for offshore position fixing. Deepwater navigation and surveying relies on a combination of surface radio stations and seabed underwater acoustic transponders. Platform navigation for underwater inspection and maintenance is a major problem due to poor diving access and few underwater reference points.The inefficiency of the present diver operated navigation and survey systems round platforms is now being investigated by a research team from the University of Strathclyde. Preliminary tests of equipment have already been carried out in a diving tank and at sea.

SYMPOSIUM. FIXED OFFSHORE STRUCTURES: THE NEW CODE OF PRACTICE BS6235. ICE, LONDON, 15 NOVEMBER 1982. FINAL SESSION.

1983 ◽  
Vol 74 (3) ◽  
pp. 581-583
Author(s):  
RJ PANNETT ◽  
DG SPICKERNELL ◽  
P STUART ◽  
J HARRISON ◽  
RK VENABLES ◽  
...  
Keyword(s):  
Offshore Structures ◽  
Final Session ◽  
Code Of Practice

Fuzzy Reliability Assessment for Offshore Structures Considering Inspection and Maintenance

2003 ◽  
Author(s):  
Liangbin Xu ◽  
Guoming Chen
Keyword(s):  
Structural Reliability ◽  
Flaw Detection ◽  
Reliability Assessment ◽  
Offshore Structures ◽  
Distribution Parameter ◽  
Fuzzy Synthetic Evaluation ◽  
Bayesian Theorem ◽  
Prior Probabilities ◽  
Inspection And Maintenance ◽  
Non Destructive

It has been shown that probabilistic model is an effective tool in assessing structural reliability incorporating the information from non-destructive inspection (NDT) of offshore structures. However, the preceding theorems fail to adequately deal with the uncertainties of fuzzy character that are associated with NDT for offshore structures. This paper is aimed at an initial investigation on reliability theory of structure involved with fuzziness considering inspection and maintenance. Based on the basic principles of fuzzy set theory, a fuzzy Bayesian procedure is proposed to quantify the fuzzy uncertainty, including the NDT uncertainty in the flaw size determination and the flaw detection, the modeling uncertainty in model selection and the uncertainty in distribution parameter. This paper presents an algorithm to compute the posterior probability of model weights and the posterior distribution of distribution parameter employing the fuzzy Bayesian theorem. The prior probabilities of model weights may be determined based on fuzzy synthetic evaluation. A method for reliability assessment upon inspection and maintenance considering fuzzy uncertainties is put forward in this paper. The example is investigated to illustrate the validation of the proposed method. It is found that the effect of fuzzy uncertainties could be very significant in assessing structural reliability.

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