ISO 8829-2:2006

Aerospace — Test methods for polytetrafluoroethylene (PTFE) inner-tube hose assemblies — Part 2: Non-metallic braid

ISO 8829-2:2006 specifies test methods for flexible polytetrafluoroethylene (PTFE) inner tubes with non-metallic 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. ISO 8829-2:2006 applies to the hose and the hose coupling. The tests and assembly requirements for the connecting end fittings are covered in the procurement specification. ISO 8829-2:2006 is applicable when reference is made to it in a procurement specification or other definition document.

Aéronautique et espace — Méthodes d'essai des tuyauteries flexibles à tube intérieur en polytétrafluoréthylène (PTFE) — Partie 2: Tuyauteries à gaine non métallique

General Information

• Status: Published
• Publication Date: 21-Sep-2006
• ICS: 49.080 - Aerospace fluid systems and components
• ICS: 83.140.40 - Hoses
• Technical Committee: ISO/TC 20/SC 10 - Aerospace fluid systems and components
• Drafting Committee: ISO/TC 20/SC 10/WG 14 - Hose assemblies
• Current Stage: 9020 - International Standard under periodical review
• Start Date: 15-Oct-2025
• Completion Date: 15-Oct-2025

Relations

• Revises: ISO 8829:1990 - Aerospace — Polytetrafluoroethylene (PTFE) hose assemblies — Test methods
• Effective Date: 15-Apr-2008

Overview

ISO 8829-2:2006 - “Aerospace - Test methods for polytetrafluoroethylene (PTFE) inner‑tube hose assemblies - Part 2: Non‑metallic braid” defines standardized test methods for flexible PTFE inner tubes with non‑metallic braided covers used in aircraft fluid systems. The standard specifies how to qualify hoses and hose assemblies (including the hose coupling) across the relevant pressure classes and temperature types (as referenced in ISO 6771). Tests simulate demanding in‑service conditions so assemblies used in safety‑critical systems meet repeatable, auditable performance criteria.

Key topics and technical requirements

• Scope & applicability
  • Applies when referenced in procurement or specification documents.
  • Covers hose and hose coupling; connecting end fitting assembly requirements are handled in procurement specifications.
• Test environment
  • Standard test temperature range: 15 °C to 32 °C (59 °F to 90 °F).
• Material and tube tests
  • Density and relative density (crystallinity control) per ISO 7258.
  • Tensile testing of PTFE tubing (strength and elongation) with defined specimen geometry and test procedures.
  • Rolling tests to detect sintered‑tube flaws followed by proof‑pressure tests.
  • Electrical conductivity checks for applicable constructions.
• Hose and assembly tests
  • Stress‑degradation, pneumatic effusion, pneumatic leakage and vacuum tests.
  • Volumetric expansion, leakage, proof‑pressure and burst‑pressure tests.
  • Dynamic tests: impulse, pneumatic surge, flexure, push‑pull and low‑temperature flexure.
  • Environmental aging: thermal shock, light‑radiation aging, fuel resistance and fire testing.
• Supporting information
  • Annex A lists recommended test fluids.
  • Normative references include ISO 6771 (pressure/temperature classifications), ISO 6772/6773 (impulse and thermal shock), ISO 7258 and others.

Practical applications

• Use ISO 8829-2:2006 to:
  • Qualify PTFE inner‑tube hose assemblies with non‑metallic braids for hydraulic, fuel, oil and pneumatic systems in aircraft.
  • Establish acceptance criteria in procurement specifications for aerospace OEMs and suppliers.
  • Define laboratory test programs for component qualification, quality assurance and certification evidence.
• Typical users:
  • Aerospace OEMs and Tier‑1 suppliers, hose manufacturers, test laboratories, procurement and quality engineers, and certification authorities.

Related standards

• ISO 8829-1 (Part 1: Metallic (stainless steel) braid)
• ISO 6771 (Aerospace fluid systems - Pressure and temperature classifications)
• ISO 7258 (PTFE tubing density tests)
• ISO 6772, ISO 6773 (impulse and thermal shock test methods)
• ISO 2685 (resistance to fire in designated zones)

Keywords: ISO 8829-2:2006, PTFE inner-tube hose assemblies, non‑metallic braid, aerospace hose tests, proof-pressure, burst-pressure, impulse test, flexure test, hose qualification.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 8829-2
First edition
2006-09-15
Aerospace — Test methods for
polytetrafluoroethylene (PTFE) inner-tube
hose assemblies —
Part 2:
Non-metallic braid
Aéronautique et espace — Méthodes d'essai des tuyauteries flexibles
à tube intérieur en polytétrafluoroéthylène (PTFE) —
Partie 2: Tuyauteries à gaine non métallique

Reference number
©
ISO 2006
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ii © ISO 2006 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Test temperature. 2
5 Tests on PTFE inner tubes . 2
5.1 Density and relative density . 2
5.2 Tensile tests . 2
5.3 Rolling and proof-pressure tests . 4
5.4 Electrical conductivity test . 6
6 Test on hoses and hose assemblies . 6
6.1 Stress degradation test. 6
6.2 Pneumatic effusion test . 8
6.3 Electrical conductivity test . 9
6.4 Visual and dimensional inspection. 10
6.5 Determination of elongation or contraction. 10
6.6 Volumetric expansion test . 10
6.7 Leakage test . 12
6.8 Proof-pressure test. 12
6.9 Burst-pressure tests. 12
6.10 Impulse test . 13
6.11 Flexure test. 13
6.12 Fuel resistance test . 15
6.13 Low-temperature flexure testing . 15
6.14 Pneumatic leakage test . 15
6.15 Vacuum test. 15
6.16 Pneumatic surge test. 16
6.17 Thermal shock test . 16
6.18 Light-radiation aging . 17
6.19 Push-pull test . 18
6.20 Fire test . 19
Annex A (informative) Test fluids . 20
Bibliography . 21

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.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 8829-2 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 10, Aerospace fluid systems and components.
ISO 8829-2 cancels and replaces ISO 8829:1990, which has been technically revised.
ISO 8829 consists of the following parts, under the general title Aerospace — Test methods for polytetra-
fluoroethylene (PTFE) inner-tube hose assemblies:
⎯ Part 1: Metallic (stainless steel) braid
⎯ Part 2: Non-metallic braid
iv © ISO 2006 – All rights reserved

Introduction
This part of ISO 8829 is intended to standardize the test methods for qualification of polytetrafluoroethylene
(PTFE) hose and hose assemblies used in aircraft fluid systems. The tests are intended to simulate the most
strenuous demands encountered in aircraft. Compliance with these test methods is necessary for hose and
hose assemblies which are used in systems where a malfunction could affect the safety of flight.

INTERNATIONAL STANDARD ISO 8829-2:2006(E)

Aerospace — Test methods for polytetrafluoroethylene (PTFE)
inner-tube hose assemblies —
Part 2:
Non-metallic braid
1 Scope
This part of ISO 8829 specifies test methods for flexible polytetrafluoroethylene (PTFE) inner tubes with
non-metallic 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.
This part of ISO 8829 applies to the hose and the hose coupling. The tests and assembly requirements for the
connecting end fittings are covered in the procurement 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.
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 2685:1998, Aircraft — Environmental test procedure for airborne equipment — Resistance to fire in
designated fire zones
1)
ISO 6771 , Aerospace — Fluid systems and components — Pressure and temperature classifications
ISO 6772:1988, Aerospace — Fluid systems — Impulse testing of hydraulic hose, tubing and fitting
assemblies
ISO 6773:1994, Aerospace — Fluid systems — Thermal shock testing of piping and fittings
ISO 7258:1984, Polytetrafluoroethylene (PTFE) tubing for aerospace applications — Methods for the
determination of the density and relative density

1) To be published. (Revision of ISO 6771:1987)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
fire sleeve
flame- and heat-retardant element, normally tubular, slipped over the hose assembly and fastened to the hose
fitting
3.2
fire-cover
flame- and fire-retardant element, normally (silicone) rubber, moulded over the hose and hose fittings
4 Test temperature
Unless otherwise specified, tests shall be conducted between 15 °C and 32 °C (59 °F and 90 °F).
5 Tests on PTFE inner tubes
5.1 Density and relative density
5.1.1 Principle
The test is intended to control the crystallinity of PTFE inner tubes.
5.1.2 Test methods
The relative density of the PTFE tubing shall be measured in accordance with ISO 7258:1984, method A or
method B. The density of the PTFE tubing shall be measured in accordance with ISO 7258:1984, method C.
5.2 Tensile tests
5.2.1 Principle
This test is intended to determine the mechanical properties of the PTFE tubing.
5.2.2 Test conditions
Test specimens shall be conditioned for at least 2 h at room temperature prior to testing.
5.2.3 Apparatus
5.2.3.1 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 for the force
applied to be 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 %.
2 © ISO 2006 – All rights reserved

5.2.3.2 Micrometer
The micrometer used for measuring flat test specimen thickness shall be capable of exerting a pressure of
25 kPa ± 5 kPa (3,63 psi ± 0,7 psi) on the test specimens, and of measuring the thickness to within
± 0,025 mm (0,001 in).
Dial micrometers exerting either a force of 0,8 ± 0,15 N (0,18 lbf ± 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 lbf ± 0,009 lbf) on a circular foot 3,2 mm (0,125 in) in
diameter conform to the pressure requirement specified above. A micrometer should not be used to measure
the thickness of test specimens narrower in width than the diameter of the foot, unless the contact pressure is
properly adjusted.
5.2.4 Calibration of testing machine
The testing machine shall be calibrated.
If the dynamometer is of the strain-gauge type, the test machine shall be calibrated at one or more forces at
regular intervals.
5.2.5 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 jeweler's hard honing stones. The condition of the die may 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 may 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
5.2.6 Determination of tensile strength and elongation
5.2.6.1 Procedure
Place the test specimens (see 5.2.5) in the jaws of the testing machine (5.2.3.1), 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.
5.2.6.2 Expression of results
2)
Calculate the tensile strength, R , in newtons per square millimetre , using the following equation:
m
F
R =
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.
Calculate the percentage total elongation at fracture, A , using the following equation:
t
⎛⎞
LL−
uo
A=×100
⎜⎟
t
⎜⎟
L
⎝⎠o
where
L is the length measured between the jaws at fracture of the test specimen;
u
L is the original length measured between the jaws before application of force.
o
5.3 Rolling and proof-pressure tests
5.3.1 Principle
This test is intended to check that there are no flaws in the sintered tube.
5.3.2 Rolling test — Procedure
Pass each tube, in a single pass, through six sets of metal rollers so that it is subjected to the sequence of
diametral flexings specified in Table 1; rollers shall be arranged to prevent inadvertent rotation in the tube. It is
assumed that the tube is in a horizontal position and that pressure of the first set of rollers is exerted vertically;
angles given for the final three sets of rollers may be taken as either clockwise or counterclockwise from the
vertical diameter of the tube. Roller angles shall be as specified in Table 1. A tolerance of ± 2° is allowed on
each roller angle. The roller gap dimensions shall not be larger than those specified in Table 2 for each size.
Table 1 — Roller functions and angles
Set of metal rollers Type of action Roller angle
1 Flattening 0°
2 Flattening 90°
3 Rounding 0°
4 Flattening 45°
5 Flattening 135°
6 Rounding 45°
2) 1 N/mm = 1 MPa
4 © ISO 2006 – All rights reserved

3)
Table 2 — Roller gap dimensions
Flattening gap Rounding gap
Hose size
max. max.
Metric part Inch part Class B Class D Class B Class D
10 500 kPa 21 000 kPa 10 500 kPa 21 000 kPa
(1 523 psi) (3 046 psi) (1 523 psi) (3 046 psi)
Equivalent
and lower and higher and lower and higher
outside diameter of tube
nominal pressure nominal pressure nominal pressure nominal pressure
Size Size mm (in) mm (in) mm (in) mm (in) mm (in)
DN05 – 03 4,762 (0,187) 5,2 (0,203) 5,2 (0,203) 5,5 (0,218) 6,4 (0,250)
DN06 – 04 6,350 (0,250) 5,5 (0,218) 7,1 (0,281) 5,5 (0,218) 6,4 (0,250)
DN08 – 05 7,937 (0,312) 5,5 (0,218) — — 6,4 (0,250) — —
DN10 – 06 9,525 (0,375) 5,5 (0,218) 7,1 (0,281) 7,9 (0,312) 8,3 (0,328)
DN12 – 08 12,700 (0,500) 5,9 (0,234) 8,3 (0,328) 9,5 (0,375) 11,9 (0,469)
DN16 – 10 15,875 (0,625) 6,4 (0,250) 8,3 (0,328) 12,7 (0,500) 14,7 (0,578)
DN20 – 12 19,050 (0,750) 6,4 (0,250) 8,3 (0,328) 12,7 (0,500) 17,5 (0,688)
DN25 – 16 25,400 (1,000) 6,4 (0,250) 8,3 (0,328) 19,1 (0,750) 21,0 (0,828)
DN32 – 20 31,750 (1,250) 7,9 (0,312) 11,1 (0,438) 22,2 (0,875) 25,4 (1,000)
DN40 – 24 38,100 (1,500) 9,5 (0,375) — — 31,8 (1,250) — —

5.3.3 Proof-pressure test — Procedure
After the roll test, hold the tube for not less than 2 min. at proof pressures as shown in Table 3, using water or
air as the test medium.
3)
Table 3 — Proof pressure
Hose size Proof pressure
Metric part Inch part Class B Class D Nominal Nominal
10 500 kPa 21 000 kPa pressure pressure
(1 523 psi) (3 046 psi) 10 342 kPa 20 684 kPa
Equivalent
and lower and higher (1 500 psi) (3 000 psi)

outside diameter of tube
and lower and higher
nominal pressure nominal pressure nominal pressure nominal pressure
Size Size mm (in) kPa (psi) kPa (psi) kPa (psi) kPa (psi)
DN05 – 03 4,762 (0,187) 2 690 (390) 3 310 (480) 2 690 (390) 3 310 (480)
DN06 – 04 6,350 (0,250) 2 480 (360) 2 620 (380) 2 480 (360) 2 620 (380)
DN08 – 05 7,937 (0,312) 2 000 (290) — — 2 000 (290) — —
DN10 – 06 9,525 (0,375) 1 590 (230) 1 930 (280) 1 590 (230) 1 930 (280)
DN12 – 08 12,700 (0,500) 1 240 (180) 1 520 (220) 1 240 (180) 1 520 (220)
DN16 – 10 15,875 (0,625) 1 170 (170) 1 170 (170) 1 170 (170) 1 170 (170)
DN20 – 12 19,050 (0,750) 965 (140) 890 (130) 965 (140) 890 (130)
DN25 – 16 25,400 (1,000) 621 (90) 660 (95) 621 (90) 660 (95)
DN32 – 20 31,750 (1,250) 448 65) 660 (95) 448 (65) 660 (95)
DN40 – 24 38,100 (1,500) 310 (45) — — 310 (45) — —

3) Special size high pressure hose assembly callout shall utilize lower hose size value noted.
5.4 Electrical conductivity test
5.4.1 Preconditioning
The test specimen shall be a 350 mm (13,78 in) length of PTFE hose tube (without braid). The inner surface
of the tube shall be washed first with degreasing fluid (test fluid No. 1; see Annex A) and then with isopropyl
alcohol (test fluid No. 2; see Annex A) to remove surface contamination. The inside of the tube shall then be
thoroughly dried at room temperature.
5.4.2 Procedure
Arrange the test specimen vertically as shown in Figure 2. The relative humidity shall be kept below 70 %.
Apply 1 000 V ± 10 V d.c. between the upper and lower electrodes (salt water solution). The salt water
solution shall be a solution of sodium chloride in chemically pure water [ρ (NaCl) = 450 g/l].
− 6
Measure the current with an instrument having a sensitivity of at least 1 µA (= 1 × 10 A).
6 Test on hoses and hose assemblies
6.1 Stress degradation test
6.1.1 Principle
This test is intended to verify that the inner tube of the hose has been sintered and quenched to the proper
crystallinity to eliminate stress cracking or creep with subsequent leakage.
6.1.2 Procedure
6.1.2.1 Fill the hose assemblies with a high-temperature test fluid (test fluid No. 3; see Annex A) and
place in an oven maintained at the maximum working temperature specified in the procurement specification.
Apply to the hose assemblies the nominal pressure specified in the procurement specification, and hold that
pressure for at least 20 h.
Precautions shall be taken to ensure that the hose assemblies do not come into contact with parts of the oven
that are at a higher temperature.
6 © ISO 2006 – All rights reserved

Dimensions in millimetres
Key
1 probe
2 conductor tube
3 vent
4 upper electrode (salt water solution)
5 non-conductive plug
6 O-ring
7 vent (if any)
8 polytetrafluoroethylene (PTFE) (inner tube of the hose)
9 non-conductive container
10 lower electrode (salt water solution)
Figure 2 — Test set-up for electrical conductivity test on inner tubes
6.1.2.2 Gradually release the pressure, remove the assemblies from the oven, drain and cool to room
temperature. Then flush the assemblies with a quantity of fresh high-temperature test fluid (test fluid No. 3;
see Annex A) equivalent in volume to at least twice the volume of the test specimen volume, and drain.
6.1.2.3 Fill the hose assemblies with hydraulic test fluid (test fluid No. 4; see Annex A). Apply to the hose
assemblies the nominal pressure specified in the procurement specification, and hold that pressure for at least
2 h at room temperature.
6.1.2.4 Repeat the procedure specified in 6.1.2.1 to 6.1.2.3 a total of three times.
6.1.2.5 Within 4 h after the final pressurization period of 2 h, drain the hose assemblies, flush them using
a suitable cleaning process and place in an oven for at least 1 h at a temperature of 70 °C ± 5 °C
(158 °F ± 9 °F).
6.1.2.6 Within 8 h after the drying process has been completed, remove the hose assemblies from the
oven, cool to room temperature, and then subject them to a pneumatic effusion (air under water) test. For this
test, install the hose assemblies in a test set-up constructed similarly to that shown in Figure 3.
6.1.2.7 Immerse the test set-up with the hose assemblies installed in water. Apply nominal pressure for at
least 15 min to allow any entrapped air in the hose to escape.
6.1.2.8 Hold the pressure for a further period of 5 min. During this time, collect the gas escaping from the
test specimen, including the juncture of the hose and the fitting, but not including the juncture of the fitting to
the test set-up. After the pressurization period of 5 min, calculate the average rate of effusion through the
hose and two fittings, expressed as millilitres per minute per metre of the hose length.
6.2 Pneumatic effusion test
6.2.1 Principle
This test is intended to show that the inner tube of the hose does not have excessive porosity.
6.2.2 Procedure
Subject the hose assemblies for 1 h
...