Interference-Fit Stop Collar for Tubular Positioning
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Solution Overview
Problem
Conventional stop collars are too large in outer diameter for low-clearance applications, lack sufficient load capacity, and often damage tubulars due to inadequate contact, requiring heavy machinery and skilled labor for installation, and are not compatible with expandable tubulars or premium-grade materials.
Innovation Solution
A stop collar design featuring a base with extending fingers and a sleeve that forms an interference-fit, allowing for a large grip area without deforming the tubular, and can be installed at any position along the tubular string using a method that includes interference-fit and self-tightening mechanisms, compatible with varying tubular diameters and materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional stop collars are used to secure devices on tubulars, then they provide basic positioning function, but they are too large in outer diameter for low-clearance applications and lack sufficient load capacity
Solution Approach 1:
The stop collar comprises a base with fingers that extend radially outward, and a sleeve that receives these fingers in an interference fit. The fingers are nested within the sleeve's bore, creating a compact structure where the load-bearing fingers are contained within the outer diameter defined by the sleeve, achieving high load capacity without excessive outer diameter
Solution Approach 2:
The base is segmented into multiple fingers that extend radially outward. These segmented fingers distribute the load capacity across multiple contact points with the tubular, increasing overall strength while maintaining a compact outer diameter profile that fits low-clearance applications
2Reliability
If conventional stop collars are installed on tubulars, then they provide positioning function, but they often damage tubulars due to inadequate contact
Solution Approach 1:
The fingers are designed with specific surface characteristics and contact geometries that concentrate the attachment force on localized regions of the tubular. The interference fit between the sleeve and fingers creates localized high-strength bonding, ensuring secure attachment without requiring excessive force that would damage the tubular
Solution Approach 2:
The stop collar combines different materials with complementary properties: the base and fingers are made of a material optimized for gripping the tubular, while the sleeve is made of a material that provides the interference fit. This composite structure achieves reliable attachment through the synergistic combination of material properties, securing the device without damaging the tubular
3Ease of manufacture
If conventional stop collars are installed using heavy machinery and skilled labor, then installation can be completed, but it requires heavy machinery and skilled labor which increases cost and complexity
Solution Approach 1:
The interference fit between the sleeve and fingers creates a self-tightening mechanism that secures the stop collar to the tubular without requiring external fastening equipment. The design enables field installation with portable equipment, eliminating the need for heavy machinery and specialized installation procedures
4Adaptability or versatility
If conventional stop collars are designed for fixed positions, then they provide stable positioning, but they are not compatible with expandable tubulars or premium-grade materials
Solution Approach 1:
The fingers are designed to flex and adapt to the tubular's surface, and the interference fit allows for dynamic adjustment during installation. This dynamic design enables compatibility with expandable tubulars that change diameter, while the final interference-fit configuration provides stable positioning once installed
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 superior load capacity without marking or damaging the tubular, is compatible with expandable tubulars, and can be installed in the field with portable equipment, eliminating the need for heavy machinery and skilled labor.
Implementation Method 1
a sleeve with a bore receivable onto the tubular and onto the fingers extending from the base in an interference-fit
Implementation Method 2
The elasticity of the sleeve material maintains a grip on the portion of the set of fingers within the bore of the sleeve
Data Source
AI summary
A stop collar is assembled using a method including the steps of receiving a bore of a base having a set of fingers extending along an exterior of a tubular, receiving a bore of a sleeve onto the tubular adjacent the set of fingers, and receiving the sleeve onto the set of fingers in an interference-fit. In alternate embodiments, the base comprises a plurality of angularly distributed fingers and/or the base comprises a gap to permit conformance of the base to the tubular. A fingerless base may cooperate with one or more separate fingers to form a base. In an embodiment of the method, the sleeve may be thermally expanded prior to the step of receiving the sleeve onto the set of fingers. The sleeve may be heated to expand the bore prior to being received onto the set of fingers.