Pipe Coupling Shrink-Fitted Collar Reduces Pin Thickness
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Solution Overview
Problem
Threaded and coupled connections for risers and flowlines in the oil and gas industry face limitations as they require a thicker pin component to accommodate external metal-to-metal seals, which restricts their adaptability to various connection profiles and increases material costs.
Innovation Solution
A pipe connector design featuring a tubular pin member with an annular collar and a tubular box member, where the collar is shrink-fitted onto the pin member, allowing for a thinner walled construction while maintaining the advantages of threaded and coupled connections, including high axial preload and improved fatigue characteristics, and accommodating different connection profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded and coupled connections use external metal-to-metal seals, then sealing reliability is improved, but pin component thickness increases
Solution Approach 1:
A separate rigid external seal/support ring is introduced as an intermediary component between the pin and box connectors. This ring provides the necessary metal-to-metal sealing surface and structural support, allowing the pin component itself to be thinner while maintaining sealing reliability. The seal ring acts as a mediator that decouples the sealing function from the structural pin component.
Solution Approach 2:
The connection system is segmented into distinct functional components: the pin connector, the box connector, and a separate seal/support ring. This segmentation allows each component to be optimized for its specific function - the pin and box for structural connection, and the separate ring for sealing and support, thereby reducing the thickness requirement of the pin component.
2Reliability
If pin component thickness is increased to accommodate external seal, then sealing capability is improved, but adaptability to connection profiles decreases
Solution Approach 1:
By separating the sealing function into a dedicated external seal ring, the pin component can be designed with thinner walls to accommodate various connection profiles. The seal ring can be independently selected and positioned to match different profile requirements while maintaining consistent sealing capability.
Solution Approach 2:
The external seal/support ring serves multiple functions simultaneously: providing metal-to-metal sealing, offering structural support, and enabling adaptability to different connection profiles. This multi-functional component allows the same basic pin and box connector design to be used across various applications without requiring thicker pin walls.
3Ease of manufacture
If threaded and coupled connections are used instead of welded forged connections, then cost and sour service compliance are improved, but material thickness requirements increase
Solution Approach 1:
The external seal/support ring acts as a mediator that enables threaded and coupled connections to achieve the sealing reliability previously only attainable with thicker welded forged connections. This allows the use of thinner-walled components while maintaining sour service compliance and reducing manufacturing costs through the advantages of threaded connections.
Solution Approach 2:
The introduction of the external seal ring changes the design parameters of the connection system, allowing thinner wall thicknesses to achieve the same sealing and structural performance. This parameter change enables the adoption of threaded and coupled connections with reduced material requirements while maintaining compliance with sour service standards.
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
Enables the use of threaded and coupled connections in a wider range of applications, reducing material costs and enhancing the connector's fatigue performance and adaptability, while maintaining the benefits of MERLIN-type connectors such as high axial preload and metal-to-metal sealing.
Implementation Method 1
the collar being shrink fitted on to the pin member internally/adjacent/above of the peripheral outer surface
Data Source
Figure 1
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Figure 4
AI summary
A pipe connector (12) comprising tubular pin member (13) having an outer peripheral surface (15) and a tubular box member (26) having an inner peripheral surface corresponding to the outer peripheral surface of the pin member and which overlies the outer surface of the pin member when the members are fully engaged together, the members being provided with inter engaging projections and grooves (16) on said peripheral surfaces for axially locking the members together when they are fully engaged together, the pin member further comprising an annular collar (18) shrink fitted onto the pin member (13) above of the peripheral outer surface (15), the collar comprising a shoulder (24) at one end of the collar adjacent the outer peripheral surface of the pin member, the arrangement being such that when the members are fully engaged together, the tubular box member abuts the shoulder of the annular collar.