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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2017 SAE International All rights reserved. No part of this p
3、ublication may 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: +1 724-776-4970
4、 (outside USA)Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/AMS7258B AEROSPACEMATERIAL SPECIFICATIONAMS7258 REV. B Issued 1985-07 Revised 1990-10 Reaffirmed
5、2017-11 Superseding AMS7258A Rings, Sealing, Butadiene-Acrylonitrile (NBR) Rubber Fuel Resistant, Low Shrinkage 65 - 75 RATIONALE AMS7258B has been reaffirmed to comply with the SAE Five-Year Review policy. 1. SCOPE:1.1 Form: This specification covers butadiene acrylonitrile (NBR) rubber in the form
6、 of molded rings.1.2 Application: Primarily for use in aircraft fuel systems operating from -55to+125 C (-67 to +257 F). These rings contain less plasticizer than normally used in aircraft fuel seals; therefore, there is less shrinkage when the rings are dried out. 1.3 Safety-Hazardous Materials: Wh
7、ile the materials, methods, applications, and processes described or referenced in this specification may involve the use of hazardous materials, this specification does not address the hazards which may be involved in such use. It is the sole responsibility of the user to ensure familiarity with th
8、e safe and proper use of any hazardous materials and to take necessary precautionary measures to ensure the health and safety of all personnel involved. 2. APPLICABLE DOCUMENTS:The following publications form a part of this specification to the extent specified herein. The latestissue of SAE publica
9、tions shall apply. The applicable issue of other publications shall be the issue ineffect on the date of the purchase order.2.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.2.1.1 Aerospace Material Specifications: AMS 2817 Packaging and Identification, Pref
10、ormed PackingsAMS 3022 Reference Fluid for Testing Hydrocarbon Fuel Resistant Materials, 10% Aromatic ContentAMS 4027 Aluminum Alloy Sheet and Plate, 1.0Mg - 0.60Si - 0.28Cu - 0.20Cr, (6061; -T6 Sheet, -T651 Plate), Solution and Precipitation Heat TreatedAMS 4037 Aluminum Alloy Sheet and Plate, 4.4C
11、u - 1.5Mg - 0.60Mn, (2024; -T3 Flat Sheet, -T351 Plate), Solution Heat TreatedAMS 4045 Aluminum Alloy Sheet and Plate, 5.6Zn - 2.5Mg - 1.6Cu - 0.23Cr (7075; -T6 Sheet, -T651 Plate), Solution and Precipitation Heat TreatedAMS 5513 Steel Sheet, Strip, and Plate, Corrosion Resistant, 19Cr - 9.2Ni (SAE
12、30304), Solution Heat TreatedAMS 5630 Steel Bars and Forgings, Corrosion Resistant, 17Cr - 0.52Mo (0.95 - 1.20C) (SAE 51440C)AMS 6350 Steel Sheet, Strip, and Plate, 0.95Cr - 0.20Mo (0.28 - 0.33C) (SAE 4130)2.1.2 Aerospace Standards: AS568 Aerospace Size Standard for O-ringsAS871 Manufacturing and In
13、spection Standards for Preformed Packings (O-rings)2.1.3 Aerospace Information Reports: AIR851 O-ring Tension Testing Calculations2.2 ASTM Publications: Available from ASTM, 1916 Race Street, Philadelphia, PA 19103-1187.ASTM D 1414 Testing Rubber O-ringsASTM D 2240 Rubber Property - Durometer Hardne
14、ss2.3 U.S. Government Publications: Available from Standardization Documents Order Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.2.3.1 Federal Specifications: QQ-A-250/4 Aluminum Alloy 2024, Plate and SheetQQ-A-250/11 Aluminum Alloy 6061, Plate and SheetQQ-A-250/12 Aluminum Allo
15、y 7075, Plate and SheetSAE INTERNATIONAL AMS7258B Page 2 of 12_ 2.3.2 Military Specifications: MIL-H-6083 Hydraulic Fluid, Petroleum Base, for Preservation and OperationMIL-S-18729 Steel Plate, Sheet, and Strip, Alloy 4130, Aircraft Quality2.3.3 Military Standards: MIL-STD-105 Sampling Procedures an
16、d Tables for Inspection by AttributesMIL-STD-413 Visual Inspection Guide for Elastometric O-Rings2.4 ANSI Publications: Available from American National Standards Institute, 1430 Broadway, New York, NY 10018.ANSI B46.1 Surface Texture (Surface Roughness, Waviness, and Lay)3. TECHNICAL REQUIREMENTS:
17、3.1 Material: Shall be a compound, based on a butadiene acrylonitrile (NBR) elastomer, suitably cured to produce sealing rings meeting the requirements of 3.2.3.2 Properties: Rings shall conform to the following requirements; except as otherwise specified herein, tests shall be performed in accordan
18、ce with ASTM D 1414, insofar as practicable. Calculations of tensile strength and elongation may be made in accordance with AIR851.TABLE 13.2.1 As Received:3.2.1.1 Specific Gravity Preproduction Value 0.023.2.1.2 Hardness, Durometer “A”or equivalent 70 5ASTM D 22403.2.1.3 Tensile Strength, minimum 1
19、200 psi(8.27 MPa)3.2.1.4 Elongation, minimum 200%3.2.1.5 Corrosion and Adhesion Slight corrosionallowed on 4130 steel,none on other metals4.5.1SAE INTERNATIONAL AMS7258B Page 3 of 12_ 3.2.2 Room-Temperature Fuel Resistance: Medium: ASTM ReferenceFuel B3.2.2.1 Volume Change +25 to +50% Temperature: 2
20、5 C 1(77 F 2)Time: 70 hours 0.53.2.3 Elevated-Temperature Fuel Resistance: 4.5.2Medium: AMS 30223.2.3.1 Hardness Change, Durometer “A”or equivalent -15 to 0Temperature: 125 C 3(257 F 5)Time: 70 hours 0.53.2.3.2 Tensile Strength Change, maximum -50%3.2.3.3 Elongation Change, maximum -40%3.2.3.4 Volum
21、e Change +15 to +40%3.2.4 Aliphatic Fuel Soak and Dry-out: 4.5.3Medium: ASTM Reference3.2.4.1 Volume Shrinkage,maximum 1.0%ReferenceFluid A3.2.5 Aromatic Fuel Soakand Dry-out:4.5.3Medium: ASTM ReferenceFluid B3.2.5.1 Volume Shrinkage,maximum 1.0%3.2.6 Compression Set:Percent of OriginalDeflection, m
22、aximum 60%Temperature: 125 C 3(257 F 5)Time: 70 hours 0.53.2.7 Low-TemperatureResistanceTemperature Retraction,TR10 point, maximum3.2.7.1 As Received -40 C (-40 F)3.2.7.2 After Aging70 hours 0.5 at25 C (77 F)in AMS 3022 -60 C (-76 F)TABLE 1 (Continued)SAE INTERNATIONAL AMS7258B Page 4 of 12_ 3.3 Qua
23、lity: Rings, as received by purchaser, shall be uniform in quality and condition, smooth, as free from foreign materials as commercially practicable, and free from internal imperfections detrimental to their performance. Surface imperfections shall be no greater than permitted by MIL-STD-413.3.4 Siz
24、es and Tolerances: Shall be as specified on the drawing. Inspection for conformance to dimensional requirements shall be made in accordance with AS871. Standard sizes are as shown in AS568.3.5 Part Numbers: Part numbers shall consist of the following:1. The specification identifier.2. A dash followe
25、d by the appropriate dash number from AS568.Example 1 Example 2AMS 7258-118 AMS 7258-4274. QUALITY ASSURANCE PROVISIONS: 4.1 Responsibility for Inspection: The vendor of rings shall supply all samples for vendors tests and shall be responsible for performing all required tests. Purchaser reserves th
26、e right to sample and to perform any confirmatory testing deemed necessary to ensure that the rings conform to the requirements of this specification.4.2 Classification of Tests: 4.2.1 Acceptance Tests: Tests for the following requirements are acceptance tests and shall be performed on each lot.SAE
27、INTERNATIONAL AMS7258B Page 5 of 12_ 4.2.2 Preproduction Tests: Tests for all technical requirements are preproduction tests and shall be performed prior to or on the first-article shipment of rings by a purchaser, when a change in ingredients and/or processing requires reapproval as in 4.4.2, and w
28、hen purchaser deems confirmatory testing to be required.4.2.2.1 For direct U.S. Military procurement, substantiating test data and, when requested, preproduction test material shall be submitted to the cognizant agency as directed by the procuring activity, contracting officer, or request for procur
29、ement.4.3 Sampling and Testing: Shall be as follows:4.3.1 For Acceptance Tests: Sufficient rings shall be taken at random from each lot to perform all required tests. The number of determinations for each requirement shall be as specified in the applicable test procedure or, if not specified therein
30、, not less than three. When specified, sample rings conforming to AS568-214 and hardness discs shall be supplied with each lot.4.3.1.1 Sample size for examination for appearance, workmanship, and dimensional conformance shall be in accordance with Inspection Level II of MIL-STD-105.4.3.1.2 A lot sha
31、ll be all rings of the same size produced from the same batch of compound in one continuous series of operations and presented for vendors inspection at one time but shall not exceed 1000 rings or 200 pounds (91 kg), whichever is the greater mass. A lot may be packaged in smaller quantities and deli
32、vered under the basic lot approval provided lot identification is maintained. 4.3.1.3 A batch shall be the quantity of compound run through a mill or mixer at one time.TABLE 2RequirementReferenceParagraphSpecific Gravity as receivedHardness as received Tensile Strength as receivedElongation as recei
33、ved Volume Change in Reference Fuel BCompression Set Examination for Surface ImperfectionsSizes and Tolerances 3.2.1.1 3.2.1.2 3.2.1.3 3.2.1.4 3.2.2.13.2.63.33.4 SAE INTERNATIONAL AMS7258B Page 6 of 12_ 4.3.1.4 When a statistical sampling plan other than specified in 4.3.1.1, has been agreed upon by
34、 purchaser and vendor, sampling shall be in accordance with such plan in lieu of sampling as in 4.3.1 and the report of 4.6 shall state that such plan was used.4.3.1.5 If rings smaller than AS568-010 are ordered, seven rings of -022 or -026 size shall be provided for determining tensile strength and
35、 elongation; such rings shall be from the same batch of compound, manufactured and, if required, post-cured under the same conditions as the production rings they represent.4.3.1.6 Compression set shall be determined on not less than two rings.4.3.2 For Preproduction Tests: Test samples shall be O-r
36、ings conforming in size to AS568-214 and hardness discs of at least 1/4 inch (6.4 mm) thickness.4.4 Approval: 4.4.1 Sample rings shall be approved by purchaser before rings for production use are supplied, unless such approval be waived by purchaser. Results of tests on production rings shall be ess
37、entially equivalent to those on the approved samples.4.4.2 Vendor shall use ingredients, manufacturing procedures, processes, and methods of inspection on production rings which are essentially the same as those used on the approved sample rings. If necessary to make any change in ingredients, in ty
38、pe of equipment for processing, or in manufacturing procedures, vendor shall submit for reapproval a statement of the proposed changes in ingredients and/or processing and, when requested, sample rings. Production rings made by the revised procedure shall not be shipped prior to receipt of reapprova
39、l.4.5 Test Methods: 4.5.1 Corrosion and Adhesion: Size -214 O-rings, two for each metallic plate below and using whole uncut rings, shall be prepared for corrosion testing by inserting sufficient quantities of the seals in a desiccator or similar humidity chamber maintained at relative humidity not
40、lower than 92% and 25 C 3 (77 F 5) for not less than 72 hours. Plates of the metals listed below shall be polished to a surface texture of 4 to 16 microinches (0.1 - 0.4 m), determined in accordance with ANSI B46.1. The edges shall also be polished to reduce the formation of edge corrosion. The plat
41、es shall be washed with toluene, aliphatic naphtha, or similar degreasing agent that will produce a clean dry surface free from film. The metals used shall be as follows:AMS 4037 or QQ-A-250/4 Aluminum AlloyAMS 4027 or QQ-A-250/11 Aluminum AlloyAMS 4045 or QQ-A-250/12 Aluminum AlloyAMS 5630 - Corros
42、ion Resistant SteelAMS 5513 - Corrosion Resistant SteelAMS 6350 or MIL-S-18729 Low-Alloy SteelSAE INTERNATIONAL AMS7258B Page 7 of 12_ 4.5.1.1 The humidified rings and the metallic plates shall be immersed in MIL-H-6083, Type I, fluid and drained to the drip point. The rings and plates shall be laid
43、 together in a stack so that at least two whole rings contact each specified metal. The stack shall be held together with a pressure of 20 - 30 pounds force (89 - 133 N) and placed in a desiccator maintained at relative humidity not lower than 92% at 25 C 3 (77 F 5). This relative humidity may be pr
44、oduced by the use of a salt of sufficient concentration in solution with distilled water. No more than 15 minutes should be required for assembling the test samples. Time of humidity exposure for this portion of test shall be 14 days. At the termination of this test, the procedures outlined below sh
45、all be followed:4.5.1.1.1 The surfaces of the plates which were in contact with the seals shall be inspected for discoloration, deposits, pitting, or other evidence of corrosion or adhesion. If any exist, the surfaces of the plates shall be washed in aliphatic naphtha. Deposits determined as rubber
46、compounds or elements therefrom, which can be removed by this process and which do not occur on other surfaces of the plates, shall be construed as adhesion.4.5.1.1.2 Any pits or eroded marks remaining after this process shall be construed to be corrosion. Discoloration or staining (marks which do n
47、ot physically affect the surfaces of the plates and which easily wash or buff off) shall not be considered detrimental. If any doubt should arise about the presence of pitting, erosion, or corrosion on the metal plates from the O-rings, visual examination at 10 to 15X magnification shall be used to determine the actual condition.4.5.2 Fuel Aging: The containers used for high-temperature fuel
