plastics and elastomers in corrosive environments - sgf · plastics and elastomers in corrosive...
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Plastics and elastomers in corrosive environments
Dr Karin Jacobson
Research LeaderPolymeric MaterialsSwerea KIMAB AB, karin.jacobson@swerea.se
Swerea = Swedish researchCollection of Swedish material research
institutes in one group
Some of the work presented here dates back to when we were the
Swedish Corrosion Institute
Gunnar Bergman started the work on polymers corrosion in 1981
Our expertise – Need driven industrial research • Member program: Polymeric Materials in Corrosive Environments • Approximately 50 members• From producers to end users • Main focus areas are chlorine production, sulphuric acid, flue gas cleaning and
pulp and paper production• We are also active in a number of research projects and do contract work,
material recommendations, ageing studies and exposures in harsh environments (H2SO4, HF, ClO2, spent acid, chlorine….)
Storage tanks for hydrochloric acid made of FRP (fi ber reinforced ester plastic)
Service life?
08/08/2014
08/08/2014
08/08/2014
Stress corrosion failure in FRPlined with PVDF
600 m3
hot pulp
08/08/2014
Filament-wound fiber
08/08/2014
5 years in service, Brine with Cl2
Diffusion
• Major problem, especially for fluoroplastics• Lack of data• Sorption/desorption often tedious and time-
consuming if at all applicable• Developing quick and easy to use techniques to
generate data
08/08/2014
Indicator technique for measuring diffusion
08/08/2014
Pieces cut from material to be studied
Exposed inselected mediaat chosentemperature
Films exposedin suitable indicatorsolution
Thin film cutfrom cross-section
2 cm
08/08/2014
x
∆∆∆∆xt
= 2D
t = time of immersion in acid(here 24 hours)
08/08/2014
The Einstein equation
Dx
t= 2D
∆∆∆∆xt
= 2D
ClO2 2.2.10-7
HCl 2.0 .10-7
HNO3 1.2.10-7
HBr 1.4 .10-9
H2SO4 4.0.10-10
08/08/2014
Increasing diffusion rate
Pure water is the fastest
Diffusion coefficients in PVDF at 80 °C
Sample from the rubber lining, liquid phase
08/08/2014
0.3 mm
1.3 mm
3.1 mm
An indicator technique was used to visualise the diffusion front
08/08/2014
Butyl rubber
NR
08/08/2014
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Corrosion approach• Industry prefers similar approach independent of
material (steel or polymer)• Facilitates design and life-time prediction
Corroded stainless steel pipe Corroded FRP pipe
08/08/2014
Chemical resistance data
08/08/2014
90°C moist Cl 2from the cells
08/08/2014
Corrosion rate = 0.3 mm/√year
Diffusion rate = 1.3 mm/√year
08/08/2014
Chemical resistance polypropylene, S = satisfactory, L = limited, NS = not suitable
Chemical Concentration 20°C 60°C 100°C
Nitric acid Up to 30 % S NS NS
Nitric acid From 40 to 50 % L NS NS
Nitric acid Fuming NS NS NS
Pickling in mixed acid 20% HNO3, 4% HF ca 65°C
08/08/2014
Crack propagation in polyethylene
Problem with weldability during repair work
08/08/2014
Tried to weld here but failed.
More material had to be removed.
08/08/2014
About 14-15 mm
The wall thickness is 40 mm
Leaking welds that could not be repaired
08/08/2014
08/08/2014
08/08/2014
A decision is made to not use PP i HCl environments
Influence of processing technique on material performance
08/08/2014
08/08/2014
The two parts are from different producers
The plant has now stopped buying from the supplier of the flange due to this problem
Corrosion in mixed acid (HF and HNO3)
08/08/2014
Injection moulded parts
Extruded pipe
All parts from the same supplier
08/08/2014
Injection moulded bend Extruded pipe
100 µm
Microscope with polarised light to study crystal structure
Sorption and desorption
Viton rubber before and after exposure at a paper m ill
Crackedsurfaceof an FRP -chimney
08/08/2014
Absorption anddesorption of water
08/08/2014
Problems due to thermal elongation/contraction
A leak in a PP pipe with external reinforcement of FRP for 90°C NaOH
Institut de la Corrosion – S:t Etienne
Experts on testing in H2S
Polymeric materials in nuclear- and water power plants
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Assessing the status of polymeric materials in our nuclear and water power plants
� Study of polymeric materials in concrete constructi ons
� We have visited 7 of the 10 reactors in Sweden
� Forsmark 2
� Oskarshamn 1, 2 och 3
� Ringhals 1, 2 och 3
� Identifying polymeric materials with need for further investigations
� Investigating the knowledge about polymeric materials
� Identifying differences between different plants
� Main focus 2014 on elastic seals and PVC strips
RecyclingTunnel kiln lime in EPDM
• Major bi-product from steel production• Similar properties to CaCO3
• Performing ageing study
Co-operation between Swerea,Höganäs and Gislaved
Concluding remarks• Lack of relevant data and standardised material often
makes the use of polymeric materials in harsh environments to be full scale experiments
• The corrosion approach helps the end users to predict service life of their equipment
• Our research focuses on the generation of relevant data so that we can help the end users with material choices, status determinations and failure analyses.
Thank you!
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