Shoulder Ring Structure for High-Torque Threaded Pipe Connections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing threaded connections in the oil and gas industry face challenges in withstanding excessive torque forces, particularly in lateral wells with thin shale formations, leading to thread failure and reduced torque capacity due to plastic yielding and wear, which affects the mechanical integrity and sealability of the connections.
Innovation Solution
The use of dimensioned torque rings with varying axial lengths and beveled surfaces within the J-space of threaded couplings to balance hoop stresses, increase torsional resistance, and maintain sealability by ensuring proper alignment and contact between pin and ring faces, allowing for multiple make and break cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional threaded connections are used without torque rings, then the connection structure is simple and cost-effective, but the torque capacity is insufficient and thread failure occurs under excessive torque forces
Solution Approach 1:
A torque ring is introduced as an intermediary component between the pin and box threads. The torque ring receives and distributes torque forces, preventing direct thread failure while maintaining the overall threaded connection structure. The ring acts as a mediator that protects the threads from excessive stress concentrations.
Solution Approach 2:
The torque ring provides localized reinforcement at critical stress points within the threaded connection. By concentrating strength where needed (at the thread root and contact surfaces) rather than uniformly throughout the entire connection, the design achieves higher torque capacity without proportionally increasing overall complexity.
2Strength
If floating shoulder rings are used to increase torque capacity, then the torque withstand ability improves, but the axial stress on the inside of bends increases due to additional axial force required to push the pipe string through
Solution Approach 1:
The torque ring is designed with the ability to dynamically adjust its position and contact pressure based on applied torque. As torque increases, the ring naturally shifts to optimize load distribution, allowing the connection to adapt to varying operational conditions without requiring additional axial force to maintain stress balance.
Solution Approach 2:
The torque ring's geometric parameters (such as contact surface area, thickness, and position) are optimized to change the stress distribution characteristics. By carefully selecting these parameters, the ring increases torque capacity while minimizing adverse effects on axial stress distribution in bent pipe sections.
3Reliability
If tapered threads are used in threaded connections, then the connection achieves self-tightening and sealability, but plastic yielding and wear occur under repeated make and break cycles, reducing torque capacity
Solution Approach 1:
The torque ring is positioned in advance within the threaded connection to cushion and absorb the effects of repeated make and break cycles. It protects the tapered threads from plastic yielding and wear by providing a durable contact surface that can withstand cyclic loading, thereby extending the service life while maintaining sealability.
Solution Approach 2:
The torque ring is designed as a sacrificial component that can be replaced more easily and economically than the entire threaded connection assembly. By concentrating wear on the relatively simple torque ring rather than the complex tapered threads, the system extends the service life of the main connection while allowing periodic replacement of the wear ring.
Data Source
Figure 1~2a
Figure 3~5b
Figure 6a~6c
AI summary
A coupled pipe connection system may include a coupling with internal threads adapted for joining two pipe sections by threaded engagement of external pipe threads with the internal coupling threads. A torque ring may be disposed within the coupling and between the first pipe and the second pipe. The torque ring may an outer cylindrical surface, at least a portion of which may include a plurality of tapered threads engaged with and tapered to match a mid-length axial section / J-space of the inner threads of the coupling. Annular faces of the torque ring may be beveled inwardly or outwardly and adapted for mating engagement with corresponding beveled annular faces of the pipe ends. Torque rings of gradually decreasing axial lengths may be incrementally swapped out as the number of make-up cycles increases. Couplings having internal shoulders of gradually decreasing axial lengths may be used instead of torque rings.