Double-Shouldered Drill Pipe Connection for Large-ID Torque Transfer
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Solution Overview
Problem
Conventional double-shouldered connections for drilling tubulars with large inside diameters exhibit significantly lower torque transmission capabilities compared to those with small inside diameters, necessitating an improved design to enhance torque transmission for larger diameter drill pipes.
Innovation Solution
A double-shouldered threaded connection design featuring a tubular box section with a tapered box portion, first and second torque shoulders, and a threaded collar, along with a threaded insert, where the internal threads of the tapered box portion have a right-hand direction and the internal collar threads and external insert threads have a left-hand direction, allowing for increased torque transmission capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional double-shouldered connections are used for drill pipes with large inside diameter, then the connection structure is simple and easy to manufacture, but the torque transmission capability is significantly reduced
Solution Approach 1:
The connection structure is divided into multiple functional segments: a tapered box portion with internal threads for the pin connection, a threaded collar with internal collar threads, and a threaded insert with external insert threads. This segmentation allows each component to perform its specific function optimally, with the tapered portion providing torque transmission and the collar/insert assembly providing the large diameter adaptation, thereby resolving the contradiction between torque capability and structural simplicity.
Solution Approach 2:
The threaded insert is nested within the threaded collar, which itself is part of the box section. This nested arrangement allows the complex multi-threaded structure to be compactly integrated within the existing connection geometry, maintaining ease of assembly while achieving enhanced torque transmission capability for large diameter drill pipes.
2Area of moving object
If the box section has a large inside diameter, then the drill pipe can accommodate larger drilling tools, but the torque transmission capability of the connection is reduced
Solution Approach 1:
The connection structure implements local quality by creating a tapered box portion with specifically engineered internal threads in the critical torque transmission zone. The taper angle and thread geometry are optimized locally to maximize torque capacity, while the rest of the pipe maintains its large inside diameter for tool accommodation. This localized optimization resolves the contradiction between large diameter and torque capability.
Solution Approach 2:
The invention changes key geometric parameters of the connection: introducing a taper angle to the box portion, specifying thread directions (right-hand for tapered box, left-hand for collar and insert), and defining specific shoulder positions. These parameter changes enable the connection to transmit higher torque despite the large inside diameter, resolving the contradiction between tool accessibility and connection strength.
Data Source
AI summary
A threaded connection for drilling tubulars includes a tubular box section having a sidewall. The box section has a tapered box portion of an inner surface of the sidewall between a first end and a second end. The tapered box portion has internal threads, a first torque shoulder on a first side of the tapered box portion, and a second shoulder on a second side of the tapered box portion. A threaded collar having internal collar threads is positioned between the second end and the second shoulder. A threaded insert having a tubular body with an inner surface and an outer surface having external insert threads is configured for threadably connecting to the internal collar threads. A direction of the internal threads of the tapered box portion is opposite to a direction of the internal collar threads and the external insert threads.