Slip-Joint Conduit Fitting for Subsidence Accommodation

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Solution Overview

Problem

Existing slip-joint technologies for connecting electrical conduits from underground service lines to building service boxes face challenges with misalignment, difficulty in installation due to close tolerances, and inability to accommodate lateral stress, leading to potential jamming and inoperativeness during subsidence.

Innovation Solution

A slip-joint design featuring a larger inside diameter conduit with significant clearance and a deformable sealing ring, allowing for lateral movement and misalignment between conduit sections, ensuring easy installation and effective sealing while accommodating subsidence forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If close tolerance is provided between conduit diameters to prevent insects and animals from accessing service box, then sealing effectiveness is improved, but lateral movement capability deteriorates causing installation difficulty

Engineering Contradiction:

Improvesealing effectivenessVSAvoidinstallation ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The conduit system is divided into multiple sections with expansion joints between them, allowing each section to be installed independently with standard tolerances while maintaining overall sealing through the expansion joint mechanism

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A flexible sealing ring made of elastomeric material is used to provide the sealing function, replacing the rigid close-tolerance fit approach. This flexible seal accommodates lateral movement while maintaining effectiveness against insects and animals

Inventive Principle:

Principle #30Flexible shells and thin films

2Adaptability or versatility

If close tolerance sliding fit is used between conduits to allow subsidence accommodation, then protection against ground settling is improved, but lateral stress resistance deteriorates causing jamming

Engineering Contradiction:

Improvesubsidence accommodationVSAvoidlateral stress resistance

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The flexible elastomeric sealing ring provides the subsidence accommodation through its ability to deform and maintain seal under vertical movement, while the rigid conduit sections maintain lateral strength to resist jamming forces

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The system combines rigid conduit materials (for lateral strength) with flexible elastomeric sealing material (for subsidence accommodation), creating a composite structure that exhibits both strength and adaptability

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If exact alignment of conduits is required for proper installation, then sealing precision is improved, but installation time increases significantly

Engineering Contradiction:

Improvealignment precisionVSAvoidinstallation time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The flexible sealing ring compensates for misalignment between conduit sections, allowing installation with standard alignment tolerances while maintaining effective sealing without requiring exact alignment

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

By dividing the conduit into sections connected by expansion joints with flexible seals, each section can be installed independently with reasonable alignment, eliminating the need for precise end-to-end alignment across the entire conduit run

Inventive Principle:

Principle #1Segmentation

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 solution enables convenient installation, prevents jamming, and maintains effective sealing and protection of electrical services during ground subsidence, reducing the need for special conduit sizes and manufacturing costs.

Implementation Method 1

A deformable sealing ring, such as made from an elastomeric material, is used to prevent passage of small animals or insects between the two conduit sections

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS7550669B2Slip-joint connection for electric service conduit to service boxes

Publication Date: 2009.06.23 RIZZUTO JR SALVATORE A

AI summary

A fitting is provided for slip fit adjustment of conduit leading from an electric service box on a building to an underground electric service line to allow for subsidence of the ground level without excessive force on the service box even when sections of the conduit are not in alignment.