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Handbook and damage atlas for
inspection of glass fiber reinforced
plastics
Polymeric researcher, Swerea KIMAB
Klas Esbo
1
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
5
Introduction
6
Polymer
Glass fibers
Glass fiber reinforced
plastic (FRP)
Introduction
7
Thermosetting Resin
Glass fibers
Glass fiber reinforced
plastic (FRP or GRP)
Different types
Polymer
Initiator
Different structures
Different termosetting resin
8
Thermosetting Resin
Vinyl ester
Bisphenol-A
fumarate
Terephthalic
polyester
Isophthalic
polyester Chlorendic
polyester
Different initiator for thermosetting resins
9
Thermosetting Resin
Methyl Ethyl
Ketone Peroxide
(MEKP)
Cumene
Hydroperoxide
(CHP)
Benzoyl
Peroxide (BPO)
Different additives for thermosetting resins
10
Thermosetting Resin
Inhibitors
Accelerators
Fillers and
Pigments
Other additives
Different glass fibers and structures
11
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
13
• 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
15
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:
16
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
17
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
18
Discoloration
19
• Can be caused by many different reasons; temperature, chemicals,
Impact damage
20
• 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
21
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
23
• Surface cracks
• Drying cracks
• Structural cracks
Inspections
24
Destructive testing
25
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
26
Calculations
• The vast variations of GAP and failures makes it difficult to make
calculations
• Weakest link?
27
Example
• Clear damages was noted during inspection and a represented piece
was cut out
28
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
30
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
31
32
Scientific Work for Industrial Use
www.swerea.se