Epoxy Thermal Insulating Coating for Corrosion Under Insulation

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Solution Overview

Problem

Existing solutions for mitigating corrosion under insulation (CUI) are ineffective, costly, and difficult to apply, particularly in critical areas, and there is a need for a composition that provides long-term protection, low thermal conductivity, enhanced corrosion resistance, and ease of application.

Innovation Solution

A composition comprising 20-60 wt.% epoxy resin, 10-30 wt.% curing agent, 1-15 wt.% glass microspheres, 10-40 wt.% corrosion-resistant fillers, 0.1-1.0 wt.% fluorine-containing dispersant, and 10-40 wt.% solvent, which is applied as a coating on metallic surfaces to mitigate CUI.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional protective coatings (organic coatings, thermal spray aluminum, Al-foil wrapping) are used for CUI mitigation, then corrosion protection is provided, but cost increases significantly and application becomes difficult in critical bent areas

Engineering Contradiction:
Improvecorrosion protectionVSAvoidapplication ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent modifies the chemical composition parameters of protective coatings by incorporating specific ratios of epoxy resin, polyester resin, vinyl acetate, and plasticizers to achieve optimal flexibility and adhesion. This allows the coating to conform to complex geometries including bent areas while maintaining corrosion protection efficacy

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses composite coating formulations combining multiple resin systems (epoxy, polyester, vinyl acetate) with specific additives and plasticizers to create a multi-functional coating that provides both corrosion protection and flexibility for difficult-to-reach areas

Inventive Principle:
Principle #40Composite materials

2Reliability

If thick insulative coatings are applied to prevent moisture ingress, then corrosion protection improves, but thermal conductivity increases and energy loss occurs

Engineering Contradiction:
Improvecorrosion protectionVSAvoidthermal energy loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent incorporates porous or hollow filler particles within the coating matrix to reduce thermal conductivity. These porous structures create air gaps that impede heat transfer while maintaining coating integrity and corrosion protection capabilities

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The coating formulation combines organic resin matrices with inorganic fillers and porous structures to create a composite material that simultaneously provides corrosion barrier properties and thermal insulation, minimizing energy loss

Inventive Principle:
Principle #40Composite materials

3Reliability

If existing CUI mitigation solutions are implemented, then some protection is achieved, but long-term effectiveness is insufficient and maintenance costs remain high

Engineering Contradiction:
Improvecorrosion protectionVSAvoidprotection duration
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies preliminary surface treatment and priming layers before the main protective coating to ensure long-term adhesion and corrosion resistance. This multi-stage approach creates a durable protective system that maintains effectiveness over extended service periods

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The use of composite coating systems with multiple resin types and cross-linking agents creates a more chemically stable and mechanically durable protective layer that resists degradation from environmental exposure, extending service life

Inventive Principle:
Principle #40Composite materials

4Reliability

If surface preparation and modification are performed to enhance coating adhesion, then corrosion protection improves, but process complexity and cost increase

Engineering Contradiction:
Improvecorrosion protectionVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The coating formulation contains self-priming components and adhesion promoters that automatically bond to metal surfaces without requiring extensive external surface preparation. The coating system performs its own surface conditioning function, simplifying the application process

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

The composition effectively mitigates CUI up to 120°C, maintains mechanical properties, reduces thermal conductivity, and is cost-effective with no pre-treatment required, offering enhanced protection and stability.

Implementation Method 1

The coating is designed for ultra-high-build (UHB) over 20000 microns (800 mils)

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

Component A primarily comprises a novolac epoxy resin, epoxy organic silicon resin, and flaky filler, whereas component B includes high functionality amine curing agent

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 3

0.1 wt.% to 1.0 wt.% of a fluorine-containing dispersant

Methodology Applied
Scientific EffectSurface tension reduction: Surfactant

Implementation Method 4

A fiber optical Doppler sensor is used for inspecting the corrosion in piping

Methodology Applied
Scientific EffectPhysical barrier: Physical Containment

Data Source

PatentEP4606858A1Development of novel and cost-effective thermal insulating coating to mitigate corrosion under insulation
Publication Date: 2025.08.27 HINDUSTAN PETROLEUM CORP LTD
  • EP4606858A1 patent drawingFigure 1~2
  • EP4606858A1 patent drawingFigure 3
  • EP4606858A1 patent drawing

AI summary

The present invention relates to a composition for mitigating corrosion under insulation, said composition comprising: (a) 20 wt.% to 60 wt.% of an epoxy resin; (b) 10 wt.% to 30 wt.% of a curing agent comprising a mixture of (b1) an aromatic compound selected from the following formula wherein, Y is an alkyl group containing 1 to 4 carbon atoms, X is hydrogen or an alkyl group containing 1 to 4 carbon atoms, and R and R', independent of each other, are selected from alkyl group containing 1 to 4 carbon atoms, and alkylthio group containing 1 to 4 carbon atoms, and (b2) an aliphatic compound; (c) 1.0 wt.% to 15 wt.% of glass microspheres; (d) 10 wt.% to 40 wt.% of corrosion resistant fillers; (e) 0.1 wt.% to 1.0 wt.% of a fluorine-containing dispersant; and (f) 10 wt.% to 40 wt.% of a solvent, wherein the wt.% is based on the total weight of the composition. The present disclosure also relates to a process for preparing the composition for mitigating corrosion under insulation.