Analysis of Alternatives
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ANALYSIS OF ALTERNATIVES Legal name of applicants: Wesco Aircraft EMEA Limited Cytec Engineered Materials Ltd. OR PPG Central (UK) Ltd. in its legal capacity as Only Representative of PRC DeSoto International Inc. – OR5 Submitted by: Wesco Aircraft EMEA Limited. Substance: Strontium chromate; EC No: 232-142-6; CAS: 7789-06-2 Use title: Use of strontium chromate in primers applied by aerospace and defence companies and their associated supply chains. Use number: 1 Disclaimer This document shall not be construed as expressly or implicitly granting a license or any rights to use related to any content or information contained therein. In no event shall applicant be liable in this respect for any damage arising out or in connection with access, use of any content or information contained therein despite the lack of approval to do so. ii Copy right protected - Property of Members of the GCCA Consortium - No copying / use allowed. CONTENTS 1. OPENING REMARKS 1 Introduction 1 2. INTRODUCTION 10 2.1. Substance 10 2.2. Uses of strontium chromate 10 2.3. Purpose and benefits of Cr(VI) compounds 11 3. ANALYSIS OF SUBSTANCE FUNCTION 12 3.1. Functional overview 12 3.2. Surface treatment process 19 3.3. Primer Categories 21 3.3.1 Primers 21 3.4. Strontium chromate – substance specific characteristics 23 3.4.1 Key physical-chemical quality parameters for corrosion inhibitors 23 3.4.2 Physical-chemical characteristics and properties of strontium chromate 23 3.5 Key chromate functionalities 24 3.6 Key technical criteria 25 4 ANNUAL TONNAGE 28 4.1 Annual tonnage band of strontium chromate 28 5 GENERAL OVERVIEW ON THE SPECIFIC APPROVAL PROCESS IN THE AEROSPACE INDUSTRY 29 5.1 General overview 29 5.2 Development, qualification and validation 33 5.2.1 Requirements development 34 5.2.2 Formulation development 35 5.2.3 Technology development 35 5.2.4 Qualification and Validation 36 5.3 Certification 37 5.4 Implementation / industrialisation 39 5.5 Implementation at customers and maintenance, repair and operations (MROs) 40 6 IDENTIFICATION OF POSSIBLE ALTERNATIVES 42 6.1 Description of efforts made to identify possible alternatives 42 6.1.1 Research and development 42 6.1.2 Data searches 50 6.1.3 Consultations 50 6.2 List of candidate alternatives 50 7 SUITABILITY AND AVAILABILITY OF CANDIDATE ALTERNATIVES 52 7.1 Classical corrosion inhibitors based on phosphate, silicate, pH-buffering additives 52 7.1.1 Substance ID and properties 52 7.1.2 Technical feasibility 53 7.1.3 Economic feasibility 53 7.1.4 Reduction of overall risk due to transition to the alternative 53 7.1.5 Availability 53 7.1.6 Conclusion on suitability and availability for Classical corrosion inhibitors based on phosphate, silicate, pH-buffering additives 53 7.2 Molybdate-based corrosion inhibitors 54 7.2.1 Substance ID and properties 54 7.2.2 Technical feasibility 54 7.2.3 Economic feasibility 54 7.2.4 Availability 54 7.2.5 Reduction of overall risk due to transition to the alternative 54 7.2.6 Conclusion on suitability and availability for molybdate-based corrosion inhibitors 54 7.3 Rare earth-based corrosion inhibitors (praseodymium (Pr)) 55 7.3.1 Substance ID and properties 55 7.3.2 Technical feasibility 55 iii Copy right protected - Property of Members of the GCCA Consortium - No copying / use allowed. 7.3.3 Economic feasibility 55 7.3.4 Reduction of overall risk due to transition to the alternative 55 7.3.5 Availability 55 7.3.6 Conclusion on suitability and availability of RE-based corrosion inhibitors 55 7.4 Rare earth, enhanced corrosion inhibitors (Rare Earth complexes combined with molybdate or tungstate corrosion inhibitors)) 56 7.4.1 Substance ID and properties 56 7.4.2 Technical feasibility 56 7.4.3 Economic feasibility 56 7.4.4 Reduction of overall risk due to transition to the alternative 56 7.4.5 Availability 56 7.4.6 Conclusion on suitability and availability of RE-based corrosion inhibitors 57 7.5 Sacrificial metal-based corrosion inhibitors 57 7.5.1 Substance ID and properties 57 7.5.2 Technical feasibility 57 7.5.3 Economic feasibility 57 7.5.4 Reduction of overall risk due to transition to the alternative 57 7.5.5 Availability 57 7.5.6 Conclusion on suitability and availability for sacrificial metal -based corrosion inhibitors 57 7.6 Zinc-based corrosion inhibitors 58 7.6.1 Substance ID and properties 58 7.6.2 Technical feasibility 58 7.6.3 Economic feasibility 58 7.6.4 Reduction of overall risk due to transition to the alternative 58 7.6.5 Availability 58 7.6.6 Conclusion on suitability and availability for zinc-based corrosion inhibitors 59 8 OVERALL CONCLUSIONS ON SUITABILITYAND AVAILABILITY OF POSSIBLE ALTERNATIVES FOR STRONTIUM CHROMATE 60 9 REFERENCES 64 APPENDIXES 66 APPENDIX 1 – INFORMATION ON PROPERTIES AND HAZARD CLASSIFICATION AND LABELLING OF POSSIBLE ALTERNATIVES 67 APPENDIX 1.1: Classical corrosion inhibitors – Phosphate-based corrosion inhibitors 67 APPENDIX 1.2: Classical corrosion inhibitors – Silicate-based corrosion inhibitors 69 APPENDIX 1.3: Classical corrosion inhibitors – pH buffering additives 70 APPENDIX 1.4: Molybdate-based corrosion inhibitors 72 APPENDIX 1.5: Rare Earth-based corrosion inhibitors 73 APPENDIX 1.6: Rare Earth, enhanced corrosion inhibitors 74 APPENDIX 1.7: Sacrificial metal-based corrosion inhibitors 76 APPENDIX 1.8: Zinc-based corrosion inhibitors 78 iv Copy right protected - Property of Members of the GCCA Consortium - No copying / use allowed. List of Figures: Figure 1: Example of Surface Treatment layers 3 Figure 2: Development of corrosion-prevention coating systems, from past to future (AMMTIAC, 2012, amended) 4 Figure 3: Illustration of the development, qualification, validation, certification and industrialisation process required in the aerospace industry 6 Figure 4: ATR 600 aircraft & Gulfstream V aircraft (UTC Aerospace Systems – Propeller Systems, 2014) 15 Figure 5: BAE Systems, 2017 16 Figure 6: Missiles and launchers on the F-16 and air transportable radar (U.S. Department of Defense, Photo Gallery) 16 Figure 7: Propellers mounted on an aircraft. (UTC Aerospace Systems – Propeller Systems, 2014) 16 Figure 8: Landing gear (The General Electric Company, 2015) 17 Figure 9: Left: CF6 Aircraft Engine. Right: Technology from the CF6 engine in generating power for the world’s largest hospital. (The General Electric Company, 2014) 17 Figure 10: Gas Turbine Engine sketch example PW4000 92 inch fan engine (www.pw.utc.com/Content/PW400094_Engine/img/B-1-4-1_pw400094_cutaway_high.jpg, 2014). 17 Figure 11: Cross sections of a representative aircraft engine and corresponding aeroderivative gas turbine showing location of common chrome treated parts (General Electric, 2015) 18 Figure 12: Close up examples of common treated assemblies and parts (shaft, blades and case) (General Electric, 2015) 18 Figure 13: Emergency door damper for a civil aircraft. (UTC Aerospace Systems – Propeller Systems, 2014) 18 Figure 14: Partially assembled main helicopter rotor. (UTC Aerospace Systems – Propeller Systems, 2014) 19 Figure 15: Surface Treatment Processes steps covered in this AoA 19 Figure 16: Surface Treatment layers 20 Figure 17: Development of coating systems – from the past to the future (AMMTIAC 2012, amended) 21 Figure 18: Bonding primer applied on the propeller tulip in green (left) which contributes to the bonding performance between the tulip and the composite blade (right). (UTC Aerospace Systems – Propeller Systems, 2014). 22 Figure 19: Active corrosion inhibitors (General Electric, 2013) 24 Figure 20: Illustration of the qualification, certification and industrialisation processes. 31 Figure 21: Key phases of introducing a candidate alternative into production hardware. 32 Figure 22: Illustration of the technology development and qualification process. (EASA, 2014; amended) 34 Figure 23: Typical phases of technology development within the Aerospace industry (Rolls Royce, 2016). 42 Figure 24: Schematic representation of screening process for Candidate Alternatives (A through H) with respect to design parameters and TRL level. 44 v Copy right protected - Property of Members of the GCCA Consortium - No copying / use allowed. List of Tables Table 1: Overview of key requirements for corrosion-resistant coatings 3 Table 2: Overview of key potential alternatives for corrosion-resistant coatings 5 Table 3: Substances included in this analysis of alternatives. 10 Table 4: Examples of corrosion prone areas where strontium chromate primers are applied. 12 Table 5: Non-exhaustive overview of common primer surface treatment processes. 23 Table 6: Strontium Chromate chemical and physical properties. 23 Table 7: Technology Readiness Levels – Overview (US Department of Defence, 2011, adapted 2014). 31 Table 8: List of candidate alternative corrosion inhibitors and results. 50 Table 9: Non exhaustive list of other emerging or experimental potential/candidate primer alternatives. 51 Table 10: Overview of key requirements for corrosion-resistant coatings 60 Table 11: Overview of key potential alternatives for corrosion-resistant coatings 61 vi Copy right protected - Property of Members of the GCCA Consortium - No copying / use allowed. Abbreviations AA2024 Aluminium alloy, most commonly used in the aerospace industry ACE Aerospace Chrome Elimination Acute Tox. Acute Toxicity AfA Application for Authorisation AMMTIAC Advanced Materials, Manufacturing, and Testing Information Analysis Center AMSCA Accelerated Manufacturing with Chrome Free Sacrificial Cermet Coatings in Aerospace AoA Analysis of Alternatives app. Approximately Asp.