Design and analysis of non-threaded drill pipe connector.

Thakur, Joshua Omar

Abstract

This thesis determines the feasibility and application opportunities of a Snap-Latch Ring design based on the Pin and Box non-threaded connectors design. Modern drill pipes are connected by rotary threaded shouldered connections that have been prone to failure, leading to fatal accidents on the drilling deck. The proposed connection mechanism aims to improve engagement and disengagement time of pipes by 50% as well as being a safer connection alternative. This research involved studying the existing design for Pin and Box connectors from a previous study (Phase 1) and designing applicable solutions for the Snap-Latch Ring, which is a key component for the engagement and connection of the pipe connectors. The Snap-Latch Ring design needs to be able to withstand high tensile loads from operational use as well as possessing magnetic properties to enable actuation of the rings. Finite Element Analysis (FEA) was conducted using the ANSYS Workbench software package to identify the maximum stress and deformation behaviors for the Snap-Latch Ring prototypes that were designed. The initially proposed Snap-Latch Ring parameters were optimized, running several simulations to identify scope for further improvement. The Snap-Latch Ring prototypes were shown to fail under the maximum tensile load target; however, all three components were simulated at a range of tensile loads to identify a safe working range of loads for the given components. Furthermore, a few scaled prototypes were manufactured using both 3D printing methods (plastic prototypes) as well as CNC machining (metal prototypes) to manufacture Pin, Box and Snap-Latch Ring prototypes. The thesis concludes that, within the current limitations with respect to all three components (Pin connector, Box connector and Snap-Latch Ring), the stress limit of the entire system is limited to that of the Snap-Latch ring. The Pin and Box connections - due to their teeth-like geometry features - handle torsional stress. Hence the safe operational force that can be applied is 1,130kN (or 254,034 lbs), which is 13.2% of the original suggested maximum tensile force 8,565kN (or 1,925,541 lbs). Hence the application of the current design needs reconsideration. As the Snap-Latch ring is located (sandwiched) between the Pin and Box connectors, the only means of actuation is by non-contact forces. This is only possible through magnetic actuation. However, the surface area of the ring is too small to be attracted with the required pull force. The thesis further expands over the key considerations to be overcome for future work. It must be understood that there are certain technological restraints in the analyzed design - such as the maximum tensile yield strength, magnetic permeability and having these two properties not become affected by the harsh corrosive conditions existing downhole. Pin and Box design could be altered to handle maximum shear contact between the components by changing the geometry, as more shear contact area means more stress distribution and better stress and deformation performance.

Citation

THAKUR, J.O. 2022. Design and analysis of non-threaded drill pipe connector. Robert Gordon University, MRes thesis. Hosted on OpenAIR [online]. Available from: https://doi.org/10.48526/rgu-wt-2271554

• Thesis Type: Thesis
• Deposit Date: Mar 14, 2024
• Publicly Available Date: Mar 14, 2024
• DOI: https://doi.org/10.48526/rgu-wt-2271554
• Keywords: Pipelines; Stress testing; Shearing
• Public URL: https://rgu-repository.worktribe.com/output/2271554
• Award Date: Jan 31, 2022