Oil Pipe Threaded Joint With Asymmetrical Double Seals
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Solution Overview
Problem
Existing premium joints for oil and gas pipes with double seals fail to optimally differentiate between internal and external pressure sealing, leading to potential overstressing and galling of contact surfaces, and require complex coupling processes to ensure effective sealing across various conditions.
Innovation Solution
A threaded joint design featuring a female part with a conical internal surface and a male part with a proximal conical and distal convex seal surface, where the stresses complement each other to provide optimal sealing under both internal and external pressures, reducing the risk of galling and ensuring effective sealing across different loading conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If identical double seal configurations are used for both internal and external pressure sealing, then sealing is guaranteed in two zones, but one of the seals will be overstressed leading to accelerated galling of contact surfaces
Solution Approach 1:
The patent applies different seal configurations to different zones: the proximal seal uses a rounded section to cone surface configuration optimized for external pressure sealing, while the distal seal uses a cone to cone configuration optimized for internal pressure sealing. This local differentiation ensures each seal operates within optimal stress parameters, preventing overstressing and galling while maintaining sealing reliability in both zones.
Solution Approach 2:
The invention introduces asymmetry in the double seal configuration by using non-identical seal designs for proximal and distal zones. The proximal seal features a rounded section to cone surface geometry while the distal seal uses cone to cone geometry. This asymmetric design allows each seal to be optimized for its specific pressure condition, avoiding the galling problem that arises from symmetric identical seal configurations.
2Reliability
If complex coupling processes are used to ensure effective sealing across various conditions, then sealing effectiveness is improved, but the coupling process complexity increases
Solution Approach 1:
The patent incorporates preliminary action by pre-configuring the seal surfaces with specific geometries (rounded section to cone for proximal, cone to cone for distal) that automatically engage and seal at predetermined positions during the coupling process. The tapered threads and pre-shaped seal surfaces guide the coupling operation, ensuring seals form correctly without requiring complex external control or adjustment mechanisms.
Solution Approach 2:
The sealing surfaces are designed to self-seal through their geometric configuration. The rounded section to cone and cone to cone surfaces automatically generate the necessary contact pressure and sealing geometry when the pin and box are coupled, without requiring external intervention or complex coupling processes. The internal pressure also provides a self-sealing effect that expands the pin nose to enhance sealing.
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 asymmetrical double seal configuration effectively withstands both internal and external pressures, reduces the risk of galling, and simplifies the coupling process by distributing stress concentrations optimally, ensuring reliable sealing under various operational conditions.
Implementation Method 1
The seal is formed by a metal-to-metal intimate contact that has to withstand both external and internal pressures, axial loads and bending
Implementation Method 2
the internal pressure improves the sealing, since it tends to expand the pin nose, that is, it has a self-sealing effect
Data Source
AI summary
Threaded joint for oil and gas pipes, including a female part and a male part, the female part being a joint tubular body including a threaded coupling section, a seal section which prolongs the coupling section, the male part including a tubular body which includes a first section which external surface is threaded, a second sealing section including a seal surface which cooperates with the female part seal surface for sealing the joint, the sealing surface of the female part being made of conical sections, the sealing surface of the male part includes a proximal portion closer to the first section and a distal portion, the proximal section portion being a conical surface which forms a first seal with the sealing surface of the female part and the distal portion having a convex surface which forms a second seal with the sealing surface of the female part.