Segmented Stop Collar for Narrow Annulus Tubular Engagement
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Solution Overview
Problem
Current stop collars and centralizers in the oil and gas industry face issues with stress corrosion, inadequate axial load resistance, and assembly challenges due to poorly tolerated tubular diameters, leading to reduced holding ability and increased risk of component failure, especially when assembled by unskilled labor and in narrow annulus configurations.
Innovation Solution
A one-piece stop collar and centralizer design featuring a cylindrical band with arcuate portions and S-shaped connecting portions, utilizing micro-alloy steel and segmental cut forms that can distort to accommodate diameter variations, providing secure engagement through interlocking teeth and a ratchet mechanism, and coated internal diameters to reduce stress corrosion, allowing for easier assembly and improved axial load resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple radially disposed screws or wedges are used to increase axial holding ability, then axial load resistance is improved, but stress corrosion potential increases dramatically
Solution Approach 1:
The stop collar is divided into multiple segmental portions (first, second, third portions) that can independently distort to accommodate tubular diameter variations. This segmentation allows each portion to contribute to axial load resistance without requiring multiple radially disposed screws or wedges that would cause stress corrosion.
Solution Approach 2:
The stop collar portions are designed to be distortable rather than rigid. The arcuate portions can dynamically adjust their shape to fit different tubular outer diameters within the tolerance range, providing consistent axial load resistance without penetrating the tubular surface with multiple fasteners.
2Strength
If the number of radially disposed screws is increased to achieve desired axial holding forces, then axial load resistance is improved, but the complexity of assembly increases and assembly quality becomes difficult to control
Solution Approach 1:
The multiple functional elements (axial load resistance, diameter accommodation, positioning) are merged into a single integrated stop collar structure with segmental portions. This eliminates the need for separate radially disposed screws or wedges, simplifying assembly to a single operation while maintaining control over assembly quality.
Solution Approach 2:
The stop collar portions automatically adjust and distort to fit the tubular member without requiring precise assembly procedures. The self-distorting nature of the arcuate portions eliminates the need for skilled labor to control torque application or thread lubrication, as the structure adapts itself to the tubular dimensions.
3Strength
If traditional stop collars with protruding screws or wedges are used, then axial load resistance is achieved, but the use in narrow annulus configurations is restricted
Solution Approach 1:
The protruding fasteners (screws or wedges) are extracted from the design. Instead, the stop collar uses integrated distorable arcuate portions that provide axial load resistance without external protrusions, enabling use in narrow annulus configurations where traditional fasteners would interfere.
Solution Approach 2:
The stop collar portions are designed as flexible, distorable elements rather than rigid structures with protrusions. This flexibility allows the stop collar to conform to narrow annulus spaces while maintaining axial load resistance through the distortion mechanism of the arcuate portions.
Data Source
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AI summary
A stop collar or like device is formed in one piece to have a portion for a tool to be attached. Movement of the tool allows the collar to be drawn tightly into engagement onto a pipe or other tubular member. A bow centraliser has alternate bows longitudinally offset to reduce initial insertion force. The centraliser may be formed to have end bands of the type used in the stop collar.