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1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2008 SAE International All rights reserved. No part of this publication m
3、ay be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org AIR3270 AEROSPACE INFORMATION REPORT Issued 2008-01 Aircraft Sealant Removal Techniques RATIONALE This Aerospace Information Report is being created to provide information on the possible methods of sealant removal.
5、INTRODUCTION The goal of this Aerospace Information Report entitled “Aircraft Sealant Removal Techniques” is to provide information on the possible methods of sealant removal. The report will compare methods and give the strengths and weaknesses of each method. Finally, there is an analysis chart to
6、 help the user determine the best method for their application. FOREWORD Some of the information in this report was taken from a previous AFRL aircraft coating removal study performed by the University of Dayton Research Institute (UDRI)1 as well as other deseal/reseal programs including F-111, B-1,
7、 Joint STARS, KC-10, KC-135. TABLE OF CONTENTS 1. SCOPE3 1.1 Purpose.3 1.2 Field of Application3 2. APPLICABLE DOCUMENTS3 2.1 UDRI Reports3 3. BACKGROUND DISCUSSION.3 4. REMOVAL METHODS .4 4.1 Chemical Stripping4 4.1.1 Soy Strip, Franmar5 4.1.2 Skywash/Skyrestore, Elixair.5 4.1.3 Acrastrip 600 BG MO
8、D, Polychem .5 4.1.4 Poly-Gone 535, RPM Technology 5 4.2 Biological Degradation6 4.3 Mechanical Stripping.7 4.3.1 Dry Abrasive Blasting8 4.3.2 Wet Abrasive Blasting.9 4.3.3 Water Jet Blasting.10 4.3.4 Cold Media Blasting11 4.3.5 Ultrasonic Activated Tools 12 4.3.6 Rotary Power Tools 13 4.3.7 Pneumat
9、ic Vibrating Scrapers 14 1 AFRL Contract F33615-95-D-5516, UDRI Study “Rapid Removal of Radar Absorbing Coatings”, UDR-TR-2000-00031, February 2000. Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 02/16/2008 01:38:
10、00 MSTNo reproduction or networking permitted without license from IHS -,-,- SAE AIR3270 - 2 - 4.4 Thermal Stripping15 4.4.1 Laser Sealant Removal.15 4.4.2 Flash Lamp Stripping16 5. RATING AND RANKING SEALANT REMOVAL PROCESSES FOR APPLICABILITY.18 6. CONCLUSIONS/RECOMMENDATIONS.19 7. JUSTIFICATION .
11、19 APPENDIX A RATING/RANKING OF PROCESSES FOR FIELD LEVEL APPLICATION 20 APPENDIX B REMOVAL METHOD COSTS AND COMMERCIAL AVAILABILITY .21 FIGURE 1 COMMONLY APPROVED HAND TOOLS.7 FIGURE 2 PAULI SYSTEMS RAM 45 VCC PORTABLE WET ABRASIVE SYSTEM9 FIGURE 3 AERO 30 COLD MEDIA BLAST SYSTEM FROM COLD JET.11 F
12、IGURE 4 ULTRASONIC CUTTER.12 FIGURE 5 3M FIRST GENERATION ROTARY CUTTERS AND RADIAL BRISTLE BRUSH13 FIGURE 6 OUTZONE VIBRO GUN PNEUMATIC SCRAPER 14 FIGURE 7 GENERAL LASERTRONICS END EFFECTER/ LASER SYSTEM AND CHILLER16 FIGURE 8 FLASHJETTM SYSTEM OPERATING ON AN AIRCRAFT WING17 TABLE 1 ATTRIBUTES USE
13、D IN RATING/RANKING CURRENTLY AVAILABLE SEALANT REMOVAL METHODS4 TABLE 2 SEALANT REMOVAL/CLEANING PROCESSES4 TABLE 3 PROS AND CONS OF CHEMICAL STRIPPING SEALANT REMOVAL PROCESS.6 TABLE 4 PROS AND CONS OF BIOLOGICAL DEGRADATION SEALANT REMOVAL PROCESS 6 TABLE 5 ABRASIVE MEDIA MATERIALS 7 TABLE 6 ABRA
14、SIVE BLASTING PROCESS PARAMETERS.8 TABLE 7 PROS AND CONS OF DRY ABRASIVE BLASTING.8 TABLE 8 PROS AND CONS OF WET ABRASIVE BLASTING.10 TABLE 9 PROS AND CONS OF WATER JET BLAST11 TABLE 10 PROS AND CONS OF COLD MEDIA BLASTING .12 TABLE 11 PROS AND CONS OF ULTRASONIC ACTIVATED TOOLS.13 TABLE 12 PROS AND
15、 CONS OF ROTARY POWER TOOLS14 TABLE 13 PROS AND CONS OF PNEUMATIC VIBRATING SCRAPER 15 TABLE 14 PROS AND CONS OF LASER BASED STRIPPING.16 TABLE 15 PROS AND CONS OF FLASH LAMP STRIPPING17 Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/394400
16、0013 Not for Resale, 02/16/2008 01:38:00 MSTNo reproduction or networking permitted without license from IHS -,-,- SAE AIR3270 - 3 - 1. SCOPE This SAE Aerospace Information Report (AIR) provides information on the possible methods of sealant removal. The discussion will focus on the methods of seala
17、nt removal and give the strengths and weaknesses of each method. 1.1 Purpose The purpose of this document is to assist those concerned with aircraft sealant removal to choose the best available method for their purpose considering a number of factors. Recognition of the ESOH (Environmental, Safety,
18、and Occupational Health) hazards involved in the traditional (chemical based) sealant removal processes as well as the ever increasing cost of the associated waste disposal involved, prompted the DOD to initiate a number of programs to test and evaluate alternative sealant removal processes, as well
19、 as, to develop new technology approaches. This DOD activity is also driven by the need to comply with numerous environmental regulations and statutes promulgated by the EPA (Environmental Protection Agency) initiatives to include: the Clean Water Act (CWA), Clean Air Act (CAA) amendments of 1990, t
20、he Resource Conservation and Recovery Act (RCRA) and the Occupational Safety and Health Act (OSHA). 1.2 Field of Application The field of application includes aircraft sealant removal at the manufacturing, depot, and field levels. 2. APPLICABLE DOCUMENTS Shall be in accordance with AS5502 (1.1). 2.1
21、 UDRI Reports UDR-TR-2000-00031, (February 2000) Rapid Removal of Radar Absorbing Coating. 3. BACKGROUND DISCUSSION Sealant removal technology may conveniently be separated into four rather broad categories. These are Chemical, Biological, Mechanical and Thermal. A number of the processes available
22、use a combination of the technology in these categories to ensure complete sealant removal. Traditional methods for the removal of sealants from aircraft structures and components involve the use of chemical formulations containing strong solvating chemicals such as methylene chloride (MECL) and met
23、hyl alcohol (MA) activated with strong organic acid or base materials. In most instances repeated applications of these formulations were required in order to remove multiple coats of sealant material. Scraping and/or sanding was required between applications of the strippers to remove the blistered
24、 and loosened sealant. This process involved the release of Ozone Depleting Chemicals (ODC), Volatile Organic Compounds (VOCs), Hazardous and Toxic vapors, (HAZTOX), Hazardous Air Pollutants (HAPs) as well as the production of large volumes of contaminated wastewater from the rinsing process that is
25、 required. These processes are still prevalent today but are not the only option, and likely not the best option. This AIR will introduce you to currently available sealant strip methods and help you choose the best method for your application using the following attributes listed in Table 1. Copyri
26、ght SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 02/16/2008 01:38:00 MSTNo reproduction or networking permitted without license from IHS -,-,- SAE AIR3270 - 4 - TABLE 1 - ATTRIBUTES USED IN RATING/RANKING CURRENTLY AVAILA
27、BLE SEALANT REMOVAL METHODS Process Attributes 1. ESOH (environmental/safety/occupational health) 2. Field level applicability 3. Portability/mobility/size 4. Potential for substrate damage 5. Cost to implement (equipment/training/waste disposal, etc.) 6. Process effectiveness (completeness of seala
28、nt removal) 7. Rate of sealant removal 4. REMOVAL METHODS Currently used methods for the removal of sealants from aircraft surfaces, at the field level, involve the use of hand tools (scrapers) and/or solvent base strippers. The process is very time consuming and can result in damage to the aircraft
29、 substrate material. Alternative sealant removal methods that are: safer, more environmentally friendly, faster, and lower cost can be viewed in terms of both alternative materials and alternative technologies or a combination of both. A listing of the processes presently in use or in the final stag
30、es of development is presented in Table 2. TABLE 2 - SEALANT REMOVAL/CLEANING PROCESSES Chemical Biological Mechanical Thermal Methyl Ethyl Ketone Methylene Chloride Methanol Thiolates dissolved in Dimethylformamide Sealant Removal Wipe Thixotropic Gels Soy Based Strippers Low VOC Non-Hazardous Solv
31、ents Bacillus subtilis Proteus vulgarius Pseudomonas aeruginosa Streptoverticillium reticulum Dry abrasive blasting Wet abrasive blasting Water jet blasting CO2 pellet blasting Fluidized bed stripping Ice crystal blasting Ultrasonic activated knives and scrapers Ultrasonic jet Hand tools Power Hand
32、Tools Laser Flash Lamp Molten Salt Bath Cryogenic (liquid nitrogen) 4.1 Chemical Stripping Sealant removal can be accomplished with chemical solvents that are far less hazardous than those used in traditional formulations. Such alternative stripping chemicals include SkyKleen, Elixair Skywipes, Elix
33、air Skywash, Elixair Skyrestore, Poly-Gone 535, Franmar Soystrip, Polychem Acrastrip 600BL, and Solvent Solutions 75. The process utilized with this alternative material is essentially the same as that used with the traditional formulations, such as Methyl Ethyl Ketone (MEK) shown in Table 2. The st
34、ripping solution is sprayed or otherwise applied onto the work area to soften, blister or dissolve the sealant. Some form of mechanical action including hand scraping, brushing, CO2 or water jet, etc then removes the loosened sealant. Rinsing may be required after using particular chemical sealant r
35、emovers. Heat can be used to facilitate efficient rinsing. Multiple stripper applications and sealant removal steps are required in cases where many layers of sealant are encountered. The waste produced via the chemical stripping methods may or may not be a HAZTOX material depending upon the sealant
36、 formulation and the solvent chemicals chosen. Chemical stripping is very effective on sealant coated metallic surfaces due to the existence of a high impedance coating-metal interface and is probably one of the least likely processes to cause substrate damage. This is due to the relatively low leve
37、ls of mechanical energy required to remove the softened sealant residue. Chemical stripping is not recommended for organic resin base composites (glass or carbon fiber reinforced plastics). The lack of a high impedance interface to stop the penetration of the stripper chemical allows the ready penet
38、ration into the composite substrate and the potential for substrate damage exists. The stripper cannot distinguish between the sealant and the urethane coatings and will soften the coating upon prolonged contact. Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA
39、 related to 3944000/3944000013 Not for Resale, 02/16/2008 01:38:00 MSTNo reproduction or networking permitted without license from IHS -,-,- SAE AIR3270 - 5 - Chemical stripping via the use of more environmentally friendly chemicals and water free secondary sealant removal processes may be the proce
40、ss of choice for thin metallic substrates that may be damaged by the more aggressive methods. The pros and cons of chemical stripping sealant removal methods are shown in Table 3. The two most common application techniques for chemical strippers are hand applications or mechanical applications. Most
41、 small area applications can be accomplished with hand application techniques. The most common techniques are brush or cloth wipe applications. For large area applications mechanical spray systems are most frequently used. If the system is automated it allows personnel to remain at a safe distance,
42、or in the best situations, entirely outside the room where the stripping is being performed. CAUTION: MEK, MIBK, and MIL-C-38736 are flammable and toxic to eyes, skin, and respiratory tract. Skin and eye protection are required. Avoid prolonged or repeated contact. Use adequate ventilation or respir
43、atory protection. Keep away from open flames and other sources of ignition. 4.1.1 Soy Strip, Franmar Franmar manufactures this alternative to high VOC hazardous strippers. It is part of an entire line of marine coating and paint strippers all made from 100% soybeans. Soy Gel is a potential choice to
44、 replace high VOC strippers. It contains 0% VOCs. Soy Gels thick consistency makes its application neater and easily controlled. It can be applied to the underside of a surface and will not drip off. Soy Gel was tested at the University of Dayton on coatings and polysulfides. Its removal rate was no
45、ticeably quicker than the other low VOC strippers tested. For more information from the manufacturer of these products please reference: http:/ 4.1.2 Skywash/Skyrestore, Elixair Elixairs family of environmentally friendly sealant strippers includes Elixair Skywash, Elixair Skywipes, and Elixair Skyr
46、estore. Skywash is a wipe or brush on cleaning agent. Skywipes are a lint free cloth with the stripper already impregnated, for a wipe on application. Skywipes use the Skywash stripper only in a different medium. Skyrestore is a second environmentally friendly chemical stripper, and can be applied w
47、ith a brush or wipe method. For more information from the manufacturer of these products please reference: http:/www.elixair.co.uk/full-brochure.pdf. 4.1.3 Acrastrip 600 BG MOD, Polychem Originally designed as a coating removal material, Acrastrip has proven effective in removing polysulfide sealant
48、s. According to Polychems website Acrastrip 600 B thus no abrasive media is required. At higher pressures the water jet is used to strip ceramic coatings from turbine engine components. As in the wet abrasive blast, the water jet can drive water in skin joints and fasteners causing potential for corrosion. The waste from the water jet process is sludge formed by the sealant debris and the process water. This sludge may or may not be HAZTOX, depending on the formulation of the sealant being removed. The water jet proce