ISO 8829-1:2009

INTERNATIONAL ISO
STANDARD 8829-1
First edition
2009-04-01
Aerospace — Test methods for
polytetrafluoroethylene (PTFE) inner-tube
hose assemblies —
Part 1:
Metallic (stainless steel) braid
Aéronautique et espace — Méthodes d'essai des tuyauteries flexibles à
tube intérieur en polytétrafluoroéthylène (PTFE) —
Partie 1: Tresses métalliques (en acier inoxydable)

Reference number
©
ISO 2009
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2009
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 microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2009 – All rights reserved

Contents Page
Foreword. iv
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Tests of PTFE inner tubes .2
4.1 Density and relative density .2
4.2 Tensile tests .2
4.3 Rolling and proof pressure tests .4
4.4 Electrical conductivity test .6
5 Tests on hoses and hose assemblies .7
5.1 Stress degradation test.7
5.2 Pneumatic effusion test .7
5.3 Electrical conductivity test .8
5.4 Visual and dimensional inspection.10
5.5 Determination of elongation or contraction.10
5.6 Volumetric expansion test.11
5.7 Leakage test .12
5.8 Proof pressure test.12
5.9 Burst pressure tests.13
5.10 Impulse test.13
5.11 Flexure test.14
5.12 Fuel resistance test .14
5.13 Low temperature flexure testing .15
5.14 Pneumatic leakage test .15
5.15 Vacuum test.16
5.16 Pneumatic surge test .16
5.17 Thermal shock test .17
5.18 Fire test .17
Annex A (informative) Test fluids .18
Bibliography .19

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
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. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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 least 75 % of the member bodies casting a vote.
ISO 8829-1 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 10, Aerospace fluid systems and components.
ISO 8829 consists of the following parts, under the general title Aerospace — Test methods for
polytetrafluoroethylene (PTFE) inner-tube hose assemblies:
⎯ Part 1: Metallic (stainless steel) braid
⎯ Part 2: Non-metallic braid
iv © ISO 2009 – All rights reserved

INTERNATIONAL STANDARD ISO 8829-1:2009(E)

Aerospace — Test methods for polytetrafluoroethylene (PTFE)
inner-tube hose assemblies —
Part 1:
Metallic (stainless steel) braid
1 Scope
This part of ISO 8829 specifies test methods for flexible polytetrafluoroethylene (PTFE) inner tubes with
metallic (stainless steel) braided hose and hose assemblies used in aircraft fluid systems, in the pressure and
temperature ranges covered by pressure classes and temperature types, as specified in ISO 6771.
If performance requirements are not defined in this part of ISO 8829, they are defined in the performance
specification.
This part of ISO 8829 is applicable when reference is made to it in a procurement specification or other
definition document.
NOTE Fluids used for the tests are listed in Annex A. The requirements for non-metallic braid hose assemblies are
given in ISO 8829-2.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 2685, Aircraft — Environmental test procedure for airborne equipment — Resistance to fire in designated
fire zones
ISO 6772, Aerospace — Fluid systems — Impulse testing of hydraulic hose, tubing and fitting assemblies
ISO 6773, Aerospace — Fluid systems — Thermal shock testing of piping and fittings
ISO 7258, Polytetrafluoroethylene (PTFE) tubing for aerospace applications — Methods for the determination
of the density and relative density
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
room temperature
temperature in the test laboratory between 15 °C (59 °F) and 32 °C (90 °F)
3.2
fire protection
flame- and heat-retardant element over the hose assembly
4 Tests of PTFE inner tubes
4.1 Density and relative density
4.1.1 Principle
This test is intended to control the crystallinity of PTFE inner tubes.
4.1.2 Test methods
The relative density of the PTFE tubing shall be measured in accordance with ISO 7258, method A or
method B. The density of the PTFE tubing shall be measured in accordance with ISO 7258, method C.
4.2 Tensile tests
4.2.1 Principle
This test is intended to determine the mechanical properties of the PTFE tubing.
4.2.2 Test conditions
Test specimens shall be conditioned for at least 2 h at room temperature prior to testing.
4.2.3 Apparatus
4.2.3.1 Testing machine
The test shall be carried out using a power-driven machine which is capable of maintaining a uniform rate of
jaw separation at 50 mm/min (2 in/min) and which has a suitable dynamometer and a device for measuring
the force applied within ± 2 %. If the capacity range cannot be changed during a test, as in the case of
pendulum dynamometers, the force applied at breaking point shall be measured within ± 2 %, and the
smallest tensile force measured shall be accurate to within ± 10 %.
If the dynamometer is of the compensating type for measuring tensile stress directly, means shall be provided
to make adjustments for the cross-sectional area of the test specimen. The response of the recorder shall be
sufficiently rapid that the force applied is measured accurately during the elongation of the test specimen to
breaking point. If the test machine is not equipped with a recorder, a device shall be provided that indicates,
after fracture, the maximum force applied during elongation. Testing machines shall be capable of measuring
elongation in increments of 10 %.
4.2.3.2 Micrometer
The micrometer used for measuring flat test specimen thickness shall be capable of exerting a pressure of
(25 ± 5) kPa [(3,63 ± 0,7) psi] on the test specimens and of measuring the thickness to within ± 0,025 mm
(0,001 in).
NOTE Dial micrometers exerting either a force of (0,8 ± 0,15) N [(0,18 ± 0,034) lbf] on a circular foot 6,35 mm
(0,25 in) in diameter, or a force of (0,2 ± 0,04) N [(0,045 ± 0,009) lbf] on a circular foot 3,2 mm (0,125 in) in diameter,
conform to the pressure requirement specified above. It is not advisable to use a micrometer to measure the thickness of
test specimens narrower in width than the diameter of the foot unless the contact pressure is properly adjusted.
4.2.4 Calibration of testing machine
The testing machine shall be calibrated.
2 © ISO 2009 – All rights reserved

If the dynamometer is of the strain-gauge type, the test machine shall be calibrated at one or more forces at
regular intervals.
4.2.5 Test specimens
The specimens shall be in accordance with Figure 1.
NOTE Careful maintenance of the cutting edges of the die is extremely important and can be achieved by light daily
honing and touching up of the cutting edges with jeweller’s hard honing stones. The condition of the die can be assessed
by determining the breaking point on any series of broken test specimens. When broken test specimens are removed from
the jaws of the test machine, it is advantageous to pile these test specimens and note if there is any tendency to break at
or near the same portion of each test specimen. Breaking points consistently occurring at the same place can be an
indication that the die is dull, nicked or bent at that particular position.
Dimensions in millimetres
Figure 1 — Test specimen for tensile test
4.2.6 Determination of tensile strength and elongation
4.2.6.1 Procedure
Place the test specimens (see 4.2.5) in the jaws of the testing machine (see 4.2.3.1), taking care to adjust the
specimen symmetrically so that the tension will be distributed uniformly over the cross-section. Start the
machine and note continuously the distance between the jaws, taking care to avoid parallax. At fracture,
measure and record the elongation to the nearest 10 % on the scale.
4.2.6.2 Expression of results
1)
Calculate the tensile strength, R , expressed in newtons per square millimetre , using Equation (1):
m
F
R = (1)
m
S
where
F is the measured force, in newtons, required to fracture the test specimens;
S is the cross-sectional area, in square millimetres, of the test specimen before application of force.

1) 1 N/mm = 1 MPa.
Calculate the percentage total elongation at f
...