Handbook and damage atlas for

inspection of glass fiber reinforced

plastics

Polymeric researcher, Swerea KIMAB

Klas.esbo@swerea.se

Klas Esbo

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KIMAB Swerea KIMAB is one of the oldest Swedish research institute- founded

1921 and it is a merge between the corrosion institute and the institute for

metal research

Gunnar Bergman started year 1981 the polymer group

Polymeric Materials

Chemical industry

Paper and Pulp

Plastic Joining Nuclear power

Steel industry

Pickling

Water and

waste water

Chlor/Alkali

Desinfection

Relining

Flue gas

cleaning

4

Karin

Jacobson

Group Leader

Polymeric Materials

Daniel

Ejdeholm

Research Leader

e

Martina Källrot

Janstål

Researcher

Love

Pallonen

Researcher

Dinko

Lukes

Researcher

4

Nina Pendergraph

Researcher

Kenny Constanzo

Researcher

Klas Esbo

Researcher

Agenda

• Introduction

-Thermosetting resin

-Glass fiber

• Failures and damages

-Common failures

• Inspection

-Destructive

-Non destructive

• Conclusion

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Introduction

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Polymer

Glass fibers

Glass fiber reinforced

plastic (FRP)

Introduction

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Thermosetting Resin

Glass fibers

Glass fiber reinforced

plastic (FRP or GRP)

Different types

Polymer

Initiator

Different structures

Different termosetting resin

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Thermosetting Resin

Vinyl ester

Bisphenol-A

fumarate

Terephthalic

polyester

Isophthalic

polyester Chlorendic

polyester

Different initiator for thermosetting resins

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Thermosetting Resin

Methyl Ethyl

Ketone Peroxide

(MEKP)

Cumene

Hydroperoxide

(CHP)

Benzoyl

Peroxide (BPO)

Different additives for thermosetting resins

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Thermosetting Resin

Inhibitors

Accelerators

Fillers and

Pigments

Other additives

Different glass fibers and structures

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Glass fiber

structure

Chopped strand

mat (CSM)

Woven Roving

3D-woven

Surface veil

Roving

Glass fiber

E-

Glass

C-Glass

ECR-Glass

A-Glass

Structural laminate, designed according to actual mechanical stresses.

Corrosion barrier, normally 2.5 mm thick. Protects the structural laminate from chemical attack.

Hand laid-up laminate

Structural laminate, alternating layers of woven roving (WR) and mats of chopped strand mat (CSM)

Corrosion barrier

Fibre-wound laminate Structural laminate, filament-wound with high fibre content

Corrosion barrier

Laminate build up for chemical environments

Regulations and standards

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• Regulations and standards verify that the level of quality inherent in the

specifications is, in fact, delivered to the purchaser

• Important regulations for Sweden are pressure equipment directive

(PED), AFS 2016:1 (AFS Arbetsmiljöverkets författningssamling) and

MSBs (Myndigheten för sammhällsskydd och beredskap) regulations

for tanks and pipelines

• Important standards for Sweden are EN 13121 (Behållare för kärl I

glasfiberaremerad plast för användning ovan jord), “PRN,

Plaströrsleningsnormer” and “PLN, plastkärlsnormer”

Design of GRP/FRP

ASME Boiler and Pressure Vessel Code (BPVC)

Part B - Nonferrous Material Specifications

Supplementary part to other sections of the Code providing material

specifications for nonferrous materials

European norm EN 13121 parts 1-4

GRP tanks and vessels for use above ground

Part 1: Raw materials – Specification conditions and acceptance

conditions

Part 2: Chemical resistance

Part 3: Design and workmanship

Part 4: Delivery, installation and maintenance

Failures

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Diffusion

• Polymers are permeable

• Diffusion of the media into the corrosion barrier is okay, but never

into the structural layer.

• Called weeping if it comes out through the FRP

• Microscope is the best inspection tool:

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HCl diffusion Corrosion barrier

Structural layer

Blisters

• Due to diffusions blisters are created by an osmotic process

• In general they are rather shallow and are situated close to the

surface under the corrosion barrier

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Delamination

• When different glass fiber sheets disconnect

• Could be due to heat changes

• In general more severe and lies deeper then blisters

• Can often be repaired or changed

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Discoloration

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• Can be caused by many different reasons; temperature, chemicals,

Impact damage

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• Hard and sudden damage against the laminate

• In general rather shallow but could cause severe damage on the

inside

• Outside looks like round mark with scars

Inside looks like a star

Stress corrosion cracking

• Tensile stresses together with certain chemicals cause stress

corrosion cracking

• The fibers reacts with the chemicals and can cause rapid raptures

• Extremely sensitive to impact damages

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All types of corrosion found in metals can also be found in plastics and rubber.

Uniform corrosion, wall thinning Stress corrosion Atmospheric corrosion, chalking Localized corrosion/pitting/crevice

corrosion Erosion corrosion Galvanic corrosion Filiform corrosion

Cracks

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• Surface cracks

• Drying cracks

• Structural cracks

Inspections

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Destructive testing

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Composition

Thermal history by

differential scanning

calometry (DSC)

Microscope

Chemical composition

by Fourier Transform

Infrared Spectroscopy

(FTIR)

Mechanical

strength

Non-destructive testing

• Visual inspection

• Ultrasound

• X-ray

• Acoustic emission

• Barcol Hardness

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Calculations

• The vast variations of GAP and failures makes it difficult to make

calculations

• Weakest link?

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Example

• Clear damages was noted during inspection and a represented piece

was cut out

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Possible to cut

out and repair?

Corrosion and cracks?

Change in

mechanical strength?

50% reduction!

Example The Skoghall plant had problems with leaking

joints on their Anolyte line made of Alpolite (Viapal)

Potential service life of

20 years.

Poor joints reduced the

lifetime by a factor of 2.

Conclusions

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Conclusions

• GRPs have a complex structure

• Many different failures and damages can occur. They are not always

dangerous.

• Inspections are very important. Damages can be hard to detect

• Calculations are difficult

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Scientific Work for Industrial Use

www.swerea.se