Field Implementation of RBI for Jacket Structures

2005 ◽  
Vol 127 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Michael Havbro Faber ◽  
John D. Sørensen ◽  
Jesper Tychsen ◽  
Daniel Straub
Keyword(s):  
Sensitivity Analysis ◽  
Stress Ratio ◽  
Inspection Planning ◽  
Membrane Stress ◽  
Steel Jacket ◽  
The North ◽  
Large Numbers ◽  
Structural Details ◽  
Jacket Structures ◽  
The North Sea

After a brief outline of the simplified and generic approach to reliability- and risk-based inspection planning, focus is set on a recent application of the methodology for the planning of in-service NDT inspections of fixed offshore steel jacket structures in the Danish part of the North Sea. The study includes a sensitivity analysis performed for the identification of relevant generic parameters such as the bending to membrane stress ratio, the design fatigue life, and the material thickness. Based on the results of the sensitivity analysis, a significant number of inspection plans were computed for fixed generic parameters (predefined generic plans) and a database named iPlan was developed from which inspection plans may be obtained by interpolation between the predefined generic plans. The iPlan database facilitates the straightforward production of large numbers of inspection plans for structural details subject to fatigue deterioration, as illustrated by an example in the paper.

Field Implementation of RBI for Jacket Structures

2003 ◽  
Author(s):  
Michael H. Faber ◽  
Daniel Straub ◽  
John D. So̸rensen ◽  
Jesper Tychsen
Keyword(s):  
Sensitivity Analysis ◽  
Data Base ◽  
Stress Ratio ◽  
Oil And Gas ◽  
Inspection Planning ◽  
The North ◽  
Large Numbers ◽  
Structural Details ◽  
Jacket Structures ◽  
The North Sea

The present paper first gives a brief outline of the simplified and generic approach to reliability and risk based inspection planning and thereafter sets focus on a recent application of the methodology for planning of in-service NDT inspections of the fixed offshore steel jacket structures in the DUC concession area in the Danish part of the North-Sea. The platforms are operated by Maersk Oil and Gas on behalf of DUC partners A.P. Mo̸ller, Shell and Texaco. The study includes a sensitivity analysis performed for the identification of relevant generic parameters such as the bending to membrane stress ratio, the design fatigue life and the material thickness. Based on the results of the sensitivity analysis a significant number of inspection plans were computed for fixed generic parameters (pre-defined generic plans) and a data-base named iPlan was developed from which inspection plans may be obtained by interpolation between the pre-defined generic plans. The iPlan data-base facilitates the straightforward production of large numbers of inspection plans for structural details subject to fatigue deterioration. In the paper the application of the generic inspection plan database iPlan is finally illustrated on an example.

20 YEARS DECOMMISSIONING EXPERIENCE - EVOLUTION OF INNOVATIVE SOLUTIONS

2021 ◽  
Vol 157 (A4) ◽  
Author(s):  
V McCarthy ◽  
P Lai ◽  
P Smith
Keyword(s):  
North Sea ◽  
Market Sector ◽  
The North ◽  
Innovative Solutions ◽  
Jacket Structures ◽  
The North Sea ◽  
Subsea Pipelines ◽  
Innovative Techniques

Decommissioning is an increasing market sector which has been gradually gathering momentum particularly in the North Sea. The forecast expenditure for removing existing platforms increases with time. This comes together with the increasing complexity of the decommissioning operation. Experience and expertise in this field are key for success. Saipem have been contracted to perform a number of ‘removals’ ranging from subsea templates, subsea pipelines, seabed debris clearance, jacket structures and topside modules. This paper provides an account of our experience gained over the last 20 years performing decommissioning activities. The paper presents the evolution of the techniques developed and focuses in particular on the Lift and Tow method developed after 2004 for a number of subsea applications. Problems always materialise post contract award due to inadequate data. The paper gives a detailed description of the Lift and Tow method along with various innovative techniques developed for this method, ranging from lifting operations supported by motion forecasting through to personnel access onto the structures.

Underwater Wet Repair Welding and Strength Testing on Pipe-Patch Joints

1998 ◽  
Vol 120 (4) ◽  
pp. 237-242 ◽  
Author(s):  
R. Wernicke ◽  
R. Pohl
Keyword(s):  
Hot Spot ◽  
Fatigue Behavior ◽  
High Hydrogen ◽  
Underwater Wet Welding ◽  
The North ◽  
Repair Patch ◽  
Structural Details ◽  
The North Sea ◽  
Welded Pipe ◽  
Sea Area

The underwater wet welding method for repairing of submerged structural members has been intensively developed during the last years. It is an economical and especially more time-independent procedure. The shortened repair duration is a major advantage in regions with rough sea climate as the North Sea area. During research projects the weldability and fatigue performance of pipe-patch connections have been tested. These joints are in use for repairing of collision indents. The shape of the actual used repair patch was optimized to the requirements of underwater wet welding at high tensile strength steels as BS4360 Gr 50D. Steel materials in this grade show problems in regard to high hydrogen susceptibility, and therefore cold cracking. The fatigue behavior of the patch-welded pipe structural member has been investigated. First test series were carried out using as-welded joints. In a second part of the project, post-weld-treated connections were tested. The weld seams on these joints were partially ground or hammer peened. The test results have been evaluated by means of the hot-spot concept and then faced with actual code requirements. Extensive strain gage measurements and finite-element calculations have been carried out to provide the stress state in the structural details.

Toward Effective International Cooperation on Climate Change: Numbers, Interests and Institutions

2006 ◽  
Vol 6 (3) ◽  
pp. 90-103 ◽  
Author(s):  
David G. Victor
Keyword(s):  
Climate Change ◽  
Kyoto Protocol ◽  
International System ◽  
Climate Agreements ◽  
The North ◽  
Large Numbers ◽  
The North Sea ◽  
Ambitious Program ◽  
High Level ◽  
Effective Use

Arild Underdal's “law of the least ambitious program” is properly pessimistic about the prospects for cooperation in the international system where nations must give their consent to be bound by meaningful commitments. Those pessimistic expectations are now being revealed in the collective efforts to address the problem of climate change, notably through the Kyoto Protocol. Over-coming Underdal's law requires narrowing the numbers of countries that participate in key climate agreements and tailoring membership so that just the most important countries are engaged and there are strong incentives to avoid defection. At the same time, the effectiveness of cooperative efforts would gain from fuller use of nonbinding instruments, review procedures and high level conferences—as were put to effective use in the North Sea cooperation, for example— in addition to legally binding international law through instruments such as the Kyoto Protocol. Sadly, most of the conventional wisdom runs the opposite direction, favoring binding treaties among large numbers of countries.

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