Offshore Bolted Flange Joint With Tolerant Annular Sealing
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Solution Overview
Problem
Bolted flanges in offshore structures face challenges with corrosion and alignment difficulties, leading to high installation costs and weather downtime risks, particularly due to the complexity of achieving precise alignment for effective sealing against water ingress.
Innovation Solution
A bolted joint design incorporating a compressible elastomeric sealing element sandwiched between a peripheral skirt and collar, allowing for larger alignment tolerances and a fluid-tight seal, along with installation guides to facilitate proper alignment of flanges, reduces installation time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a long grouted skirt is used to cover the butt joint and seal against water ingress, then corrosion protection is improved, but fabrication cost and installation time increase significantly
Solution Approach 1:
The sealing solution is divided into two separate components: a skirt that provides corrosion protection and a separate sealing element that prevents water ingress. This segmentation allows each component to be optimized independently and installed separately, reducing overall installation time while maintaining both corrosion protection and sealing effectiveness.
Solution Approach 2:
The sealing function is extracted from the grouted skirt concept and implemented as a separate sealing element. This allows the sealing function to be achieved without requiring a long grouted skirt, thereby reducing fabrication costs and installation time while still providing adequate corrosion protection through the skirt alone.
2Reliability
If a long grouted skirt is used to seal against water ingress, then sealing integrity is improved, but fabrication cost increases
Solution Approach 1:
The sealing function is extracted from the grouted skirt and implemented as a separate sealing element. This allows the skirt to be a simpler, less expensive component while the sealing element provides the required sealing integrity at a lower overall cost than a long grouted skirt.
Solution Approach 2:
The sealing element is designed as a simpler, more cost-effective component compared to a long grouted skirt. It provides the necessary sealing function without the high fabrication costs associated with long grouted skirts, making the overall solution more economical.
3Reliability
If precise alignment of flanges is required for proper bolting and sealing, then sealing integrity is improved, but alignment difficulty and installation complexity increase
Solution Approach 1:
The sealing element is designed with material properties and geometric parameters that allow it to accommodate alignment tolerances. The compressible nature and specific cross-sectional geometry of the sealing element enable it to maintain sealing integrity even when flange alignment is not perfectly precise, thereby reducing alignment difficulty.
Solution Approach 2:
The sealing element is made from composite or specially formulated material that combines sealing effectiveness with tolerance to misalignment. This material composition allows the sealing element to deform and adapt to slight misalignments while maintaining fluid-tight sealing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective, quicker installation process with enhanced sealing integrity and reduced weather downtime risks by ensuring precise alignment and a reliable water-tight seal, even under varying installation conditions.
Implementation Method 1
the sealing element is a compressible sealing element sandwiched between the skirt and the collar
Data Source
AI summary
A bolted joint of an offshore structure comprises first and second connecting elements, wherein the first connecting element forms part of an offshore tower or an offshore platform and the second connecting element forms part of a foundation structure. The first connecting element comprises a first flange and the second connecting element comprises a second flange, wherein the first and second flanges abut each other with through holes in alignment. One of the first and second connecting elements comprises an outer peripheral skirt covering a butt joint between the first and second flanges and defining an outer annular space surrounding the butt joint, One of the first and second connecting elements comprises a peripheral collar, the skirt and the collar confining the annular space, the sealing element being a compressible sealing element sandwiched between the skirt and the collar.