ISO 24638:2021
(Main)Space systems — Pressure components and pressure system integration
Space systems — Pressure components and pressure system integration
This document establishes the baseline requirements for the design, fabrication and testing of space flight pressure components. It also establishes the requirements for the assembly, installation, test, inspection, operation and maintenance of the pressure systems in spacecraft and launch vehicles. These requirements, when implemented on a particular space system, ensure a high level of confidence in achieving safe and reliable operation. This document applies to all pressure components other than pressure vessels and pressurized structures in a pressure system. It covers lines, fittings, valves, bellows, hoses and other appropriate components that are integrated to form a pressure system. The requirements for pressure vessels and pressurized structures are set forth in ISO 14623. This document does not apply to engine components.
Systèmes spatiaux — Intégration des composants sous pression et des systèmes sous pression
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INTERNATIONAL ISO
STANDARD 24638
Second edition
2021-05
Space systems — Pressure
components and pressure system
integration
Systèmes spatiaux — Intégration des composants sous pression et des
systèmes sous pression
Reference number
ISO 24638:2021(E)
©
ISO 2021
---------------------- Page: 1 ----------------------
ISO 24638:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 24638:2021(E)
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 5
5 General requirements . 5
5.1 General . 5
5.2 Design requirements . 6
5.2.1 Loads, pressures and environments . 6
5.2.2 Strength . 6
5.2.3 Stiffness . 6
5.2.4 Thermal effects . 7
5.2.5 Stress analysis . 7
5.2.6 Fatigue analysis/damage tolerance (safe-life) analysis . 7
5.2.7 Analysis of survivability against space debris and meteoroid impacts . 7
5.2.8 Avoidance of accidental break-up caused by an on-board source of energy . 7
5.3 Material requirements. 8
5.3.1 Metallic materials . 8
5.3.2 Non-metallic material requirements . 8
5.4 Fabrication and process requirements . 8
5.5 Contamination control and cleanliness requirements . 9
5.5.1 General contamination control requirements . 9
5.5.2 Design considerations . 9
5.6 Quality assurance programme requirements .10
5.6.1 General.10
5.6.2 QA programme inspection plan requirements .10
5.6.3 QA inspection technique requirements .10
5.6.4 QA inspection data requirements .10
5.6.5 Acceptance test requirements .10
5.7 Qualification test requirements.11
5.8 Operation and maintenance requirements .11
5.8.1 Operating procedure .11
5.8.2 Safe operating limits .11
5.8.3 Inspection and maintenance .12
5.8.4 Repair and refurbishment .12
5.8.5 Storage .12
5.8.6 Documentation .12
5.8.7 Reactivation .13
5.8.8 Recertification .13
6 General pressurized-system requirements .13
6.1 System analysis requirements .13
6.1.1 System pressure analysis .13
6.1.2 System functional analysis .13
6.1.3 System hazard analysis.14
6.2 Design features .14
6.2.1 Assembly .14
6.2.2 Routing .14
6.2.3 Separation .14
6.2.4 Shielding.14
6.2.5 Grounding .15
6.2.6 Handling .15
© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 24638:2021(E)
6.2.7 Special tools .15
6.2.8 Test points .15
6.2.9 Common-plug test connectors .15
6.2.10 Individual test connectors .15
6.2.11 Threaded parts .15
6.2.12 Friction-type locking devices .15
6.2.13 Internally threaded bosses .15
6.2.14 Retainer or snap rings .15
6.2.15 Snubbers .15
6.3 Component selection .16
6.3.1 Connections .16
6.3.2 Fluid temperature .16
6.3.3 Actuator pressure rating .16
6.3.4 Pressure rating .16
6.3.5 Pump selection .16
6.3.6 Fracture and leakage .16
6.3.7 Oxygen system components.16
6.3.8 Pressure regulators .16
6.3.9 Manual valves and regulators .16
6.4 Design pressures .17
6.4.1 Overpressure or underpressure .17
6.4.2 Back-pressure .17
6.4.3 Pressure isolation .17
6.4.4 Gas/fluid separation .17
6.4.5 Compressed-gas bleeding .17
6.5 Mechanical-environment design .17
6.5.1 Acceleration and shock loads .17
6.5.2 Torque loads .17
6.5.3 Vibration loads .17
6.6 Controls .17
6.6.1 Interlocks . .17
6.6.2 Multiple safety-critical functions .18
6.6.3 Critical flows and pressures .18
6.7 Protection .18
6.8 Electrical .18
6.8.1 Hazardous atmospheres .18
6.8.2 Radio frequency energy .18
6.8.3 Grounding .18
6.8.4 Solenoids.18
6.8.5 Electric motor-driven pumps .18
6.9 Pressure relief .18
6.9.1 General requirements .18
6.9.2 Flow capacity .19
6.9.3 Sizing .19
6.9.4 Unmanned flight vehicle servicing .19
6.9.5 Automatic relief .19
6.9.6 Venting .19
6.9.7 Relief valve isolation .19
6.9.8 Negative-pressure protection .19
6.9.9 Reservoir pressure relief .20
6.9.10 Air pressure control .20
6.10 Control devices .20
6.10.1 Directional control valves .20
6.10.2 Overtravel .20
6.10.3 Pressure and volume control stops .20
6.10.4 Manually operated levers .20
6.11 Accumulators.20
6.11.1 Accumulator design . .20
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 24638:2021(E)
6.11.2 Accumulator gas pressure gauges .21
6.11.3 Accumulator identification .21
6.12 Flexible hose .21
6.12.1 Installation .21
6.12.2 Restraining devices .21
6.12.3 Flexible hose stress .21
6.12.4 Temporary installations .21
7 Specific pressure system requirements .21
7.1 General .21
7.2 Hydraulic systems .22
7.2.1 Hydraulic system components .22
7.2.2 Pressure limit .23
7.2.3 Cavitations .23
7.2.4 Hydraulic lockup .23
7.2.5 Pressure relief .23
7.3 Pneumatic-system requirements .24
7.3.1 Pneumatic-system components .24
7.3.2 Controls .24
Annex A (informative) Recommended minimum safety factors.25
Annex B (informative) Open line force calculation factors .26
Bibliography .27
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 24638:2021(E)
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 24638:2008), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— 6.8.4 was revised to make the requirement a more general statement;
— corrections were made to Tables 1 and A.1.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
vi © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 24638:2021(E)
Introduction
Space vehicles and their launch systems usually have a series of engines to use for both primary
propulsion and secondary propulsion functions, such as attitude control and spin control.
Different engines have different propellant feed systems. For example, the gas-pressure feed system
is typically used for liquid propellant engines; it consists of a high-pressure gas tank, a fuel tank and
an oxidizer tank, valves and a pressure regulator. All these components are referred to as pressurized
hardware.
Due to their specific usage, the liquid propellant tanks and the high-pressure gas bottles are often
referred to as pressure vessels, while valves, regulators and feed lines are usually called pressure
components.
ISO 14623 sets forth the standard requirements for pressure vessels in order to achieve safe operation
and mission success. However, the requirements for pressure components are not covered in ISO 14623.
Furthermore, the standard requirements for pressure system integration are lacking.
Significant work has been done in the area of design, analysis and testing of pressure components for
use in space systems. This document establishes the preferred methods for these techniques and sets
forth the requirements for the assembly, installation, test, inspection, operation and maintenance of the
pressure systems in spacecraft and launch vehicles.
© ISO 2021 – All rights reserved vii
---------------------- Page: 7 ----------------------
INTERNATIONAL STANDARD ISO 24638:2021(E)
Space systems — Pressure components and pressure
system integration
1 Scope
This document establishes the baseline requirements for the design, fabrication and testing of space
flight pressure components. It also establishes the requirements for the assembly, installation, test,
inspection, operation and maintenance of the pressure systems in spacecraft and launch vehicles.
These requirements, when implemented on a particular space system, ensure a high level of confidence
in achieving safe and reliable operation.
This document applies to all pressure components other than pressure vessels and pressurized
structures in a pressure system. It covers lines, fittings, valves, bellows, hoses and other appropriate
components that are integrated to form a pressure system.
The requirements for pre
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 24638
ISO/TC 20/SC 14
Space systems — Pressure
Secretariat: ANSI
components and pressure system
Voting begins on:
20210201 integration
Voting terminates on:
Systèmes spatiaux — Intégration des composants sous pression et des
20210329
systèmes sous pression
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/FDIS 24638:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 24638:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 24638:2021(E)
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 5
5 General requirements . 5
5.1 General . 5
5.2 Design requirements . 6
5.2.1 Loads, pressures and environments . 6
5.2.2 Strength . 6
5.2.3 Stiffness . 6
5.2.4 Thermal effects . 6
5.2.5 Stress analysis . 7
5.2.6 Fatigue analysis/damage tolerance (safe-life) analysis . 7
5.2.7 Analysis of survivability against space debris and meteoroid impacts . 7
5.2.8 Avoidance of accidental break-up caused by an on-board source of energy . 7
5.3 Material requirements. 8
5.3.1 Metallic materials . 8
5.3.2 Non-metallic material requirements . 8
5.4 Fabrication and process requirements . 8
5.5 Contamination control and cleanliness requirements . 9
5.5.1 General contamination control requirements . 9
5.5.2 Design considerations . 9
5.6 Quality assurance programme requirements . 9
5.6.1 General. 9
5.6.2 QA programme inspection plan requirements .10
5.6.3 QA inspection technique requirements .10
5.6.4 QA inspection data requirements .10
5.6.5 Acceptance test requirements .10
5.7 Qualification test requirements.11
5.8 Operation and maintenance requirements .11
5.8.1 Operating procedure .11
5.8.2 Safe operating limits .11
5.8.3 Inspection and maintenance .12
5.8.4 Repair and refurbishment .12
5.8.5 Storage .12
5.8.6 Documentation .12
5.8.7 Reactivation .12
5.8.8 Recertification .13
6 General pressurized-system requirements .13
6.1 System analysis requirements .13
6.1.1 System pressure analysis .13
6.1.2 System functional analysis .13
6.1.3 System hazard analysis.14
6.2 Design features .14
6.2.1 Assembly .14
6.2.2 Routing .14
6.2.3 Separation .14
6.2.4 Shielding.14
6.2.5 Grounding .14
6.2.6 Handling .15
© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 24638:2021(E)
6.2.7 Special tools .15
6.2.8 Test points .15
6.2.9 Commonplug test connectors .15
6.2.10 Individual test connectors .15
6.2.11 Threaded parts .15
6.2.12 Friction-type locking devices .15
6.2.13 Internally threaded bosses .15
6.2.14 Retainer or snap rings .15
6.2.15 Snubbers .15
6.3 Component selection .16
6.3.1 Connections .16
6.3.2 Fluid temperature .16
6.3.3 Actuator pressure rating .16
6.3.4 Pressure rating .16
6.3.5 Pump selection .16
6.3.6 Fracture and leakage .16
6.3.7 Oxygen system components.16
6.3.8 Pressure regulators .16
6.3.9 Manual valves and regulators .16
6.4 Design pressures .17
6.4.1 Overpressure or underpressure .17
6.4.2 Backpressure .17
6.4.3 Pressure isolation .17
6.4.4 Gas/fluid separation .17
6.4.5 Compressedgas bleeding .17
6.5 Mechanicalenvironment design .17
6.5.1 Acceleration and shock loads .17
6.5.2 Torque loads .17
6.5.3 Vibration loads .17
6.6 Controls .17
6.6.1 Interlocks . .17
6.6.2 Multiple safety-critical functions .18
6.6.3 Critical flows and pressures .18
6.7 Protection .18
6.8 Electrical .18
6.8.1 Hazardous atmospheres .18
6.8.2 Radio frequency energy .18
6.8.3 Grounding .18
6.8.4 Solenoids.18
6.8.5 Electric motordriven pumps .18
6.9 Pressure relief .18
6.9.1 General requirements .18
6.9.2 Flow capacity .19
6.9.3 Sizing .19
6.9.4 Unmanned flight vehicle servicing .19
6.9.5 Automatic relief .19
6.9.6 Venting .19
6.9.7 Relief valve isolation .19
6.9.8 Negativepressure protection .19
6.9.9 Reservoir pressure relief .20
6.9.10 Air pressure control .20
6.10 Control devices .20
6.10.1 Directional control valves .20
6.10.2 Overtravel .20
6.10.3 Pressure and volume control stops .20
6.10.4 Manually operated levers .20
6.11 Accumulators.20
6.11.1 Accumulator design . .20
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 24638:2021(E)
6.11.2 Accumulator gas pressure gauges .20
6.11.3 Accumulator identification .21
6.12 Flexhose .21
6.12.1 Installation .21
6.12.2 Restraining devices .21
6.12.3 Flexhose stress .21
6.12.4 Temporary installations .21
7 Specific pressure system requirements .21
7.1 General .21
7.2 Hydraulic systems .21
7.2.1 Hydraulic system components .21
7.2.2 Pressure limit .22
7.2.3 Cavitations .23
7.2.4 Hydraulic lockup .23
7.2.5 Pressure relief .23
7.3 Pneumatic-system requirements .24
7.3.1 Pneumatic-system components .24
7.3.2 Controls .24
Annex A (informative) Recommended minimum safety factors.25
Annex B (informative) Open line force calculation factors .26
Bibliography .27
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/FDIS 24638:2021(E)
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 nongovernmental, 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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 24638:2008), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— 6.8.4 was revised to make the requirement a more general statement;
— corrections were made to Tables 1 and A.1.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
vi © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/FDIS 24638:2021(E)
Introduction
Space vehicles and their launch systems usually have a series of engines to use for both primary
propulsion and secondary propulsion functions, such as attitude control and spin control.
Different engines have different propellant feed systems. For example, the gas-pressure feed system
is typically used for liquid propellant engines; it consists of a high-pressure gas tank, a fuel tank and
an oxidizer tank, valves and a pressure regulator. All these components are referred to as pressurized
hardware.
Due to their specific usage, the liquid propellant tanks and the high-pressure gas bottles are often
referred to as pressure vessels, while valves, regulators and feed lines are usually called pressure
components.
ISO 14623 sets forth the standard requirements for pressure vessels in order to achieve safe operation
and mission success. However, the requirements for pressure components are not covered in ISO 14623.
Furthermore, the standard requirements for pressure system integration are lacking.
Significant work has been done in the area of design, analysis and testing of pressure components for
use in space systems. This document establishes the preferred methods for these techniques and sets
forth the requirements for the assembly, installation, test, inspection, operation and maintenance of the
pressure systems in spacecraft and launch vehicles.
© ISO 2021 – All rights reserved vii
---------------------- Page: 7 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 24638:2021(E)
Space systems — Pressure components and pressure
system integration
1 Scope
This document establishes the baseline requirements for the design, fabrication and testi
...
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