Polymers in plant engineering More safety in critical applications Ansgar Holtermann; Dipl.-Ing. Röchling Engineering Plastics KG

Transcription

1 Polymers in plant engineering More safety in critical applications Ansgar Holtermann; Dipl.-Ing. Röchling Engineering Plastics KG

2 More safety in critical applications Content Definition: Critical applications for plastics in plant engineering Project example 1: Project example 2: Aggressive operating chemical Summary Seite 2

3 More safety in critical applications Content Definition: Critical applications for plastics in plant engineering Project example 1: Project example 2: Aggressive operating chemical Summary Seite 3

4 Definition: Critical applications Typical fields of application Storage tanks Material: PE 100 Medium: e.g. Sodium Hydroxide 50 % Temperature: 30 C Static design: DVS Chemical reduction factors (A 2 ): Media lists 40 of the DIBt (Deutsches Instituts für Bautechnik) No critical application! Picture: Kürner KTA GmbH, Pfohren, Germany Seite 4

5 Definition: Critical applications Typical fields of application Process tanks Material: PP-H Medium: e.g.: Hydrochloric acid 20 % Temperature: C Static design: DVS Chemical reduction factors (A 2 ): Media lists 40 of the DIBt (Deutsches Instituts für Bautechnik) No critical application! Picture: Dotmar EPP, Australia Seite 5

6 Definition: Critical applications Important factors for the suitability of thermoplastic materials Temperature Chemistry Seite 6

7 Definition: Critical applications Significant reduction of material strength and stiffness Rapid ageing of the material due to thermo oxidative degradation Use of aggressive chemicals Development of stress cracks and faster ageing of the material caused by strong oxidizing chemicals Reduction of stiffness (as a result of swelling) Many chemicals not contained in the current DIBt media lists Seite 7

8 More safety in critical applications Content Definition: Critical applications for plastics in plant engineering Project example 1: Project example 2: Aggressive operating chemical Seite 8

9 Project example 1: Pickling of steel Common processes Metal Medium Concentration Temperature Steel Sulfuric acid % C Steel Hydrochloric acid % C Picture: CMI UVK GmbH, Montabaur, Germany Seite 9

10 Project example 1: Equipment manufacturer: UVK GmbH, Montabaur End user: ThyssenKrupp Steel Europe AG, Bruckhausen Medium: Sulfuric acid (H 2 SO 4 ) 20 % Temperature: 105 C Material: PP-H Seite 10

11 Project example 1: Creep strength PP-H Ductile failure due to plastic deformation Brittle failure due to slow crack growth 105 C Brittle failure due to thermooxidative degradation Source: DVS Technical Codes on Plastics Joining Technologies Seite 11

12 Project example 1: Influence of the operating temperature on the creep strength of PP-H Earlier ageing due to thermal oxidative ageing of the material Calculated service life of the material < 5 years Requirement: Minimum service life 5 years Solution: Use of effective heat stabilizers Seite 12

13 Project example 1: Influence of the stabilizers on the creep strength of PP-H 105 C Influence of the stabilizers Seite 13

14 Project example 1: Chemical structures of the most important antioxidants BASF Seite 14

15 Project example 1: Autoxidation cycle BASF Seite 15

16 Project example 1: Requirements for the heat stabilizer Chemical resistance against the operating media Extraction stability Good compatibility with PP Seite 16

17 More safety in critical applications Content Definition: Critical applications for plastics in plant engineering Project example 1: Project example 2: Aggressive operating chemical Summary Seite 17

18 Project example 2: Aggressive operating chemical Zinc electrolysis In zinc electrolysis, zinc oxide is dissolved in sulfuric acid and zinc is deposited on the cathode. ZnO + H 2 SO 4 ---> ZnSO 4 + H 2 O Cathode equation: Zn e- ---> Zn0 Stabilizing Zn 2+ by the addition of oxidizing agents Anode equation: SO Pb ---> PbSO e- Medium Concentration Temperature Sulfuric acid ~20 % 30 C Seite 18

19 Project example 2: Aggressive operating chemical Equipment manufacturer: Steuler KCH, Höhr-Grenzhausen End user: Medium: Mefasa* S.A., Spain Sulfuric acid (H 2 SO 4 ) 20 %, further additives Temperature: 30 C Material: PE 100-RC *Mefasa: Mecanizaciones y Fabricaciones. S.A. Picture: Steuler KCH GmbH, Höhr-Grenzhausen, Germany Seite 19

20 Project example 2: Aggressive operating chemical Influence of the chemical on the service life of the material Aggressiveness of the operating chemical: In field tests showed that PP-H is not resistant against the operating chemicals. Stress cracks are developing. Oxidants used in the process accelerate the ageing of the material and lead to a reduction of the service life. Requirements on the material: 1. High stress cracking resistance 2. Resistance against oxidative chemical attack Seite 20

21 Project example 2: Aggressive operating chemical Requirement: High stress cracking resistance Solution: PE 100-RC PE h PE 100-RC 8760 h h No brittle fractures due to slow crack growth But: A high stress cracking resistance does not slow down the ageing of the material caused by the influence of the oxidants Requirements materials acc DVS Supplement 1 Seite 21

22 Project example 2: Aggressive operating chemical Requirement: Resistance against oxidative chemical attack Solution: Use of effective heat stabilizers Oxidants used in the process support the formation of radicals Use of antioxidants as radical catcher Problem solved gelöst Seite 22

23 More safety in critical applications Content Definition: Critical applications for plastics in plant engineering Project example 1: Project example 2: Aggressive operating chemical Summary Seite 23

24 More safety in critical applications Summary s in steel pickling lines can lead to an early thermal ageing of PP. By the use of effective thermal stabilizers the thermal oxidative degradation can be slowed down. Aggressive chemicals may cause stress cracking and an early ageing of the tank material. A stabilized PE 100-RC provides a high resistance against stress cracking and oxidative degradation. Seite 24

25 Many thanks for your attention! Ansgar Holtermann Röchling Engineering Plastics KG