ISO 23933:2006

Aerospace — Aramid reinforced lightweight polytetrafluoroethylene (PTFE) hose assemblies, classification 135 degrees C/20 684 kPa (275 degrees F /3 000 psi) and 135 degrees C/21 000 kPa (275 degrees F/3 046 psi) — Procurement specification

ISO 23933:2006 specifies requirements for aramid reinforced lightweight polytetrafluoroethylene (PTFE) hose assemblies for use in aircraft hydraulic, oil and fuel systems at temperatures between -55 °C and 135 °C (-65 °F and 275 °F) and at a nominal pressure of 21 000 kPa (210 bar) (3 046 psi) or 20 684 kPa (3 000 psi). 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.

Aéronautique et espace — Tuyauteries flexibles en polytétrafluoroéthylène (PTFE) renforcement aramide, série légère, classification 135 degrés C/ 20 684 kPa (275 degrés F/3 000 psi) et 135 degrés C/21 000 kPa (275 degrés F/3 046 — Spécification d'approvisionnement

General Information

• Status: Published
• Publication Date: 19-Jan-2006
• ICS: 49.080 - Aerospace fluid systems and components
• 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

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 23933
First edition
2006-01-15
Aerospace — Aramid reinforced
lightweight polytetrafluoroethylene
(PTFE) hose assemblies, classification
135 °C/20 684 kPa (275 °F/3 000 psi) and
135 °C/21 000 kPa (275 °F/3 046 psi) —
Procurement specification
Aéronautique et espace — Tuyauteries flexibles en
polytétrafluoroéthylène (PTFE) renforcement aramide, série légère,
classification 135 °C/20 684 kPa (275 °F/3 000 psi) et
135 °C/21 000 kPa (275 °F/3 046 psi) — Spécification
d'approvisionnement
Reference number
©
ISO 2006
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ii © ISO 2006 – All rights reserved

Contents Page
Foreword. iv
1 Scope.1
2 Normative references.1
3 Classification.2
4 Requirements.2
4.1 Limits of application.2
4.2 Qualification.2
4.3 Materials.2
4.4 Construction.3
4.5 Inner tube requirements.4
4.6 Hose assembly.5
4.7 Fitting threads.6
4.8 Part numbering of interchangeable parts .7
4.9 Identification of products.7
4.10 Workmanship.7
4.11 Hose assembly — Test and performance requirements .8
5 Quality assurance.12
5.1 Responsibility for inspection .12
5.2 Classification of inspections.12
5.3 Qualification inspections .12
5.4 Quality conformance inspections.15
5.5 Test conditions .16
5.6 Inspection methods.17
6 Preparation for delivery .18
6.1 Storage and packaging .18
6.2 Marking.18
7 Ordering data .18
Annex A (informative) Equivalent materials .19
Annex B (informative) Qualification procedures and fire resistance specifications .21
Bibliography .22

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 23933 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 10, Aerospace fluid systems and components.

iv © ISO 2006 – All rights reserved

INTERNATIONAL STANDARD ISO 23933:2006(E)

Aerospace — Aramid reinforced lightweight
polytetrafluoroethylene (PTFE) hose assemblies, classification
135 °C/20 684 kPa (275 °F/3 000 psi) and 135 °C/21 000 kPa
(275 °F/3 046 psi) — Procurement specification
1 Scope
This International Standard specifies requirements for aramid reinforced lightweight polytetrafluoroethylene
(PTFE) hose assemblies for use in aircraft hydraulic, oil and fuel systems at temperatures between − 55 °C
and 135 °C (− 65 °F and 275 °F) and at a nominal pressure of 21 000 kPa (210 bar) (3 046 psi) or 20 684 kPa
(3 000 psi). 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.
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
ISO 2859-1, Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by
acceptance quality limit (AQL) for lot-by-lot inspection
ISO 3161:1999, Aerospace — UNJ threads — General requirements and limit dimensions
ISO 5855-3:1990, Aerospace — MJ threads — Part 3: Limit dimensions for fittings for fluid systems
ISO 6772:1988, Aerospace — Fluid systems — Impulse testing of hydraulic hose, tubing and fitting
assemblies
ISO 7258:1984, Polytetrafluoroethylene (PTFE) tubing for aerospace applications — Methods for the
determination of the density and relative density
ISO 8829-2, Aerospace — Test methods for polytetrafluoroethylene (PTFE) innertube hose assemblies —
Part 2: Non-metallic braid
SAE AS 150, Hose assembly, type classifications of, basic performance and fire resistance
SAE AS 1055, Fire testing of flexible hose, tube assemblies, coils, fittings and similar system components
SAE AS 1241, Fire resistant phosphate ester hydraulic fluid for aircraft
3 Classification
Hose assemblies furnished under this International Standard shall be classified as follows:
⎯ Type A: 20 684 kPa (3 000 psi) nominal pressure;
⎯ Type B: 21 000 kPa (210 bar) (3 046 psi) nominal pressure.
When no classification is specified by reference to this standard, type B shall apply.
4 Requirements
4.1 Limits of application
The use of these hose assemblies in high-pressure pneumatic storage systems is not recommended. 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 International Standard, for example for oxygen, shall be subject
to the approval of the purchaser.
4.2 Qualification
4.2.1 General
Hose assemblies supplied in accordance with this International Standard shall be representative of products
which have been subjected to and which have successfully passed the requirements and tests specified in
this International Standard.
4.2.2 Manufacturer qualification
Manufacturer approval shall be granted by outside agency procedure (see Table B.1, Procedure no. 1).
4.2.3 Product qualification
Product approval shall be granted by outside agency procedure (see Table B.1, Procedure no. 2).
4.3 Materials
4.3.1 General
The hose assembly materials shall be as described in this International Standard. All materials not specifically
described in this International Standard shall be of the highest quality and suitable for the purpose intended.
4.3.2 Metals
Metals used in the fittings shall conform to the applicable specifications described in Table 1 (or equivalent
specifications; see Annex A). Welded and redrawn tubing shall not be used. Material no. 1 shall not be used
for welded assemblies.
2 © ISO 2006 – All rights reserved

Table 1 — Metals to be used in hose assemblies
Material no.
Form Metal
(see Annex A)
Austenitic, annealed or as-rolled, corrosion-resistant steel 1
Austenitic, annealed or as-rolled, stabilized, corrosion-resistant steel 2 and 3
Bars and
forgings
Precipitation-hardening, corrosion-resistant steel 4, 5 and 6
Titanium 6Al-4V 7
CPTi 8
Austenitic, seamless or welded, annealed, corrosion-resistant steel 9
Tubing
Austenitic, seamless or welded, stabilized, corrosion-resistant steel 10 and 11
Cold-worked, stress-relieved titanium alloy 12

4.4 Construction
4.4.1 General
To meet the construction and performance requirements laid down in this International Standard and as
required for its intended use, the hose assembly shall consist of:
⎯ a seamless PTFE inner tube (see 4.4.2);
⎯ treated para-aramid reinforcement (see 4.4.3);
⎯ outer cover or braid protection to meet qualification and usability requirements;
⎯ corrosion-resistant steel and/or titanium end-fittings (see 4.4.4).
4.4.2 Inner tube
The inner tube shall be of a seamless construction of virgin PTFE resin of uniform gauge. It shall have a
smooth bore and shall be free from pitting or projections on the inner surface. Additives may be included in the
compound from which the tube is extruded with no more than 3 % of such additives being retained in the
mixture.
4.4.3 Reinforcement
The reinforcement shall consist of a treated para-aramid braid and an outer braid or other coverage to protect
the para-aramid.
The reinforcement shall be arranged on the outside surface of the inner tube so as to provide sufficient
strength to ensure compliance with the requirements laid down in this International Standard. Broken,
damaged, slack or missing reinforcement yarn shall be cause for rejection.
The outer cover, or braid, shall provide 100 % coverage to protect the para-aramid reinforcement from
exposure to ultraviolet light when bending to minimum radius specified in Table 4.
A continuous lay line which can be interrupted with hose manufacturer’s name or trademark, shall be
permanently marked in contrasting colour along the hose length.
4.4.4 Fittings
4.4.4.1 General
It shall be proven that all fittings comply with the requirements laid down in this Internati
...