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 2015 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: +1 724-776-497
4、0 (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:/www.sae.org/technical/standards/MA2250 AEROSPACE STANDARD MA2250 Issued 1992-03 Reaffirmed 2015-08 Coupling Fuel,
5、 Flexible Variable Cavity, Threaded Type with Ferrules, Metric RATIONALE MA2250 has been reaffirmed to comply with the SAE five-year review policy. 1. SCOPE:1.1 Scope:This Aerospace Specification establishes the requirements for a threaded flexible coupling assembly, hereafter referred to as the ass
6、embly, which utilizes ferrules or machined tube end fittings to join tubing and components in aircraft fuel, vent, or other systems. This coupling assembly is designed for use from -54 to 93 C and at 862 kPa peak working pressure. AS coupling components referenced herein have been qualified to AS171
7、0. Ferrule referenced herein are inch ferrules adapted to metric tubing.2. REFERENCES:2.1 Applicable Documents:The following publications form a part of this specification to the extent specified herein.2.1.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.AS5
8、67 General Practices for Use of Lock Wire, Key Washers, and Cotter PinsAS568 Aerospace Size Standard for O-ringsAS1055 Fire Testing of Flexible Hose, Tube Assemblies, Coils, Fittings, and Similar System ComponentsAS1712 Coupling Subassembly, Flexible, Variable Cavity, Threaded, Ferrule Type Tube End
9、sAS1713 Half Coupling Subassembly, Flexible, Variable Cavity, Threaded, Ferrule Type Tube EndsSAE INTERNATIONAL MA2250 Page 2 of 25 2.1.1 (Continued):AS1714 Nut Assembly, Self-Locking, Coupling, Flexible, Variable Cavity, Threaded, Ferrule Type Tube EndsAS1715 Washer, Coupling, Flexible, Variable Ca
10、vity, Threaded, Ferrule Type Tube EndsAS1717 Retainer, Coupling, Flexible, Variable Cavity, Threaded, Ferrule Type Tube EndsAS1718 Coupling Body, Flexible, Variable Cavity Threaded, Ferrule Type Tube EndsAS1719 Fitting End, Half-Coupling, Flexible, Variable Cavity, Threaded, Ferrule Type, Design Sta
11、ndardAS1720 Ferrule End, Coupling, Flexible, Variable Cavity, Threaded, Ferrule Type, Design StandardMA2251 Coupling, Flexible, Variable Cavity, Threaded, Ferrule Type Tube Ends, Envelope Dimensions, MetricMA2256 Ferrule, Coupling, Flexible, Variable Cavity, Threaded, Ferrule Tube Ends, Metric2.1.2
12、U.S. Government: Available from Standardization Documents Order Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.PPP-T-60 Tape, Packaging, WaterproofPPP-B-566 Boxes, Folding, PaperboardPPP-B-576 Box, Wood, Cleated, Veneer, Paper OverlaidPPP-B-585 Boxes, Wood, WireboundPPP-B-591 Box
13、es, Shipping Fiberboard, Wood-CleatedPPP-B-601 Boxes, Wood, Cleated-PlywoodPPP-B-636 Boxes, Shipping FireboardPPP-B-665 Boxes, Paperboard, Metal-Edged and ComponentsPPP-B-676 Boxes, Set-UpVV-P-236 Petrolatum, TechnicalWW-T-700/6 Tube, Aluminum Alloy, Drawn, Seamless, 6061TT-S-735 Standard Test Fluid
14、s; HydrocarbonMIL-P-116 Preservation - Packaging, Methods ofMIL-S-7742 Screw Threads, Standard, Optimum Selected Series: General Specification forMIL-L-10547 Liners, Case and Sheet, Overwrap; Water-Vaporproof or Waterproof, FlexibleMIL-R-25988/1 Rubber, Fluorosilicone Elastomer, Oil and Fuel-Resista
15、nt, Sheets, Strips, Molded Parts, and Extruded ShapesMIL-STD-105 Sampling Procedures and Tables for Inspection by AttributesMIL-STD-129 Marking for Shipment and StorageMIL-STD-810 Environmental Test MethodsMIL-STD-831 Test Reports, Preparatioan ofMIL-STD-889 Dissimilar MetalsFED-STD-H28 Screw-Thread
16、s Standards for Federal ServicesSAE INTERNATIONAL MA2250 Page 3 of 25 3. TECHNICAL REQUIREMENTS:3.1 Qualification:Full coupling assemblies furnished under this specification shall be products which are qualified by meeting all of the requirements covered by this document. Manufacturers choosing to p
17、roduce only a part or parts of the coupling assembly shall qualify the part or parts by complying with the requirements and performing all tests of this document. The test specimens for qualification of a part or parts shall be completed with qualified part or parts made by another manufacturer. Hal
18、f coupling parts shall be qualified parts of the full coupling. Axial loading of the half coupling O-ring should be avoided and controlled by tubing installation.3.2 Materials and Finishes:Materials and finishes for the components shall be those designated on standards and drawings. Alternate materi
19、als and substitutions shall be approved by the purchaser. All materials and finishes shall be uniform in quality, free from defects, suitable for the purpose intended, and consistent with good manufacturing practices.3.2.1 Dissimilar Materials: Materials shall possess adequate corrosion-resistance c
20、haracteristics or shall be suitably protected by the use of finishes to resist corrosion which may result from such conditions as dissimilar metal combinations, moisture, salt spray, and high temperature deterioration. Dissimilar materials are defined by MIL-STD-889.3.3 Design and Fabrication:The co
21、upling shall be a lightweight, flexible connection with an O-ring seal. It shall be designed for engine feed, pressure fueling or similar applications at 862 kPa static working pressure in sizes up through 100 and for 207 kPa for dump and vent lines in sizes from 114 up to and including size 140. Th
22、e coupling shall operate at temperature extremes of -54 to 93 C at static pressures, and -40 to 57 C for pressure surging and dynamic operation during fueling and flight. The coupling shall function at a maximum misalignment of 4 or with a maximum gap of 6 mm or in combination, a minimum gap of 1.6
23、mm at a 3 misalignment.SAE INTERNATIONAL MA2250 Page 4 of 25 3.3.1 Coupling Components: The coupling assembly shall consist of the following components.3.3.2 Threads: Threads of nut and body shall be in accordance with Federal Standard H28/2.3.3.3 Seals: O-rings are not considered a part of this doc
24、ument except for coupling qualification test requirements. O-ring sizes for the couplings are given in Table 2.SAE INTERNATIONAL MA2250 Page 5 of 25 SAE INTERNATIONAL MA2250 Page 6 of 25 3.3.4 Dimensions: The coupling assembly envelope dimensions shall be as specified in MA2251. Part dimensions shal
25、l be as specified in applicable part standards.3.3.4.1 Coupling Weight: The coupling assembly and components shall not exceed the maximum weights listed on the applicable part standard drawing.3.4 Performance:The coupling assembly shall meet the following performance requirements:3.4.1 Leakage:3.4.1
26、.1 Pneumatic Leakage: The assembly shall withstand pneumatic pressure equal to the maximum proof pressure of Table 2 for 3 min at room temperature without any visible bubbles starting after 1 min at pressure or other malfunction, which would affect assembly or disassembly when tested in accordance w
27、ith 4.6.2.2.1.3.4.1.2 Liquid Leakage: The assembly when subjected to the tests specified herein shall not allow the escape of fluid or external wetting sufficient to form a drop from any point of the fitting assembly including the fitting-tube junction. This junction is defined to include one tube o
28、utside diameter in length beyond the coupling envelope. The envelope is the area from free parent tube material to free parent tube material, boss, or coupling.3.4.2 Proof Pressure: The assembly shall meet the negative and positive proof pressures listed per 3.4.1 in Table 2. A decrease in negative
29、pressure exceeding .001 kPa within 5 min, leakage per 3.4.1 when pressurized, or evidence of any other malfunction shall be cause for rejection. The test method is specified in 4.6.2.3.4.3 Fuel Resistance: The coupling assembly shall not leak in excess of 3.4.1 nor show evidence of malfunction when
30、subjected to fuel resistance testing at high temperature fuel aging (93 C), low temperature fuel aging (-54 C), and air dry out (93 C). The test procedure and duration of aging is referenced in 4.6.3.3.4.4 Vibration: The assembly, when pressurized per 4.6.4, shall show no evidence of malfunction or
31、structural failure and shall not leak in excess of 3.4.1 when pressurized to the proof pressure requirements of 3.4.2 after exposure to vibration levels in accordance with 4.6.4.3.4.5 Salt Fog: The assembly shall not leak in excess of 3.4.1, when proof tested to the requirements of 3.4.2 and shall s
32、how no evidence of excessive corrosion, peeling, chipping or blistering of the finish, or exposure of base metal under plated surfaces after being subjected to the salt fog test. The test method is specified in 4.6.5.SAE INTERNATIONAL MA2250 Page 7 of 25 3.4.6 Flexure: The assembly shall withstand t
33、he Table 2 negative and positive proof pressures after being subjected to a total of 50 000 flexure cycles at room temperature. A decrease in negative pressure exceeding 1.7 kPa within 5 min, leakage in excess of 3.4.1 when pressurized for a minimum of 5 min, or evidence of any other malfunction sha
34、ll be a cause for rejection. Leakage at -40 C if observed shall be recorded; it is not cause for rejection. Flexure shall be .5 from an initial misaligned position of 3. Testing is specified in 4.6.6.3.4.7 Pressure Surge: The assembly shall withstand 50 000 pressure surge cycles as defined in Figure
35、 4 and in Table 2 without evidence of malfunction or leakage in excess of 3.4.1. Testing is specified in 4.6.7.3.4.8 Burst Pressure:3.4.8.1 Burst Pressure Test at Temperature Extremes: The assembly shall not rupture nor show evidence of leakage in excess of 3.4.1 at any pressure up to the Table 2 bu
36、rst pressures and at the two temperature extremes of -54 to 93 C. The test procedure is specified in 4.6.8.1.3.4.8.2 Burst at Room Temperature: The assembly shall be pressurized to rupture at room temperature. There shall be no evidence of leakage in excess of 3.4.1 at any pressure up to the burst t
37、est pressures listed in Table 2. The pressure at which rupture occurs shall be above the values listed in Table 2. The test procedure is specified in 4.6.8.2.3.5 Marking:Coupling assemblies and parts shall be marked for identification in accordance with the applicable AS or MA standard or drawing.3.
38、6 Workmanship:Coupling components shall be manufactured and finished in accordance with commercially accepted practices and processes.3.7 Cleaning:The coupling assemblies as supplied shall be free of oil, grease, dirt, or any other foreign material both internally and externally.SAE INTERNATIONAL MA
39、2250 Page 8 of 25 4. QUALITY ASSURANCE PROVISIONS:4.1 Responsibility for Inspection:Unless otherwise specified in the contract or purchase order, the supplier is responsible for the performance of all inspection and test requirements as specified herein. Except as otherwise specified, the supplier m
40、ay utilize his own facilities or any commercial laboratory acceptable to the purchaser for the performance of the inspection and test requirement. The purchaser reserves the right to perform any of the inspections and tests set forth in the specification, where such inspections and tests are deemed
41、necessary to assure supplies and services conform to prescribed requirements.4.2 Classification of Inspections:The examining and testing of assemblies shall be classified as:a. a.Qualification inspections (see 4.3)b. b.Quality conformance inspections (see 4.4)4.3 Qualification Inspections:4.3.1 Qual
42、ification Test Specimens: Test specimens shall be in accordance with Figure 1 and Table 3. The number of specimens are specified in 4.3.2. Tubing for fabrication of test specimens shall be 6061-T4 in accordance with WW-T-700/6 with wall thickness as shown in Table 4. O-rings per MIL-R-25988/1 shall
43、be used for qualification testing of all specimens.SAE INTERNATIONAL MA2250 Page 9 of 25 SAE INTERNATIONAL MA2250 Page 10 of 25 4.3.2 Test Schedule and Sequence: Eight test specimens for each of the coupling sizes 12, 25, 50, 76, 100, and 124 shall be subjected to qualification tests in the order in
44、dicated in Table 5.4.3.3 Test Report, Test Samples, and Data for the Purchaser: Unless the tests are conducted by the purchaser, the following shall be furnished by the supplier:4.3.3.1 Test Report: Three copies of a test report in accordance with MIL-STD-831, which shall include a report of all tes
45、ts and describe the tests and conditions, shall be furnished. (See Note.)SAE INTERNATIONAL MA2250 Page 11 of 25 4.3.3.2 Test Samples: Test samples shall be furnished when requested by the purchaser. Samples subjected to qualification testing shall not be shipped as part of the contract or order.4.3.
46、3.3 Drawings: Three sets of assembly and subassembly drawings shall be furnished. The assembly drawings shall have a cutaway of the section showing all details in their normal assembly position and shall carry part numbers of all details and subassemblies.NOTE: Log sheets and recorded test data shal
47、l remain on file at the source test facility and are not sent to the purchaser unless specifically requested.4.3.4 Qualification Inspection Methods: Qualification inspection methods shall consist of all the examinations and tests specified under 4.6.4.4 Quality Conformance Inspections:Quality confor
48、mance inspections shall be in accordance with MIL-STD-105 and 4.4.1 and 4.4.2. Each coupling part shall be subjected to examination of product as specified in 4.6.1. Any coupling failing to pass the examination shall be rejected.4.4.1 Sample Size and Distribution: The sample size shall be as specifi
49、ed in accordance withMIL-STD-105. The classes, AQLs and defect characteristics referred to in MIL-STD-105 are further defined in Tables 6 and 7.SAE INTERNATIONAL MA2250 Page 12 of 25 4.4.2 Classification of Defects:SAE INTERNATIONAL MA2250 Page 13 of 25 4.4.3 Rejection and Retest: Where one or more items selected from a lot fails to meet the specification, all items in the lot shall be inspected.4.4.3.1 Resubmitted Lots: Once a lo
