Collet Style Tubular Connection for Riser Safety
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Solution Overview
Problem
Current methods for connecting drilling riser pipes require manual manipulation with wrenches or stud tensioning devices, posing safety risks and increasing costs due to prolonged exposure to drilling slots and high torque requirements, especially for larger diameters.
Innovation Solution
A subsea riser assembly using a radially contractible collet or ring with constant diameter threads and an outer sleeve that secures tubular members with fewer turns, eliminating the need for wrenches and reducing specialty equipment reliance, while generating higher radial and axial preload forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bolted flange type connectors or radially oriented screws are used to connect drilling riser joints, then the connection can withstand substantial loads, but personnel must be in close proximity to drilling slots for prolonged periods and manipulation with wrenches is required
Solution Approach 1:
The connection system uses self-aligning features including a pin end with outer diameter grooves that mate with inner diameter grooves in the box end, and a collet with constant diameter threads that automatically center and engage during insertion, eliminating the need for manual alignment and wrench manipulation
Solution Approach 2:
The invention replaces the traditional wrench-based mechanical fastening system with a self-actuating threaded collet mechanism that secures through rotational engagement of constant diameter threads, eliminating the need for external wrench tools and manual positioning
2Reliability
If screw type box and pin ends are used to connect riser members, then the connection can be secured, but multiple turns of rotation are required which increases the time for connection
Solution Approach 1:
The collet is pre-configured with constant diameter threads and engagement features that are ready to immediately engage with the pin end grooves upon insertion, eliminating the need for preliminary alignment or positioning steps
Solution Approach 2:
The connection mechanism is divided into distinct functional segments: the pin end with outer diameter grooves, the box end with inner diameter grooves, and the collet with constant diameter threads, allowing each segment to perform its specific function efficiently and independently
3Reliability
If conventional direct threaded make-up is used for larger riser diameters, then the connection can be made, but extremely high torque requirements are needed
Solution Approach 1:
The invention transitions from conventional axial threaded engagement to a radial contraction mechanism where the collet contracts radially inward to secure the pin end, converting the force requirement from high axial torque to controlled radial compression through constant diameter thread engagement
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 enables rapid, safe, and cost-effective connection of tubular members with reduced personnel exposure to drilling slots, lower capital costs, and faster assembly times, while providing enhanced preload forces compared to existing systems.
Implementation Method 1
The radially contractible member has constant diameter threads on an outer diameter of the member. The outer sleeve has threads on an inner diameter that fully engage the threads on the outer diameter of the radially contractible member
Data Source
AI summary
A collet assembly connects two tubular members with a rotation of an outer sleeve. The collet assembly includes a first tubular member with a grooved outer diameter end. The end is inserted into a collet having grooved inner and outer diameter surfaces, and an outer annular sleeve is threaded onto the collet. A grooved outer diameter end of a second tubular member is inserted into the collet. The outer annular sleeve is rotated relative to the collet. The rotation causes the collet to partially disengage from the outer annular sleeve and fully engage the grooves of the ends of the first tubular member and the second tubular member, thereby securing the first tubular member to the second tubular member.