Dual-Member Pipe Assembly for HDD Torque and Fluid Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In small diameter horizontal directional drilling operations, existing dual-member drill strings face challenges with torque and thrust forces, and there is a need for improved fluid delivery to the boring tool for cooling and cutting material removal.
Innovation Solution
A dual-member pipe assembly with a hollow inner member and a removable collar that allows axial movement, forming a torque-transmitting inner drive train and enhancing fluid flow through the annular space between the inner and outer members, while maintaining structural integrity and alignment capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a solid rod is used as the inner member in small diameter drilling operations, then space constraints are satisfied and torque and thrust forces can be handled, but fluid flow to the boring tool is limited
Solution Approach 1:
The inner member is segmented into a solid rod portion for torque transmission and a hollow portion for fluid flow. This segmentation allows the inner member to simultaneously handle mechanical loads while providing adequate fluid passage to the boring tool, resolving the contradiction between limited space and fluid delivery requirements.
Solution Approach 2:
The hollow inner member is nested within the outer member, creating an annular space that serves as an additional fluid flow pathway. This nested configuration maximizes fluid delivery capacity without increasing the overall diameter of the drill string, thus satisfying both space constraints and fluid flow requirements.
2Quantity of substance
If a hollow inner member is used to increase fluid flow, then cooling and cutting performance improve, but structural integrity under torque and thrust forces may be compromised
Solution Approach 1:
The inner member is constructed as a composite structure combining a solid rod core with a hollow tubular portion. This composite design provides both the mechanical strength needed to withstand torque and thrust forces and the hollow section required for fluid flow, thereby maintaining structural integrity while enabling improved cooling and cutting performance.
Solution Approach 2:
The inner member is divided into functional segments: a solid rod portion that bears mechanical loads and a hollow tubular portion that conducts fluid. This segmentation allows each portion to optimize its specific function while the combined structure maintains overall structural integrity under drilling conditions.
3Ease of operation
If the inner member is made axially movable relative to the outer member, then alignment and steering capabilities are improved, but control of relative movement becomes more complex
Solution Approach 1:
The inner member is designed with axial movability relative to the outer member, allowing dynamic adjustment of the inner member's position along the axis. This dynamic capability enables improved alignment and steering control during drilling operations, while the movability is constrained within specific limits to prevent excessive complexity in control mechanisms.
Data Source
AI summary
A pipe assembly used in horizontal directional drilling operations. The pipe assembly has an outer member, an inner member, and first removable collar. The inner member has a polygonal outer profile of uniform shape along its length and is partially contained within the outer member. The first removable collar is supported on the inner member within the outer member and limits relative axial movement of the inner member and the outer member.