Slotted Polymer Pipe Lining for Gas Venting and Buckling Prevention

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Solution Overview

Problem

Existing solutions for preventing buckling of internal linings in pipelines during depressurization due to gas accumulation are either expensive, complex, or prone to mechanical weakness and corrosion, and fail to efficiently manage pressure differentials.

Innovation Solution

A polymer lining with strategically designed slots that extend parallel to the pipeline's longitudinal axis, allowing gas evacuation into the pipeline during depressurization, minimizing dirt ingress and maintaining structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a polymer protective lining is used to prevent corrosion, then manufacturing cost is reduced compared to alloy steel lining, but the lining becomes permeable to gases allowing gas accumulation under the lining

Engineering Contradiction:
Improvemanufacturing costVSAvoidgas tightness
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent intentionally incorporates slots (controlled porosity) into the polymer lining to allow gas permeation. This resolves the contradiction by transforming the harmful permeability into a controlled feature that prevents gas accumulation and buckling, while maintaining the cost advantage of polymer materials over alloy steel lining.

Inventive Principle:
Principle #31Porous materials

2Strength

If the polymer lining is made thicker to prevent buckling during depressurization, then structural stability is improved, but gas accumulation pressure increases the risk of local collapse

Engineering Contradiction:
Improveresistance to bucklingVSAvoidgas accumulation pressure
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent extracts gas from the interstitial space between the lining and pipe through slots, channels, or perforations. This removes the harmful gas accumulation that causes buckling and collapse, allowing the lining to maintain adequate thickness for structural stability without suffering from excessive gas pressure.

Inventive Principle:
Principle #2Taking out (Extraction)

3Productivity

If slots are made open on the internal face to allow gas evacuation, then gas discharge efficiency is improved, but dirt and debris can ingress through the slots

Engineering Contradiction:
Improvegas evacuation efficiencyVSAvoiddirt ingress
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent creates asymmetric slot configurations where the slot geometry differs between the internal and external faces. This allows gas to escape efficiently through the open internal face while the asymmetric design (combined with fluid dynamics) prevents dirt and debris from entering, resolving the contradiction between evacuation efficiency and contamination prevention.

Inventive Principle:
Principle #4Asymmetry

4Strength

If adhesive coating is applied to increase adhesion between lining and pipe, then resistance to collapse is improved, but implementation complexity and manufacturing cost increase

Engineering Contradiction:
Improveadhesion strengthVSAvoidimplementation complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent enables the lining to self-support its position and resist collapse through the pressure differential created by gas evacuation pathways. The slots and channels allow the lining to maintain its structural integrity through pressure management rather than relying on adhesive coatings, eliminating the need for additional adhesive application steps and reducing implementation complexity.

Inventive Principle:
Principle #25Self-service

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

Effectively prevents buckling and maintains pipeline integrity by efficiently evacuating gas, reducing pressure differentials, and minimizing mechanical stress on the lining.

Implementation Method 1

the polymer lining has the disadvantage of being permeable to gases and vapors from the fluids being transported. Also, in practice, gas tends to penetrate the polymer material and pass through the protective lining to lodge in the interstitial space between the lining and the internal wall of the steel tube.

Methodology Applied
Scientific EffectPermeation: Permeation

Implementation Method 2

A pressure differential is then created with an overpressure on the side of the interstitial space, with a risk of the appearance of buckling or local collapse of the protective liner.

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP4449004B1Fluid transport pipe having a steel tube with a protective lining provided with slots for discharging gas built up under the lining
Publication Date: 2025.09.03 SAIPEM SA
  • EP4449004B1 patent drawingFigure 1
  • EP4449004B1 patent drawingFigure 2~3
  • EP4449004B1 patent drawingFigure 4~5

AI summary

The invention relates to a fluid transport pipe (2) comprising a steel tube (4) intended to receive a flow of fluids to be transported, and an annular lining (6) which is intended for protecting against corrosion and/or abrasion, is made of polymeric material and is inserted into the tube, the lining comprising a plurality of slots (8-1) which extend lengthwise in parallel with a longitudinal axis (X-X) of the tube and which pass all the way from an inner face to an outer face of the lining, each slot being open on the side of the inner face of the lining prior to the insertion of the lining into the tube, and at least partially closed depthwise between the inner face and the outer face of the lining once the lining has been inserted into the tube.