Plastic Pipe Joint With Threaded Seal

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Solution Overview

Problem

Existing methods for joining plastic pipes, especially for pressurized fluids like drinking water, are laborious, complex, and expensive, often requiring skilled labor and machinery, and can lead to stagnation points and contamination due to protuberances and deteriorating gaskets.

Innovation Solution

A plastic pipe joint featuring a male end with an external thread and a female end with an internal thread and shoulder, incorporating a flexible sealing lip that deforms to create a tight seal when assembled, allowing for simple and strong connections without the need for complex on-site procedures or expensive equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If welding is used to join plastic pipes, then a strong and sealed connection is achieved, but the process becomes laborious, complex, and expensive requiring skilled labor and machinery

Engineering Contradiction:
Improveconnection strengthVSAvoidjoining process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The joining process is segmented into two independent parts: threading (which can be done during pipe manufacturing) and assembly (which is simple field operation). This separates the complex machining operations from the simple field assembly, resolving the contradiction between strong connection and process complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The threads are pre-formed on the pipes during manufacturing rather than being created on-site. This preliminary action transfers the complex machining operation to the factory setting where it can be done with proper equipment, leaving only simple assembly for field workers.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If welding is used to join plastic pipes, then a sealed connection is achieved, but protuberances and protrusions arise inside the pipe that interfere with water flow and form stagnation points

Engineering Contradiction:
Improveseal reliabilityVSAvoidwater flow interference
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

Instead of fusing pipes together which creates internal protrusions, the invention uses external threading where the sealing surface is on the outside of the male pipe. This inverts the traditional approach, placing the sealing function external to the water flow path, thus eliminating flow interference while maintaining seal reliability.

Inventive Principle:
Principle #13The other way round (Inversion)

3Ease of operation

If bell joints with gaskets are used to connect pipes, then simple assembly is achieved, but the connection is not suitable for highly pressurized fluids and gaskets deteriorate over time

Engineering Contradiction:
Improveassembly simplicityVSAvoidconnection reliability under pressure
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention replaces the deteriorating elastomeric gasket with a permanent metal thread seal. The threaded connection is designed to maintain its sealing capability throughout the service life of the piping system, eliminating the need for periodic gasket replacement while withstanding high pressures.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The joint uses a composite approach combining metal threading for structural strength and pressure resistance with a sealing mechanism that maintains reliability under high pressure, unlike single-material gasket solutions that deteriorate over time.

Inventive Principle:
Principle #40Composite materials

4Reliability

If gaskets are used in bell joints for drinking water, then sealing is achieved, but expensive elastomeric materials must be used that deteriorate and weaken requiring maintenance

Engineering Contradiction:
Improveseal effectivenessVSAvoidmaterial cost and maintenance
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces expensive, deteriorating elastomeric gaskets with a permanent metal thread seal that maintains its sealing capability throughout the service life of the piping system, eliminating the need for periodic replacement and reducing long-term costs.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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

Enables quick, strong, and tight connections suitable for high-pressure fluids, reducing assembly complexity and costs while ensuring a complete wet seal without the need for skilled labor or specialized machinery, and minimizing contamination risks.

Implementation Method 1

The inner wall of the second female end is provided with at least one flexible and/or deformable sealing portion... In the assembled configuration, the sealing portion abuts, being deformed, the abutment portion so as to carry out with the latter a sealing portion for the wet seal of the joint

Methodology Applied
Scientific EffectDeformation: Deformation

Data Source

PatentEP3062009B1Plastic tube and plastic tube joint
Publication Date: 2019.01.09 IPM
  • EP3062009B1 patent drawingFigure 1~2
  • EP3062009B1 patent drawingFigure 3~5

AI summary

A plastics pipe joint, in particular polyolefin plastic pipe, comprises a first tubular element (1) provided with a first male end (3) having an external wall (13) provided with an external thread (4) and a second tubular element (2) provided with a second female end (5) having an inner wall (15) provided with an internal thread (6) and an internal shoulder (7), the first male end (3) being screwable into the second female end (5) along a longitudinal axis (X) in an assembled configuration (A) for joining the first tubular element (1) and the second tubular element (2) so as to form the joint (100); the inner wall (15) of the second female end (5) is provided with at least one flexible and/or deformable sealing portion (8) that is interposed between said internal shoulder (7) and said internal thread (6); the external wall (13) of said first male end (3) comprises an abutment portion (9) that is interposed between a front edge (11) of the first male end (3) and the external thread (4); the sealing portion (8) is integral with the second tubular element (2) and in the assembled configuration (A) is bent by, and abuts, the abutment portion (9) so as to carry out with the latter a sealing portion (10) for the wet seal of said joint (100).