ISO 7314:2002

Aerospace - Fluid systems - Metal hose assemblies

ISO 7314 gives specifications for medium pressure, high temperature, flexible metal hose assemblies suitable for continuous operation in liquid and pneumatic systems from - 55 °C to + 400 °C, with short duration excursions up to + 650 °C. The hose assemblies covered by this International Standard are intended for use in aerospace applications for conveying air and other gases in pneumatic systems, bleed air systems, heating and ventilating systems and instrument air systems. ISO 7314 does not cover flow velocity in such assemblies exceeding 54 m/s; higher velocities require special vibration-dampening devices. Hose assemblies supplied to the specifications laid down in this International Standard may be of two types: Type 1: Convoluted inner tube - welded, of moderate mass and moderate flexibility. Type 2: Convoluted inner tube - seamless or butt-welded and redrawn, of low mass and high flexibility.

Aéronautique et espace — Systèmes de fluides — Tuyauteries flexibles métalliques

General Information

• Status: Published
• Publication Date: 14-Nov-2002
• 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: 9092 - International Standard to be revised
• Start Date: 12-Dec-2025
• Completion Date: 27-Dec-2025

Relations

• Consolidated By: ISO 10993-9:2009 - Biological evaluation of medical devices - Part 9: Framework for identification and quantification of potential degradation products
• Effective Date: 06-Jun-2022
• Revises: ISO 7314:1994 - Aerospace - Fluid systems - Hose assembly, metal
• Effective Date: 15-Apr-2008

Overview

ISO 7314:2002 - "Aerospace - Fluid systems - Metal hose assemblies" defines requirements for medium‑pressure, high‑temperature flexible metal hose assemblies used in aerospace fluid systems. It covers hoses for conveying air and other gases in pneumatic, bleed‑air, heating/ventilating and instrument‑air systems for continuous service from −55 °C to +400 °C with short excursions up to +650 °C. The standard limits flow velocity to 54 m/s (higher velocities require special damping) and specifies two construction types: Type 1 (welded convoluted inner tube - moderate mass/flexibility) and Type 2 (seamless or butt‑welded/redrawn convoluted inner tube - low mass/high flexibility).

Key topics and technical requirements

• Materials and construction: Inner tube, braid and end fittings are made from stabilized austenitic stainless steel; materials must be defect‑free and suitable for the specified temperature range.
• Hose types: Type 1 (welded inner tube) and Type 2 (seamless or redrawn/butt‑welded inner tube). Type 2 assemblies may substitute for Type 1 without further approval; the reverse requires customer consent.
• End fittings and joints: End‑fittings are welded to the hose; welds must be fusion welds compatible with the base material. Fitting masses and configuration are controlled.
• Heat treatment: Where stress relief is required, weld joints shall be stress‑relieved at 895 °C ±15 °C for 2 h ±15 min to ensure corrosion and embrittlement resistance.
• Dimensions, pressure and bend radius: Tables in the standard (Tables 2–4) define nominal diameters, operating/proof/burst pressure ratings (with temperature correction factors), and minimum static/dynamic bend radii.
• Performance & qualification tests: Mandatory qualification and production tests include:
  • Visual/examination and dimensional checks
  • Proof pressure and burst tests
  • Corrosion (salt‑spray/immersion) tests
  • Vibration and braid integrity tests
  • Flexure/pressure cycling (50,000 cycles)
  • Repeated torque (fitment) tests
  • Cold and thermal‑shock tests
  • Stress‑corrosion (Strauss) tests
• Quality assurance: Supplier and user responsibilities, inspection classification, test methods and preparation for delivery (closures, packaging, marking).

Applications

ISO 7314 is intended for aerospace applications requiring reliable metal flexible hoses where high temperature, medium pressure and long life under vibration/flexure are critical. Typical uses:

• Pneumatic and instrument air systems
• Bleed air ducting
• Environmental control/heating and ventilation lines
• Any gas‑conveying service in aircraft/space vehicles within the stated limits

Who should use ISO 7314

• Aerospace hose manufacturers and fabricators
• Design and systems engineers specifying fluid/system components
• Procurement teams and suppliers verifying compliance
• Quality, test and certification engineers responsible for qualification and acceptance testing

Related standards

• Normative reference: ISO 8625‑1 (Aerospace fluid systems vocabulary - general terms and definitions). Consult product drawings and applicable contractual documents for interfacing requirements.

Keywords: ISO 7314, metal hose assemblies, aerospace fluid systems, flexible metal hose, high temperature hose, hose qualification, braid reinforcement, proof pressure, burst test, bend radius.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 7314
Third edition
2002-11-01
Aerospace — Fluid systems — Metal hose
assemblies
Aéronautique et espace — Systèmes de fluides — Tuyauteries flexibles
métalliques
Reference number
©
ISO 2002
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ii © ISO 2002 – All rights reserved

Contents Page
Foreword . iv
1 Scope. 1
2 Normative reference. 1
3 Terms and definitions. 1
4 Requirements . 1
4.1 Qualification. 1
4.2 Materials. 2
4.3 Design and construction . 2
4.4 Dimensions, masses and ratings . 4
4.5 Performance . 5
4.6 Part numbering of interchangeable parts. 6
4.7 Product identification . 7
4.8 Workmanship. 7
5 Quality assurance provisions . 7
5.1 Supplier’s responsibility. 7
5.2 User’s responsibility. 8
5.3 Classification of inspections . 8
5.4 Test methods . 12
6 Preparation for delivery. 17
6.1 Closures . 17
6.2 Packaging . 17
6.3 Marking of containers. 17
Bibliography. 18

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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7314 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 10,
Aerospace fluid systems and components.
This third edition cancels and replaces the second edition (ISO 7314:1994), which has been technically revised.
iv © ISO 2002 – All rights reserved

INTERNATIONAL STANDARD ISO 7314:2002(E)

Aerospace — Fluid systems — Metal hose assemblies
1 Scope
This International Standard gives specifications for medium pressure, high temperature, flexible metal hose
assemblies suitable for continuous operation in liquid and pneumatic systems from − 55 °C to + 400 °C, with short
duration excursions up to + 650 °C.
The hose assemblies covered by this International Standard are intended for use in aerospace applications for
conveying air and other gases in pneumatic systems, bleed air systems, heating and ventilating systems and
instrument air systems when used at pressures and temperatures within the limits laid down in Tables 2 and 3. This
International Standard does not cover flow velocity in such assemblies exceeding 54 m/s; higher velocities require
special vibration-dampening devices.
Hose assemblies supplied to the specifications laid down in this International Standard may be of two types:
 Type 1: Convoluted inner tube – welded, of moderate mass and moderate flexibility.
 Type 2: Convoluted inner tube – seamless or butt-welded and redrawn, of low mass and high flexibility.
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent edition of the normative document indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 8625-1:1993, Aerospace — Fluid systems — Vocabulary — Part 1: General terms and definitions related to
pressure
3 Terms and definitions
For the purposes of this International Standard, the terms and definitions given in ISO 8625-1 apply.
4 Requirements
4.1 Qualification
Any hose assembly supplied to the specifications laid down in this International Standard shall be a product that,
concerning hose construction and end-fitting attachment method, is identical to specimens that have been tested
and that have passed the qualification tests specified in clause 5.
Qualified hose assemblies of type 2 construction may be automatically substituted for type 1 hoses, but type 1
hoses may not be substituted for type 2 hoses unless customer approval is given.
4.2 Materials
The hose assembly materials shall be uniform in quality, free from defects and suitable for use in continuous
ambient and/or fluid temperatures ranging from − 55 °C to + 400 °C with short fluid temperature excursions up to
650 °C. The materials shall be consistent with good manufacturing practices and shall conform to the applicable
specifications and the requirements specified in this International Standard.
4.3 Design and construction
4.3.1 General
The hose assembly shall consist of a convoluted, stabilized, pressure-carrying tube, in corrosion-resistant steel,
suitable for the intended use, and uniform in size and wall thickness. The hose assembly shall be reinforced with
stabilized corrosion-resistant steel braided wire and shall have stabilized corrosion-resistant steel end fittings and
nuts. End fittings shall be attached to the hose by welding. The end-fitting outlet design shall mate with applicable
end fittings.
4.3.2 End fittings
The hose-to-fitting joint shall be welded in a suitable manner in order to meet the requirements specified in this
International Standard. It is recommended that fitting joints be kept to a minimum so as to reduce potential leakage
paths. The mass of type 2 fittings shall not exceed the values given in Table 1. Type 1 fitting masses shall be as
given on the approved drawing.
Table 1 — Masses for type 2 hose assemblies with standard 37° or 24° fittings
Maximum masses
Hose nominal size
Hose Standard end fittings
g
DN g/cm Straight 45° elbow 90° elbow
05 1,5 20 20 20
06 2 23 23 23
08 2,5 27 29 29
10 3 32 36 36
12 4,2 55 59 64
16 5,3 82 91 100
20 6,5 163 177 186
25 9 218 259 291
32 12 358 413 449
40 19 486 507 552
50 24 768 810 845
63 35 – – –
4.3.3 Hose
4.3.3.1 Inner tube construction
In the case of type 1 hoses, the inner tube shall be an annular or helical, convoluted flexible tube made from
welded, stabilized austenitic stainless steel.
2 © ISO 2002 – All rights reserved

In the case of type 2 hoses, the inner tube shall be an annular, convoluted flexible tube of seamless or butt-welded
and redrawn construction using stabilized austenitic stainless steel.
For either type, the inner tube shall be uniform in size and quality, and free from pitting and other defects.
There shall be no inner tube splices on hose assemblies shorter than or equal to 1 m in length. One splice is
allowed for each additional metre of hose assembly length. Splices are undesirable, but, if required, shall be low-
profile welds in accordance with 4.3.4 and Figure 1. After welding, the convolutions shall be closed as shown in
Figure 1.
Key
1 Convoluted metal hose inner tube
2 Fusion weld
3 High-temperature braze alloy
a
Maximum 5 l.
b
Normal convolution spacing specified by supplier design.
Figure 1 — Inner tube splice configuration
4.3.3.2 Reinforcement
The reinforcement shall be a suitably braided construction using stabilized austenitic stainless steel wire in such a
manner as to meet the requirements specified in this International Standard. There shall be no splices, missing
loops, kinks or broken wires in the braid wire reinforcement.
4.3.4 Welds
All welds shall be fusion welds suitable for the intended use. Filler wire, if required, shall be compatible with the
weld material used. Equivalent supplier or other comparable welding specifications may be substituted subject to
prior approval by the purchaser.
4.3.5 Heat treatment
If stress-relieving of austenitic stainless steel welds is required in order to meet corrosion and embrittlement
resistance, the joints shall be stress-relieved at 895 °C ± 15 °C for 2 h ± 15 min.
4.4 Dimensions, masses and ratings
4.4.1 Hose diameter
The inside diameter of the convoluted hose and the outside diameter of the braid covering shall be as given in
Table 2.
Table 2 — Dimensions and performance requirements for hose assemblies
Hose
Fitting Operating pressure Proof pressure Proof pressure
Hose
a b b b
Inside Outside
Bore at 20 °C at 20 °C at 20 °C
nominal
diameter diameter
min. max. min. min.
size
min. max.
DN
mm mm mm kPa bar kPa bar kPa bar
03 2 6 2 13 750 138 20 650 207 55 150 552
04 3 7 2,5 13 750 138 20 650 207 55 150 552
05 4 9,9 3 13 750 138 20 650 207 55 150 552
5,5 13 3,5 13 750 138 20 650 207 55 150 552
08 7 15 5 12 000 120 18 000 180 48 000 480
10 8,5 18 6,4 11 000 110 16 500 165 44 000 440
12 11 20,5 9,1 9 600 96 14 500 145 38 600 386
14 27 11,6 8 300 83 12 400 124 33 000 330
20 17,5 31,5 14,4 7 200 72 10 700 107 29 000 290
25 23 38 19,3 5 500 55 8 300 83 22 000 220
32 30 47 23,4 3 800 38 5 700 57 15 200 152
36 57 32 3 000 30 4 500 45 12 000 120
50 48 70 42 2 400 24 3 600 36 9 600 96
63 60 85 55 1 800 18 2 700 27 7 200 72
a
For ball check diameter see 4.4.2.
b
For pressure requirements at elevated temperature, multiply the value by the factor given in Table 3.

Table 3 — Factor for correcting pressure requirements at elevated temperature (see Table 2)
Material Austenitic chrome/nickel steel stabilized for carbide precipitation
Operating temperature, °C 20 50 100 150 200 250 300 350 400 450 500 550 600 650
Correction factor 1 0,91 0,84 0,78 0,73 0,69 0,65 0,62 0,6 0,58 0,57 0,57 0,56 0,55

4.4.2 Assembly internal diameter
When bent to the appropriate minimum static bend radius as specified in Table 4, 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 Table 2. When elbow fitting is used, the
diameter of the sphere shall be 85 % of the appropriate minimum internal diameter of the end fittings as specified in
Table 2, to accept some elbow ovality.
4 © ISO 2002 – All rights reserved

4.4.3 Bend radius
The requirements for the minimum bend radius of hoses shall be as given in Table 4. The bend radius shall be
measured to the centreline of the hose.
Table 4 — Minimum centreline bend radius
Minimum bend radius
mm
Hose nominal size
DN Type 1 hose assembly Type 2 hose assembly
a
Static Dynamic Static Dynamic
100 200 – –
04 100 200 – –
05 100 200 50 100
06 100 200 50 100
08 125 250 65 130
10 150 300 75 150
12 175 350 100 200
16 200 400 115 230
20 235 470 125 250
25 310 620 150 300
32 370 740 175 350
40 450 900 225 450
50 550 1 100 275 550
63 700 1 400 350 700
a
No flexure in service.
4.4.4 Assembly length
Hose assembly lengths shall be as specified on the applicable product standard or drawing.
4.4.5 Masses
Maximum masses of type 2 hose assemblies, with standard 37 ° or 24 ° fittings, shall be as given in Table 1.
Maximum masses for type 1 hose assemblies and for type 2 hose assemblies with other fittings shall be as
stipulated on the supplier’s drawing when presented to the purchaser for approval.
4.5 Performance
4.5.1 General
The hose assembly operating proof and burst pressure ratings and minimum bend radius, as given in Tables 2
and 4 respectively, shall be verified by proving that the performance requirements of 4.5.2 to 4.5.9 are met or
exceeded, through qualification testing as specified in clause 5. Compliance with performance requirements shall
be maintained by adherence to the quality assurance provisions specified in clause 5.
4.5.2 Examination of product
Each assembly shall conform dimensionally and materially to the applicable product standard or drawing and to all
requirements of this International Standard when examined in accordance with 5.4.1.
4.5.3 Proof pressure test
The hose assembly shall withstand the applicable proof pressure, specified in Table 2, at room temperature (i.e. at
20 °C) without leakage or evidence of any permanent deformation or malfunction that would affect hose assembly
installation, removal or use when tested in accordance with 5.4.2.
4.5.4 Corrosion test
The hose assembly shall be capable of withstanding the proof pressure requirements specified in 4.5.3 after
50 immersion cycles in a 35 g/l sodium chloride (NaCl) solution in accordance with 5.4.3.
4.5.5 Vibration test
The hose assembly shall have no broken braid wire and shall be capable of withstanding, without leakage, the
proof pressure requirements specified in 4.5.3, after vibration testing in accordance with 5.4.4.
4.5.6 Flexure/pressure cycling endurance test
The hose assembly shall have no broken braid wire and shall be capable of withstanding the proof pressure
requirements specified in 4.5.3, after 50 000 combination flexure/pressure cycles in accordance with 5.4.5.
4.5.7 Repeated torque test
The hose assembly end fitting shall be capable of sealing and withstanding the proof pressure requirements
specified in 4.5.3, after 15 installations on a mating fitting in accordance with 5.4.6. The fitting nut shall be free
enough to permit turning on the elbow or insertion by hand.
4.5.8 Cold test
The hose assembly shall show no evidence of leakage when tested in accordance with 5.4.7.
4.5.9 Thermal shock test
The hose assembly shall show no evidence of leakage when tested in accordance
...