ISO 6772:2012

Aerospace - Fluid systems - Impulse testing of hydraulic hose, tubing and fitting assemblies

This International Standard specifies the requirements and the procedures for impulse testing of hose, tubing, and fitting assemblies for use in aerospace hydraulic systems. Requirements may apply, when appropriate, to components used in other aerospace fluid systems.

Aéronautique et espace — Systèmes de fluides — Essai d'impulsion des tuyauteries flexibles, tubes et raccords

General Information

• Status: Published
• Publication Date: 23-Sep-2012
• 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 6 - Couplings for rigid pipe
• Current Stage: 9092 - International Standard to be revised
• Start Date: 19-Nov-2024
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 6772:1988 - Aerospace - Fluid systems - Impulse testing of hydraulic hose, tubing and fitting assemblies
• Effective Date: 30-May-2009

Overview

ISO 6772:2012 specifies requirements and procedures for impulse testing of hose, tubing and fitting assemblies used in aerospace hydraulic (and, where appropriate, other aerospace fluid) systems. The standard provides a repeatable test method to evaluate assembly resistance to hydraulic impulse fatigue and to support qualification and evaluation of components for system use.

The standard emphasizes traceable measurements, controlled pressure-waveform shape and repeatable test sequences to demonstrate long-term reliability under simulated service conditions.

Key Topics

• Impulse trace shape: Dynamic pressure/time traces observed on an oscilloscope must conform to the specified envelope (the shaded area in the standard) and permit assessment of rate-of-rise and peak characteristics.

• Rate of pressure rise: Calculated from the times at 10 % and 90 % of peak pressure using the formula:

  Rate of pressure rise = (0.9·p - 0.1·p) / (t_at_0.9p - t_at_0.1p)

  where p is the peak pressure and t_at_0.9p / t_at_0.1p are the corresponding times.

• Peak pressure and classes: Peak pressures and required minimum/maximum rates of rise are specified by pressure class and nominal diameter in Tables 1 and 2.

• Specimen preparation: Test specimens must follow the component detailed design specification and receive applicable production treatments and production tests prior to impulse testing.

• Test fluid: The test fluid shall be the specified aircraft system fluid or another hydraulic fluid compatible with the component under test.

• Test method and duration: Typical cycle rate is (70 ± 5) cycles/min and, unless otherwise specified, the total number of cycles is 200 000. Oscilloscope sweep and data acquisition must record the impulse trace with accuracy traceable to international standards.

• Temperature and soak: Temperature sequences and soak times are defined (see Table 3); a minimum 1 h soak is required after stabilizing at maximum or minimum temperatures before testing that portion of the sequence.

Applications

ISO 6772:2012 is used by:

• Manufacturers for qualification testing of hydraulic hose assemblies, tubing and fittings.
• Test laboratories validating component endurance against hydraulic impulse fatigue.
• Procurement and design teams to specify standardised impulse-test requirements and acceptance criteria.

Benefits include improved reliability of fluid transmission elements, standardized test reporting, and evidence of fatigue resistance for certification and procurement.

Related Standards

• ISO 6771 - Pressure and temperature classifications (referenced for pressure classes).
• ISO 8575 - Hydraulic system tubing (referenced for nominal outside diameters).
• ISO 8625-1 - Vocabulary for pressure-related terms (definition of peak pressure).
• SAE AIR 1228 - Standard Impulse Machine Equipment and Operation (bibliographic reference).

For implementation, refer directly to ISO 6772:2012 for tables, figures and exact test envelopes and procurement-specific requirements.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 6772
Third edition
2012-10-01
Aerospace — Fluid systems — Impulse
testing of hydraulic hose, tubing and
fitting assemblies
Aéronautique et espace — Systèmes de fluides — Essai d’impulsion
des tuyauteries flexibles, tubes et raccords
Reference number
©
ISO 2012
© ISO 2012
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.
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Tel. + 41 22 749 01 11
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Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 1
4.1 Shape of impulse trace . 1
4.2 Calculation of pressure rise . 2
4.3 Preparation of specimens . 2
4.4 Test fluid . 3
5 Principle of test . 3
6 Test method . 3
7 Intended use. 4
7.1 Standard . 4
7.2 Reference . 4
Bibliography . 6
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 6772 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 6772:1988), which has been technically
revised. The main changes are as follows:
— 3.2: definition has been modified;
— Clause 5: new paragraph has been added;
— Tables 1, 2 and 3 have been modified to cover additional classes J and K.
iv © ISO 2012 – All rights reserved

Introduction
In hydraulic systems, power is transmitted through the hydraulic fluid under pressure with a network of
tubing and hoses, and their attendant fitting assemblies. In order to demonstrate that these transmission
elements are fit for purpose in terms of the prevention of premature failures due to fatigue, it is necessary
to conduct appropriate impulse pressure testing.
This document provides the overall requirements for pressure impulse testing of hydraulic system
distribution elements.
INTERNATIONAL STANDARD ISO 6772:2012(E)
Aerospace — Fluid systems — Impulse testing of hydraulic
hose, tubing and fitting assemblies
1 Scope
This International Standard specifies the requirements and the procedures for impulse testing of hose,
tubing, and fitting assemblies for use in aerospace hydraulic systems. Requirements may apply, when
appropriate, to components used in other aerospace fluid systems.
2 Normative references
The following documents, in whole or
...