Plastics and elastomers in corrosive environments Dr Karin Jacobson

Transcription

1 Plastics and elastomers in corrosive environments Dr Karin Jacobson Research Leader Polymeric Materials Swerea KIMAB AB,

2 Swerea = Swedish research Collection 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

3 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 (H 2 SO 4, HF, ClO 2, spent acid, chlorine.)

4 Storage tanks for hydrochloric acid made of FRP (fiber reinforced ester plastic) Service life?

5 08/08/2014

6 08/08/2014

7 08/08/2014 Stress corrosion failure in FRP lined with PVDF

8 600 m 3 hot pulp

9 08/08/2014 Filament-wound fiber

10 5 years in service, Brine with Cl 2 08/08/2014

11 Diffusion Major problem, especially for fluoroplastics Lack of data Sorption/desorption often tedious and timeconsuming if at all applicable Developing quick and easy to use techniques to generate data 08/08/2014

12 Indicator technique for measuring diffusion 2 cm Pieces cut from material to be studied Exposed in selected media at chosen temperature Thin film cut from crosssection Films exposed in suitable indicator solution 08/08/2014

13 x x t = 2D t = time of immersion in acid (here 24 hours) 08/08/2014

14 x t = 2D Dx t = 2D The Einstein equation 08/08/2014

15 Diffusion coefficients in PVDF at 80 C ClO HCl HNO HBr H 2 SO Pure water is the fastest Increasing diffusion rate 08/08/2014

16 Sample from the rubber lining, liquid phase 3.1 mm 1.3 mm 0.3 mm 08/08/2014

17 An indicator technique was used to visualise the diffusion front Butyl rubber NR 08/08/2014

18 08/08/2014 This image cannot currently be displayed.

19 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

20 08/08/2014 Chemical resistance data

21 90 C moist Cl 2 from the cells 08/08/2014

22 Corrosion rate = 0.3 mm/ year Diffusion rate = 1.3 mm/ year 08/08/2014

23 Pickling in mixed acid 20% HNO 3, 4% HF ca 65 C 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 08/08/2014

24 08/08/2014 Crack propagation in polyethylene

25 Problem with weldability during repair work Tried to weld here but failed. More material had to be removed. 08/08/2014

26 About mm The wall thickness is 40 mm 08/08/2014

27 08/08/2014 Leaking welds that could not be repaired

28 08/08/2014

29 08/08/2014 A decision is made to not use PP i HCl environments

30 08/08/2014 Influence of processing technique on material performance

31 Corrosion in mixed acid (HF and HNO 3 ) The two parts are from different producers 08/08/2014 The plant has now stopped buying from the supplier of the flange due to this problem

32 Injection moulded parts Extruded pipe 08/08/2014 All parts from the same supplier

33 Microscope with polarised light to study crystal structure 100 µm Injection moulded bend 08/08/2014 Extruded pipe

34 Sorption and desorption Viton rubber before and after exposure at a paper mill

35 Cracked surface of an FRPchimney

36 08/08/2014 Absorption and desorption of water

37 Problems due to thermal elongation/contraction A leak in a PP pipe with external reinforcement of FRP for 90 C NaOH 08/08/2014

38 Institut de la Corrosion S:t Etienne Experts on testing in H 2 S

39 This image cannot currently be displayed. Polymeric materials in nuclear- and water power plants Assessing the status of polymeric materials in our nuclear and water power plants

40 Study of polymeric materials in concrete constructions 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

41 Recycling Tunnel kiln lime in EPDM Major bi-product from steel production Similar properties to CaCO 3 Performing ageing study Co-operation between Swerea, Höganäs and Gislaved

42 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.

43 Thank you!