1、INTERNATIONAL STANDARD IS0 9938 Second edition 1994-12-15 Aerospace - Polytetrafluoroethylene (PTFE) hose assemblies, classification 204 “C/28 000 kPa - Procurement specification ABronautique et espace - Tuyauteries flexibles en polytt+trafluoro6thyl6ne (PTFE), classification 204 “C/28 000 kPa - Spk
2、cification dapprovisionnement Reference number IS0 9938.1994(E) IS0 9938:1994(E) Foreword IS.0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out throug
3、h IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborat
4、es closely with the International Electrotechnical Commission IIEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at l
5、east 75 % of the member bodies casting a vote. International Standard IS0 9938 was prepared by Technical Committee lSO/TC 20, Aircraft and space vehicles, Subcommittee SC IO, Aerospace fluid systems and components. This second edition cancels and replaces the first edition (IS0 9938:1990), of which
6、it constitutes a technical revision. Annex A of this International Standard is for information only. 0 IS0 1994 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and
7、 microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56 l CH-1211 Geneve 20 l Switzerland Printed in Switzerland ii INTERNATIONAL STANDARD 0 IS0 IS0 9938: 1994(E) Aerospace - Polytetrafluoroethylene (PTFE) hose assemblies, classifi
8、cation 204 “C/28 000 kPa - Procurement specification 1 Scope This International Standard specifies requirements for polytetrafluoroethylene (PTFE) hose assemblies for use in aircraft hydraulic systems at temperatures be- tween - 55 “C and + 204 “C and at a nominal press- ure up to 28 000 kPa (280 ba
9、r). The hose assemblies are also suitable for use within the same temperature and pressure limitations in aircraft pneumatic systems where some gaseous diffusion through the wall of the PTFE liner may be tolerated. The use of these hose assemblies in high-pressure pneumatic storage systems is not re
10、commended. In addition, installations in which the limits specified in this International Standard are exceeded, or in which the application is not covered specifically by this In- ternational Standard, for example for oxygen, shall be subject to the approval of the purchaser. 2 Normative references
11、 The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Stand
12、ard are encouraged to investigate the possibility of applying the most re- cent editions of the standards indicated below. Members of IEC and IS0 maintain registers of cur- rently valid International Standards. IS0 2685:1992, Aircraft - Environmental conditions and test procedures for airborne equip
13、ment - Re- sistance to fire in designated fire zones. IS0 2859-l : 1989, Sampling procedures foi inspection by attributes - Part I: Sampling plans indexed by acceptable quality level (AQL) for lot-by-lot inspection. IS0 5855-3:1988, Aerospace - MJ threads - Part 3: Limit dimensions for fittings for
14、fluid systems. IS0 6772:1988, Aerospace - Fluid systems - Im- pulse testing of hydraulic hose, tubing and fitting as- semblies. I SO 7258: 1984, Polyte trafluoroeth ylene (PTFE) tubing for aerospace applications - Methods for the deter- mination of the density and relative density. I SO 8829: 1990,
15、Aerospace - Polytetrafluoroeth ylene IPTFEI hose assemblies - Test methods. 3 Requirements 3.1 Qualification Hose assemblies supplied in accordance with this In- ternational Standard shall be representative of prod- ucts which have been subjected to and which have successfully passed the requirement
16、s and tests specified in this International Standard. 1 IS0 9938:1994(E) Q IS0 3.2 Materials 3.2.1 General The hose assembly materials shall be as described in this International Standard (see, in particular, annex A). All materials not specifically described in this International Standard shall be
17、of the highest quality and suitable for the purpose intended. 3.2.2 Metals Metals used in the hose and fittings shall be corrosion-resistant or titanium and shall conform to the applicable specifications described in table 1 (or equivalent specifications; see annex A). Table 1 - Metals to be used in
18、 hose assemblies Austenitic, annealed or as-rolled, stabilized, corrosion-resistant steel Precipitation-hardening, corrosion- Titanium 6AI-N 7 Austenitic, seamless or welded, annealed, corrosion-resistant steel 8 Tubing Austenitic, seamless or welded, stabilized, corrosion-resistant steel 9 and 10 C
19、old-worked, stress-relieved titanium alloy 11 Wire Austenitic, cold-drawn, corrosion- 12, 13 and resistant steel 14 3.3 Construction 3.3.1 General The hose assembly shall consist of - a seamless PTFE inner tube (see 3.3.21, - corrosion-resistant steel-wire reinforcement (see 3.3.31, and - corrosion-
20、resistant steel and/or titanium end- fittings (see 3.3.41, as required to meet the construction and performance requirements laid down in this International Standard and as required for its intended use. 3.3.2 Inner tube The inner tube shall be of a seamless construction of virgin PTFE resin of unif
21、orm gauge; it shall have a smooth bore and shall be free from pitting or pro- jections on the inner surface. Additives may be in- cluded in the compound from which the tube is extruded with no more than 2 % of such additives being retained in the mixture. 3.3.3 Reinforcement The reinforcement shall
22、consist of corrosion-resistant steel wire conforming to the applicable specifications given in 3.2.2. The wires shall be arranged on the outside surface of the inner tube so as to provide sufficient strength to ensure compliance with the re- quirements laid down in this International Standard. Broke
23、n or missing reinforcing wires or buckled wires more than 1,5 mm above the outside diameter sur- face shall be cause for rejection. Overlapping or crossed-over reinforcing wires shall not be cause for rejection of the flexible hose assembly. 3.3.4 Fittings 3.3.4.1 General It shall be proven that all
24、 fittings comply with the re- quirements laid down in this International Standard. Unless otherwise specified by the purchaser, the hose assemblies shall have flareless fittings (24” cone coupling). NOTE 1 An International Standard (IS0 7321) specifying the geometric definition of a 24” cone couplin
25、g is currently being prepared. 3.3.4.2 Insert fittings Insert fittings shall be manufactured in one piece wherever possible. Those made of other than one- piece construction shall be butt-welded, unless otherwise agreed by the purchaser, fabricated from corrosion-resistant steel tubing or titanium.
26、Welded 2 0 IS0 IS0 9938:1994(E) and redrawn tubing (materials Nos. 8 and 9; see an- nex A) may be used for corrosion-resistant steel. 3.4 Inner tube requirements a) 10 .IA for sizes DN06 to DN12 (inclusive); b) 20 PA for sizes DN16 and over. 3.5 Hose 3.4.1 Density and relative density 3.5.1 Dimensio
27、nal requirements The relative density of the hose inner tube shall not exceed 2,155, when tested in accordance with IS0 7258, either method A or method B (as specified in IS0 8829). The density shall not exceed 2,204 g/cm3, when tested in accordance with IS0 7258, method C (as specified in IS0 8829)
28、 3.4.2 Tensile strength When tested in accordance with IS0 8829:1990, subclause 4.2, the longitudinal tensile strength for all sizes of tubes shall be at least 15,l N/mm*“. When tested in accordance with IS0 8829:1990, subclause 4.2, the transverse tensile strength for sizes DNI 6 and larger shall b
29、e at least 12,4 N/mm*; for sizes under DN16, the transverse strength need not be tested. 3.4.3 Elongation When tested in accordance with IS0 8829:1990, subclause 4.2, the elongation shall be at least 200 %. 3.4.4 Tube roll The tube shall not leak, split, burst or show any signs of malfunction, when
30、tested through the sequence as specified in IS0 8829:1990, subclause 4.3.2. 3.4.5 Tube proof-pressure After being subjected to the tube roll test sequence (see 3.4.41, the tube, without reinforcing wires, shall not leak, burst or show any signs of malfunction, when tested as specified in IS0 8829:19
31、90, sub- clause 4.3.3. The hose assembly dimensions, except for length, shall be as specified in figure 1 and table2. 3.5.2 Physical requirements Hose assemblies shall comply with the physical and linear density (weight) requirements specified in table 3. 3.5.3 Bore check When bent to the appropriat
32、e minimum bend radius as specified in table3, the hose assembly shall permit the free passage of a solid rigid sphere throughout its length. The diameter of the sphere shall be 90 % of the appropriate minimum internal diameter of the end fittings as specified in table2. For elbow fittings, see footn
33、ote I) to table 2. 3.6 Screw threads Unless otherwise specified (see 3.3.41, fitting threads shall be in accordance with IS0 5855-3. A 10 % in- crease in the tolerance of the fitting thread of the nut following proof testing shall not be cause for rejection of the hose assembly. 3.7 Part numbering o
34、f interchangeable parts All parts complying with this International Standard and having the same manufacturers or standard part number shall be functionally and dimensionally inter- changeable. 3.8 Identification of products 3.4.6 Electrical conductivity 3.8.1 General When tested in accordance with
35、IS0 8829:1990, subclause 4.4, the electrical current shall be equal to or greater than The hose assembly and its component parts shall be permanently marked. *) 1 N/mm2 = 1 MPa 3 IS0 9938:1994(E) Figure 1 - Hose and fitting dimensions Table 2 - Hose and fitting dimensions (see figure 1) Hose size (n
36、om.) DN06 5,4 1 IO,; 1 12,6 3,4 I 23 58 DNIO 73 14,0 15,8 DN12 93 17.0 20,9 DN16 DN20 DN25 21,6 30.7 38,l 19.3 51 Hose (braided) Fitting Inside diameter Outside diameter 4 Dh min min I max 123 I 21,6 1 24.6 IQ4 I 36 76 15.3 I 25.1 1 30.5 12,9 I 43 Inside Outside diameter) diametern) 4 4 min. max 6,l
37、 1 26 64 8.6 1 31 1) Minimum inside diameter through the elbow area may be 85 % of the values given for 4. 2) Width across corners of nut and socket hexagon may exceed the values given for Df Dimensions in millimetres Attachment length 1 max. 70 83 96 Wall thickness of inner tube 6 min. 0,9 1 1.1 Ta
38、ble 3 - Physical requirements of hose assemblies and linear density (weight) of hose Hose Burst pressure Bend radius Operating Proof at inside of Volumetric weight) Room High Hose size pressure pressure bend expansion temperature temperature max min min. min. max kg/m kPa kPa kPa kPa mm ml/m DN06 08
39、4 76 3.2 DNIO 0.66 127 4.7 DN12 0,81 28 000 56 000 112000 84 000 146 687 DN16 I,25 165 IO,8 DN20 I,7 197 14,8 DN25 2,86 245 37 1) Hose weight shall be determined on a minimum length of 300 mm CJ IS0 IS0 9938:1994(E) 3.8.2 Fittings The manufacturers name or trademark shall be per- manently marked on
40、one element of all end fittings. 3.8.3 Hose assembly A permanent marking shall be applied on a fitting or on a permanent band or bands securely attached to the hose. Bands shall be no wider than 25 mm and shall not impair the flexibility or the performance of the hose. Unless otherwise specified, th
41、e marking on the fitting or band shall include the following infor- mation: a) the assembly manufacturers name or trademark, and the number of this International Standard, b) the complete hose assembly part number; c) the nominal pressure “28 000 kPa”, as applicable; d) the operating temperature, “2
42、04 “C”, if required; e) the pressure test symbol, “PT”; f) the date of hose assembly manufacture, ex- pressed in terms of month and year, or batch number. 3.9 Workmanship 3.9.1 General Workmanship shall be of such quality as to assure that hose assemblies furnished under this specifi- cation are fre
43、e of defects that compromise, limit or reduce performance or intended use. Hose assemblies shall be free of burrs, scratches, sharp edges, loose components, chips or foreign ma- terials. 3.9.2 Dimensions and tolerances All pertinent dimensions and tolerances, where inter- changeability, operation or
44、 performance of the hose assembly may be affected, shall be specified on ail drawings. 3.9.3 Cleaning All hose assemblies shall be free from oil, grease, dirt or other foreign materials, both internally and ex- ternally. 3.10 Hose assembly - Test and performance requirements 3.10.1 Proof pressure Wh
45、en tested in accordance with IS0 8829:1990, subclause 5.8, each hose assembly shall withstand the proof pressure specified in table3 without mal- function or leakage. 3.10.2 Elongation and contraction When two test specimens of the sample hose as- semblies are tested in accordance with IS0 8829:1990
46、, subclause 5.5, there shall be no change in length by more than + 2 % in a 250 mm gauge length. 3.10.3 Volumetric expansion When two test specimens of the sample hose as- semblies are tested in accordance with IS0 8829:1990, subclause 5.6, the volumetric expan- sion shall not exceed the limits spec
47、ified in table3. 3.10.4 Leakage When two test specimens of the sample hose as- semblies are tested in accordance with IS0 8829:1990, subclause 5.7, there shall be no leakage. 3.10.5 Thermal shock 3.10.5.1 Preconditioning Two test specimens of the sample hose assemblies shall be tested: one test spec
48、imen shall be air-aged and the other shall be unaged (see 4.5.6). 3.10.5.2 Requirement When tested in accordance with IS0 8829:1990, subclause 5.17, the test specimens shall neither leak nor show any signs of malfunction during the proof pressure phase of the test; during the burst pressure phase of
49、 the test, if leakage or signs of malfunction occur below the minimum burst pressure at the high temperature specified in table3, the samples shall be deemed to have failed. 5 IS0 9938:1994(E) 0 IS0 3.10.6 Impulse Dimensions in millimetres Inside bend radius, r 7 3.10.6.1 Preconditioning Six sample hose assemblies having a 90” elbow fitting on one end of the hose and a straight fitting on the other end of the hose shall be tested. Two test specimens shall be oil-aged, two air-aged, and two unaged (see 4.5.6). After this initial preconditi
