Pipeline Field Joint Coating Blend to Prevent Cracking

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Solution Overview

Problem

Existing pipeline field joint coatings, particularly those using polyurethane materials, face issues with cracking due to internal stresses and differential expansion between insulation and steel equipment, and there is a need for improved adhesive layers to enhance bond strength between conventional polypropylene pipe coatings and non-PP field joint coatings to prevent corrosion.

Innovation Solution

A method involving the application of a coating material composition comprising a propylene polymer and a substantially linear ethylene copolymer or linear ethylene copolymer to the uncoated region of pipeline field joints, which overlaps with and extends between the polypropylene pipe coatings, using injection molding techniques to create a robust and compatible barrier against moisture and contaminants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If polyurethane material is used for field joint coating, then the coating process is simplified with shorter curing time, but cracking occurs due to internal stresses and differential expansion

Engineering Contradiction:

Improvecoating cycle timeVSAvoidcracking resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the material composition parameters by using a propylene polymer blend with specific ethylene copolymer content (5-50 weight percent) and controlled molecular weight distribution. This parameter optimization reduces internal stresses and differential expansion, preventing cracking while maintaining the efficiency of the polyurethane coating process

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite coating material by blending propylene polymer with ethylene copolymer and optionally impact modifiers. This composite structure combines the advantages of both polymers: the corrosion resistance of propylene with the flexibility and stress-absorption capabilities of ethylene copolymer, eliminating cracking while maintaining fast curing

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional adhesive layers are used between polypropylene pipe coating and non-PP field joint coating, then the bonding is sufficient for basic application, but bond strength is reduced due to chemically dissimilar materials

Engineering Contradiction:

Improvecoating application simplicityVSAvoidbond strength between coatings

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent introduces an intermediary adhesive layer comprising polypropylene and ethylene copolymer that chemically bridges the dissimilar materials. This intermediary layer contains functional groups that can bond with both the polypropylene pipe coating and the non-PP field joint coating, significantly enhancing interfacial adhesion strength

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent optimizes the adhesive layer composition parameters, specifically the ratio of polypropylene to ethylene copolymer (95:5 to 50:50 by weight), and controls the layer thickness (0.1-5 mm). These parameter adjustments maximize the chemical compatibility and bonding strength between dissimilar coating materials

Inventive Principle:

Principle #35Parameter changes

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 reduces internal stresses and cracking in the insulation, enhances bond strength between the pipe and field joint coatings, and provides a durable barrier against corrosion, improving the overall integrity and longevity of the pipeline.

Implementation Method 1

using injection molding techniques to create a robust and compatible barrier against moisture and contaminants

Methodology Applied

Scientific EffectInjection molding:

Implementation Method 2

The solution reduces internal stresses and cracking in the insulation

Methodology Applied

Scientific EffectStress reduction through polymer blending:

Implementation Method 3

cracking due to internal stresses and differential expansion between insulation and steel equipment

Methodology Applied

Scientific EffectDifferential expansion: Thermal Expansion

Implementation Method 4

enhances bond strength between the pipe and field joint coatings to prevent corrosion

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 5

provides a durable barrier against corrosion, improving the overall integrity and longevity of the pipeline

Methodology Applied

Scientific EffectCorrosion protection:

Data Source

PatentUS11174410B2Method for coating a pipeline field joint

Publication Date: 2021.11.16 DOW GLOBAL TECHNOLOGIES LLC

AI summary

The present invention relates to a method of coating a pipeline field joint comprising the steps of (a) applying a layer of a coating material composition comprising (i) a propylene polymer and (ii) a substantially linear ethylene copolymer, a linear ethylene copolymer, or mixtures thereof, to the uncoated region of the field joint, preferably the coating is applied by injection molding.