Offshore Pin Joint Assembly for Corrosion-Resistant Frame Connections

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Solution Overview

Problem

The joining of columns and braces in offshore frame constructions is challenging due to complex geometry, leading to moderate-quality welding, geometrical stress concentrations, and increased material requirements, resulting in a costly and time-consuming assembly process.

Innovation Solution

A pin joint connection using a fork part, an ear part, and a pin, with optional corrosion-resistant linings and interference fits, allows for pre-fabrication and faster assembly, reducing maintenance needs and improving structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If welded joints are used to connect columns and braces in offshore frame constructions, then the structural strength and stiffness are improved, but the assembly time and cost increase significantly due to complex geometry requiring hand welding

Engineering Contradiction:

Improvestructural strengthVSAvoidassembly time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The joint is divided into separate pre-fabricated components (node casting with integrated reinforcement elements) that can be manufactured independently and then assembled quickly on-site, eliminating the need for time-consuming in-situ welding of complex geometries

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The node castings and reinforcement elements are pre-fabricated in controlled manufacturing environments before assembly, allowing for higher quality control and faster on-site installation without the need for extensive welding operations in the field

Inventive Principle:

Principle #10Preliminary action

2Strength

If welded joints are used to connect columns and braces, then the structural integrity is improved, but the manufacturing cost increases due to in-situ welding requirements

Engineering Contradiction:

Improvestructural integrityVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The joint system is segmented into pre-fabricated node castings and reinforcement elements that can be manufactured separately in cost-effective facilities, reducing the need for expensive in-situ welding operations at offshore locations

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The welding process is replaced with a mechanical connection system using pre-fabricated node castings and reinforcement elements that can be assembled without welding, eliminating the high costs associated with in-situ welding operations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If complex geometry joints are welded, then the structural connection strength is improved, but geometrical stress concentrations increase leading to over-dimensioning

Engineering Contradiction:

Improveconnection strengthVSAvoidgeometrical stress concentrations

Core Design Contradiction:

StrengthVSStress or pressure

Solution Approach 1:

The node casting incorporates locally optimized reinforcement elements positioned at specific locations to address stress concentrations, allowing the joint to maintain strength while reducing overall material usage and avoiding over-dimensioning

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The complex joint geometry is replicated through precision casting of node castings that incorporate integrated reinforcement elements, achieving consistent structural properties without the stress concentrations associated with welded assemblies

Inventive Principle:

Principle #26Copying

4Loss of time

If bolted connections are used to join columns and braces, then the assembly time is reduced, but maintenance requirements increase due to potential corrosion and loosening

Engineering Contradiction:

Improveassembly timeVSAvoidmaintenance needs

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

Reinforcement elements act as intermediaries between the node casting and the structural members, providing a robust mechanical connection that reduces maintenance needs compared to direct bolted connections while still enabling fast assembly

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The joint system combines different materials and construction approaches (node casting, reinforcement elements, and structural members) to create a connection that offers both rapid assembly and long-term reliability without the maintenance issues of traditional bolted connections

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS20220120050A1Structural joint for offshore constructions and a method for the assembly of such offshore frame constructions and use of such structural joint

Publication Date: 2022.04.21 STIESDAL OFFSHORE TECH AS

AI summary

Various embodiments of the present disclosure are directed to offshore frame construction. In one example embodiment, an offshore frame construction is disclosed including structural members and a structural joint connecting the structural members. The structural joint includes a fork part, an ear part, and a pin, where the fork part and the ear part includes a bore, and the pin is inserted into the bore. The pin has a non-corroding surface that is a cladding or bushing welded or shrunk or glued or otherwise affixed to the pin which consists of a different material, or the non-corroding surface is continuous with the pin and the pin consists of the non-corroding material. In some specific embodiments, the bore includes a sliding surface, which is fitted with a liner acting as a bearing, and the bearing is an elastomeric bearing.