ISO 10785:2011

Space systems — Bellows — Design and operation

ISO 10785:2011 specifies general and detailed requirements for bellows used in space systems. It establishes requirements with regard to material, design, analysis, fabrication, material, testing, inspection and operation for space use. ISO 10785:2011 is applicable to metallic bellows which are used as pressure bearing components and are integrated into a pressure system. ISO 10785:2011 is not applicable to engine bellows or valve bellows.

Systèmes spatiaux — Souffleries — Conception et fonctionnement

General Information

• Status: Published
• Publication Date: 26-Sep-2011
• ICS: 49.140 - Space systems and operations
• Technical Committee: ISO/TC 20/SC 14 - Space systems and operations
• Drafting Committee: ISO/TC 20/SC 14/WG 1 - Design engineering and production
• Current Stage: 9092 - International Standard to be revised
• Completion Date: 24-Aug-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 10785
First edition
2011-10-01
Space systems — Bellows — Design
and operation
Systèmes spatiaux — Souffleries — Conception et fonctionnement
Reference number
ISO 10785:2011(E)
©
ISO 2011

---------------------- Page: 1 ----------------------
ISO 10785:2011(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2011
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.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 10785:2011(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 5
5 Requirements . 5
5.1 General . 5
5.2 Design requirements . 6
5.3 Material requirements . 8
5.4 Fabrication and process control requirements . 9
5.5 Quality assurance requirements . 9
5.6 Operation and maintenance requirements .10
5.7 Specific qualification test requirements .12
Annex A (informative) Design safety factors .14
© ISO 2011 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 10785:2011(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.
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 10785 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 14, Space systems and operations.
iv © ISO 2011 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 10785:2011(E)
Introduction
The bellows for space systems is usually used under severe conditions, such as high pressure, extremely
low temperatures, large deflection, or high inner flow speed. The design safety factor of the bellows tends
to be small in order to satisfy two different function requirements simultaneously. One is the function of the
pressure bearing component, which all pressure components have, and the other is the special function to
accommodate installation misalignment, thermal expansion or contraction and displacement induced by large
deformation of the pressurized propellant tank.
There are many items to be considered for design and manufacture such as hoop stress, bulging stress,
buckling strength, flow-induced vibration, and cyclic deflection.
This International Standard establishes general and specific requirements for bellows in order to provide safe
and reliable bellows hardware and operations.
Some examples of the design safety factors are shown in Annex A at the end of this International Standard.
© ISO 2011 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 10785:2011(E)
Space systems — Bellows — Design and operation
1 Scope
This International Standard specifies general and detailed requirements for bellows used in space systems. It
establishes requirements with regard to material, design, analysis, fabrication, material, testing, inspection and
operation for space use.
This International Standard is applicable to metallic bellows which are used as pressure bearing components
and are integrated into a pressure system. This International Standard is not applicable to engine bellows or
valve bellows.
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 14623:2003, Space systems — Pressure vessels and pressurized structures — Design and operation
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acceptance test
required formal test conducted on flight hardware to ascertain that the materials, manufacturing processes and
workmanship meet specifications and that the hardware is acceptable for intended usage
3.2
bellows
corrugated single-layer or multi-layer elastic casing, when integrated into a duct assembly, capable of performing
linear, shear and angular movements
NOTE 1 A bellows consists of both a convolution section and a mechanical linkage section, which serves as a bellows
restraint. The most common mechanical linkage types are gimbal-type and braided-type. In some cases a bellows contains
an internal liner or flow tube for the purpose of improving flow capability.
NOTE 2 See Figure 1.
3.3
bellows stiffness
ratio between an applied force and the resulting bellows displacement
3.4
burst pressure
pressure level at which rupture or unstable fracture of the pressurized hardware item occurs
3.5
bulging stress
meridional or axial stress at the convolution section induced by pressure
© ISO 2011 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO 10785:2011(E)
1
Key
1 internal pressure
Figure 1 — Bellows
3.6
component
functional unit that is viewed as an entity for the purpose of analysis, manufacturing, maintenance, or record keeping
NOTE Adapted from ISO 14623:2003.
3.7
critical condition
most severe environmental condition in terms of loads, deflection, pressures and temperatures, or combination
thereof, imposed on systems, subsystems, structures and components during service life
[ISO 14623:2003, definition 2.12]
3.8
deflection
contraction or expansion along its longitudinal axis, angular rotation, or lateral offset
NOTE See Figure 2.
1
2
Key
1 axial deflection
2 angular rotation
Figure 2 — Deflection
2 © ISO 2011 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 10785:2011(E)
3.9
design burst factor
multiplying factor applied to maximum expected operating pressure (MEOP) or maximum design pressure
(MDP) [3.20] to obtain the design burst pressure
3.10
design burst pressure
differential pressure that pressurized hardware must withstand without bursting in the applicable
operational environment
NOTE Design burst pressure is equal to the product of the MEOP or MDP and a design burst factor.
[ISO 14623:2003, definition 2.16]
3.11
design safety factor
design factor of safety
factor of safety
multiplying factor to be applied to the limit load and/or maximum expected operating pressure (MEOP) or
maximum design pressure (MDP) [3.20]
[ISO 14623:2003, definition 2.17]
3.12
detrimental deformation
structural deformation, deflection or displacement that prevents any portion of the structure or other system
from performing its intended function or that jeopardizes mission success
NOTE Adapted from ISO 14623:2003, definition 2.19.
3.13
fatigue
process of progressive localized permanent structural change occurring in a material/structure subjected to
conditions which produce fluctuating stresses and strains at some point or points and which may culminate in
cracks or complete fracture after a sufficient number of fluctuations
[ISO 14623:2003, definition 2.23]
3.14
fatigue life
number of cycles of stress or strain of a specified character that a given structure or component of a structural
assembly can sustain (without the presence of flaws) before failure of a specified nature occurs
NOTE Adapted from ISO 14623:2003, definition 2.24.
3.15
fracture
type of failure mode in a material/structure which is generally preceded by a large amount of plastic deformation
3.16
flaw
local discontinuity in a structural material
EXAMPLES Crack, cut, scratch, void, delamination disbond, impact damage and other kinds of mechanical damage.
NOTE Adapted from ISO 14623:2003, definition 2.25.
3.17
hoop stress
circumferential stress at the convolution section induced by pressure
© ISO 2011 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 10785:2011(E)
3.18
leak-before-burst
LBB
design concept which shows that at maximum expected operating pressure (MEOP) [3.20] potentially critical
flaws will grow through the wall of a metallic pressurized hardware item and cause pressure relieving leakage
rather than burst or rupture (catastrophic failure)
NOTE Adapted from ISO 14623:2003, definition 2.35.
3.19
limit load
maximum expected load, or combination of loads, which a structure or a component in a structural assembly is
expected to experience during its service life, in association with the applicable operating environments
NOTE 1 Load is a generic term for thermal load, pressure, external mechanical load (force, moment, or enforced
displacement) or internal mechanical load (residual stress, pretension, or inertial load).
NOTE 2 The corresponding stress or strain is called limit stress or limit strain.
NOTE 3 Limit load is sometimes referred to as design limit load.
NOTE 4 Adapted from ISO 14623:2003, definition 2.36.
3.20
maximum expected operating pressure
MEOP
highest differential pressure which a pressurized hardware item is expected to experience during its service life
and retain its functionality, in association with its applicable operating environments
NOTE 1 MEOP includes the effects of temperature, transient peaks, relief pressures, regulator pressure, vehicle
acceleration, phase changes, transient pressure excursions, and relief valve tolerance.
NOTE 2 Some projects may replace MEOP with maximum design pressure (MDP), which takes into account more
conservative conditions.
NOTE 3 Adapted from ISO 14623:2003, definition 2.41.
3.21
mechanical linkage section
section within bellows assembly that will serve as the bellows restraint for thrust force by pressure, deflection,
or other factors
3.22
personnel’s approach
action or state of a ground crew approach when near to the bellows or another component while the component
is pressurized
3.23
proof factor
multiplying factor applied to the limit load or maximum expected operating pressure (MEOP) or maximum
design pressure (MDP) [3.20] to obtain proof load or proof pressure for use in acceptance testing
[ISO 14623:2003, definition 2.50]
3.24
proof test pressure
pressure level used to give evidence of satisfactory workmanship and material quality and/or establish maximum
initial flaw sizes for safe-life demonstration
4 © ISO 2011 – All rights reserved

---------------------- Page: 9 ----------------------
ISO 10785:2011(E)
3.25
qualification test
required formal contractual tests conducted at load levels and durations in order to demonstrate that the
design, manufacturing, and assembly of flight-quality structures have resulted in hardware that conforms to
specification requirements
NOTE In addition, the qualification test may validate the planned acceptance programme, including test techniques,
procedures, equipment, instrumentation, and software.
3.26
repair
action on a nonconforming product to make it acceptable for the intended use
NOTE 1 Repair includes remedial action taken on previously conforming product to restore it for use, for example as
part of maintenance.
NOTE 2 Unlike rework, repair can affect or change parts of the nonconforming product.
3.27
refurbishment
renovation and restoration to intended use condition
3.28
service life
period of time (or number of cycles) that starts with the manufacturing of the pressurized hardware and continues
through all acceptance testing, handling, storage, transportation, launch operations, orbital operations,
refurbishment, re-testing, re-entry or recovery from orbit, and reuse that may be required or specified for the item
[ISO 14623:2003, definition 2.57]
3.29
work hardening effect
effect of strengthening material by plastic deformation
NOTE The representative material is 300 series corrosion-resistant steel.
4 Abbreviated terms
LBB leak-before-burst
MDP maximum design pressure
MEOP maximum expected operating pressure
NDI non-destructive inspection
QA quality assurance
S-N stress versus number of cycles to failure
NOTE Plots of S-N data are used in the fatigue test.
5 Requirements
5.1 General
Clause 5 presents the requirements for design, stress analysis, material selection and characterization,
fabrication and process control, and quality assurance, as well as operational requirements including
maintenance, repair, refurbishment and storage for bellows in a pressure system.
© ISO 2011 – All rights reserved 5

---------------------- Page: 10 ----------------------
ISO 10785:2011(E)
Safety requirements such as the design safety factor and safety measures in operation should comply with
appropriate facility/agency requirements. Examples of design safety factor are shown in Annex A.
5.2 Design requirements
5.2.1 Loads, pressures, and environments
The anticipated pressure-temperature-deflection history and other associated environments throughout
the service life of bellows in a pressure system shall be determined in accordance with specified mission
requirements, also including flight ultimate conditions.
The fundamental parameters or conditions in loads, pressures, and environments for bellows are
considered as follows:
a) internal/external pressure;
b) temperature;
c) fluid (working medium);
d) flow velocity;
e) deflection;
f) pre-loads;
g) life-cycle;
h) vibration, shock, acceleration;
i) externally applied installation loads;
j) handling loads.
NOTE Give additional specific requirements for pre-loads, such as minimizing pre-loads, if it is not possible to
estimate pre-loads by measuring misalignment of adjacent structures before and after mounting the bellows, taking into
account the acceptable rigidity of each part, which are suitably arranged.
5.2.2 Strength
The bellows in a pressure system shall possess sufficient strength to withstand MEOP and maximum deflection,
or other additional loads in the expected operating environments throughout the service life. It shall sustain
proof test pressure without experiencing leakage and incurring detrimental deformation. It shall also withstand
design burst pressure without experiencing rupture or collapse.
The bellows design safety factor is described in Annex A.
5.2.3 Stiffness
There are various types of deflection that the bellows can accommodate. These are axial deflection, angular
rotation, lateral offset, torsion, etc. The spring rate of the bellows for each direction shall comply with system
requirements to withstand maximum expected load to the adjacent members and maximum expected vibration
modes of the system.
Bellows with a linkage mechanism shall possess adequate axial stiffness against pressure to preclude
excessive load to the adjacent members.
Bellows stiffness is a part of design and shall be analysed and, if necessary, verified by testing.
6 © ISO 2011 – All rights reserved

---------------------- Page: 11 ----------------------
ISO 10785:2011(E)
5.2.4 Thermal effects
The design of the bellows shall consider the following thermal effects, as appropriate:
a) temperature;
b) thermal gradients;
c) thermal stresses and deformations;
d) changes in the physical and mechanical properties of the materials of construction; and
e) thermal cycle.
5.2.5 Stress analysis
5.2.5.1 General
A detailed and comprehensive stress analysis of each new design of the bellows shall be conducted to
demonstrate acceptable stress levels. For the convolution section, the following stresses shall be evaluated
using reliable analyses methods:
a) hoop stress by pressure;
b) bulging stress by pressure; and
c) bending stress by deflection.
A detailed and comprehensive buckling stability analysis shall be conducted using a reliable analysis method.
A detailed analysis of the linkage strength shall be performed to demonstrate the pressure separating load of
the bellows and to prevent unacceptable axial deformation.
The spring rate of the bellows for axial deflection, angular rotation, lateral offset, and torsion shall be calculated
accounting for deformation of convolutions and restraints of
...