SIST EN 16603-31-02:2018

SLOVENSKI STANDARD
01-november-2018
1DGRPHãþD
SIST EN 16603-31-02:2015
Vesoljska tehnika - Oprema za dvofazni toplotni transport
Space engineering - Two-phase heat transport equipment
Raumfahrttechnik - Ausrüstung für Zwei-Phasen-Wärmetransport
Ingénierie spatiale - Equipements de transfert de chaleur à deux phases
Ta slovenski standard je istoveten z: EN 16603-31-02:2018
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 16603-31-02
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2018
ICS 49.140
Supersedes EN 16603-31-02:2015
English version
Space engineering - Two-phase heat transport equipment
Ingénierie spatiale - Equipements de transfert de Raumfahrttechnik - Ausrüstung für Zwei-Phasen-
chaleur à deux phases Wärmetransport
This European Standard was approved by CEN on 11 July 2018.

CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical
references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to
any CEN and CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN and CENELEC member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2018 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. EN 16603-31-02:2018 E
reserved worldwide for CEN national Members and for
CENELEC Members.
Table of contents
European Foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms defined in other standards . 9
3.2 Terms specific to the present standard . 10
3.3 Abbreviated terms. 13
4 TPHTE verification principles . 15
4.1 TPHTE categorization . 15
4.2 Involved organizations . 15
4.3 Generic requirements in this standard . 16
4.4 TPHTE qualification principles . 17
4.4.1 Processes, number of qualification units . 17
4.4.2 Thermal and mechanical qualification . 17
4.5 TPHTE acceptance principles . 21
5 Requirements for qualification activity . 22
5.1 Technical specification (TS) . 22
5.1.1 General . 22
5.1.2 Requirements to the TS . 22
5.1.3 Requirements for formulating technical requirements . 23
5.2 Materials, parts and processes . 23
5.3 General qualification requirements . 24
5.3.1 Qualification process . 24
5.3.2 Supporting infrastructure – Tools and test equipment . 24
5.4 Qualification process selection . 24
5.5 Qualification stage . 26
5.5.1 Qualification requirements . 26
5.5.2 Quality audits . 27
5.5.3 Qualification methods . 27
5.5.4 Full and delta qualification programme . 29
5.5.5 Performance requirements . 29
5.6 Qualification test programme . 32
5.6.1 Number of qualification units . 32
5.6.2 Test sequence . 32
5.6.3 Test requirements . 35
5.6.4 Physical properties measurement . 38
5.6.5 Proof pressure test . 39
5.6.6 Pressure cycle test . 39
5.6.7 Burst pressure test . 39
5.6.8 Leak test . 40
5.6.9 Thermal performance test . 41
5.6.10 Mechanical tests . 43
5.6.11 Thermal cycle test . 45
5.6.12 Aging and life tests . 45
5.6.13 Gas plug test . 46
5.6.14 Reduced thermal performance test . 46
5.7 Operating procedures . 47
5.8 Storage . 47
5.9 Documentation . 47
5.9.1 Documentation summary . 47
5.9.2 Specific documentation requirements. 47
6 Requirements for acceptance activity . 50
6.1 General . 50
6.2 Acceptance process . 50
6.2.1 Materials, parts and processes. 50
6.2.2 General acceptance requirements . 50
6.2.3 Supporting infrastructure – Tools and test equipment . 51
6.2.4 Acceptance test programme . 51
6.2.5 Operating procedures . 51
6.2.6 Storage . 51
6.2.7 Documentation . 52
Bibliography . 53

Figures
Figure 3-1: Tilt definition for HP . 12
Figure 3-2: Tilt definition for LHP . 12
Figure 4-1: Categories of TPHTE (two-phase heat transport equipment) . 16
Figure 4-2: Figure-of-merit (G) for some TPHTE fluids . 18
Figure 4-3: Definition of temperature and performance ranges for a HP . 19
Figure 5-1: Selection of qualification process . 26
Figure 5-2: Qualification test sequence for HP . 33
Figure 5-3: Qualification test sequence for CDL . 34

Tables
Table 4-1: Examples of allowed design modifications for acceptance hardware . 21
Table 5-1: Categories of two-phase heat transport equipment according to heritage
(adapted from ECSS-E-ST-10-02C, Table 5-1) . 24
Table 5-2: Allowable tolerances . 36
Table 5-3: Measurement accuracy . 38
Table 5-4: Equipment resonance search test levels . 44
Table 5-5: Sinusoidal vibration qualification test levels . 44
Table 5-6: Random vibration qualification test levels . 45
Table 5-7: TPHTE documentation . 49

European Foreword
This document (EN 16603-31-02:2018) has been prepared by Technical
Committee CEN-CENELEC/TC 5 “Space”, the secretariat of which is held by
DIN.
This standard (EN 16603-31-02:2018) originates from ECSS-E-ST-31-02C Rev.1.
This document supersedes EN 16603-31-02:2015.
The main changes with respect to EN 16603-31-02:2015 are listed below:
• Implementation of Change Requests
• Clause 3 Terms, definition and abbreviated terms" updated and
Nomenclature added
• Titles of clauses 4, 5, 5.1, 5.5.1; updated
• Clause 4 updated to include TPHTE acceptance requirements in new
clause 4.5 "TPHTE acceptance principles"
• Merge of former clauses 4.4 and 4.5 to new clause 4.4 "TPHTE
qualification principles"
• DRDs in Annex A to H deleted. Requirements calling the DRDs updated
to the DRD in the dedicated ECSS Standard
This European Standard shall be given the status of a national standard, either
by publication of an identical text or by endorsement, at the latest by March
2019, and conflicting national standards shall be withdrawn at the latest by
March 2019.
Attention is drawn to the possibility that some of the elements of this document
may be the subject of patent rights. CEN shall not be held responsible for
identifying any or all such patent rights.
This document has been prepared under a standardization request given to
CEN by the European Commission and the European Free Trade Association.
This document has been developed to cover specifically space systems and has
therefore precedence over any EN covering the same scope but with a wider
domain of applicability (e.g. : aerospace).
According to the CEN-CENELEC Internal Regulations, the national standards
organizations of the following countries are bound to implement this European
Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Introduction
This Standard replaces ESA PSS-49, Issue 2 “Heat pipe qualification
requirements”, written in 1983, when the need for heat pipes in several ESA
projects had been identified. At that time a number of European development
activities were initiated to provide qualified heat pipes for these programmes,
which culminated in a first heat pipe application on a European spacecraft in
1981 (MARECS, BR-200, ESA Achievements - More Than Thirty Years of
Pioneering Space Activity, ESA November 30, 2001), followed by a first major
application on a European communication satellite in 1987 (TV-SAT 1, German
Communication Satellites).
ESA PSS-49 was published at a time, when knowledge of heat pipe technology
started to evolve from work of a few laboratories in Europe (IKE, University
Stuttgart, EURATOM Research Centre, Ispra). Several wick designs, material
combinations and heat carrier fluids were investigated and many process
related issues remained to be solved. From today’s view point the qualification
requirements of ESA PSS-49 appear therefore very detailed, exhaustive and in
some cases disproportionate in an effort to cover any not yet fully understood
phenomena. As examples the specified number of qualification units (14), the
number of required thermal cycles (800) and the extensive mechanical testing
(50 g constant acceleration, high level sine and random vibration) can be cited.
The present Standard takes advantage of valid requirements of ESA PSS-49, but
reflects at the same time today’s advanced knowledge of two-phase cooling
technology, which can be found with European manufacturers. This includes
experience to select proven material combinations, reliable wick and container
designs, to apply well-established manufacturing and testing processes, and
develop reliable analysis tools to predict in-orbit performance of flight
hardware. The experience is also based on numerous successful two-phase
cooling system applications in European spacecraft over the last 20 years.
Besides streamlining the ESA PSS-49, to arrive at today’s accepted set of heat
pipe qualification requirements, the following features have also been taken
into account:
• Extension of PSS-49 heat pipe qualification requirements to include heat
pipe acceptance requirements;
• Inclusion of qualification and acceptance requirements for two-phase
loops (CPL, LHP);
• Reference to applicable requirements in other ECSS documents;
• Formatting to recent ECSS template in order to produce a document,
which can be used in business agreements between customer and
supplier.
Scope
This standard defines qualification and acceptance requirements for two-phase
heat transportation equipment (TPHTE), for use in spacecraft thermal control.
This standard is applicable to qualification and acceptance activities of new
hardware.
However, acceptance requirements of this Standard can be used for existing
hardware, which has been qualified previously to other requirements than
listed herein.
Requirements for mechanical pump driven loops (MPDL) are not included in
the present version of this Standard.
This standard also includes definitions and part of the requirements of ECSS-E-
ST-32-02 applicable to TPHTE qualification and acceptance.
This standard may be tailored for the specific characteristics and constraints of a
space project in conformance with ECSS-S-ST-00.
Normative references
The following normative documents contain provisions which, through
reference in this text, constitute provisions of this ECSS Standard. For dated
references, subsequent amendments to, or revision of any of these publications
do not apply. However, parties to agreements based on this ECSS Standard are
encouraged to investigate the possibility of applying the more recent editions of
the normative documents indicated below. For undated references, the latest
edition of the publication referred to applies.

EN reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS system - Glossary of terms
EN 16603-10-02 ECSS-E-ST-10-02 Space engineering - Verification
EN 16603-10-03 ECSS-E-ST-10-03 Space engineering - Testing
EN 16603-10-06 ECSS-E-ST-10-06 Space engineering - Technical requirements
specification
EN 16603-31 ECSS-E-ST-31 Space engineering - Thermal control general
requirements
EN 16603-32 ECSS-E-ST-32 Space engineering - Structural general requirements
EN 16603-32-01 ECSS-E-ST-32-01 Space engineering- Fracture control
EN 16603-32-02 ECSS-E-ST-32-02 Space engineering - Structural design and
verification of pressurized hardware
EN 16602-70 ECSS-Q-ST-70 Space product assurance - Materials, mechanical
parts and processes
EN 9100:2009 Aerospace series - Quality management systems -
Requirements for Aviation, Space and Defense
Organizations
Terms, definitions and abbreviated terms
3.1 Terms defined in other standards
a. For the purpose of this Standard, the terms and definitions from ECSS-E-
ST-00-01 apply, and in particular the following:
1. acceptance
2. certification
3. component
4. customer
5. equipment
6. product assurance
7. qualification
8. supplier
b. For the purpose of this standard, the following terms and definitions
from ECSS-E-ST-10-02 apply:
1. acceptance stage
2. analysis
3. inspection
4. qualification stage
5. review-of-design (ROD)
6. test
c. For the purpose of this standard, the following terms and definitions
from ECSS-E-ST-32-02 apply:
1. burst pressure
2. internal pressure
3. leak-before-burst (LBB)
4. pressure vessel (PV)
5. pressurized hardware (PH)
6. proof test
3.2 Terms specific to the present standard
3.2.1 capillary driven loop (CDL)
TPL in which fluid circulation is accomplished by capillary action
NOTE See TPL definition in 3.2.21.
3.2.2 capillary pumped loop (CPL)
CDL with the fluid reservoir separated from the evaporator and without a
capillary link to the evaporator
NOTE See CDL definition in 3.2.1.
3.2.3 constant conductance heat pipe (CCHP)
heat pipe with a fixed thermal conductance between evaporator and condenser
at a given saturation temperature
NOTE See heat pipe definition in 3.2.7.
3.2.4 dry-out
depletion of liquid in the evaporator section at high heat input when the
capillary pressure gain becomes lower than the pressure drop in the circulating
fluid
3.2.5 effective length
heat pipe length between middle of evaporator and middle of condenser for
configurations with one evaporator and one condenser only
NOTE Used to determine the heat pipe transport
capability (see 3.2.10).
3.2.6 exposure temperature range
maximum temperature range to which a TPHTE is exposed during its product
life cycle and which is relevant for thermo-mechanical qualification
NOTE 1 The internal pressure at the maximum temperature
of this range defines the MDP for the pressure
vessel qualification of a TPHTE.
NOTE 2 The extreme temperatures of this range can be
below freezing or above critical temperatures of
the working fluid.
NOTE 3 In other technical domains, this temperature range
is typically called non-operating temperature
range (see clause 4 for additional explanation).
3.2.7 heat pipe (HP)
TPHTE consisting of a single container with liquid and vapour passages
arranged in such a way that the two fluid phases move in counter flow
NOTE 1 See TPHTE definition in 3.2.20.
NOTE 2 The capillary structure in a heat pipe extends over
the entire container length.
3.2.8 heat pipe diode (HPD)
heat pipe which transports heat based on evaporation and condensation only in
one direction
NOTE See heat pipe definition in 3.2.7.
3.2.9 loop heat pipe (LHP)
CDL with the fluid reservoir as integral part of the evaporator
NOTE 1 See CDL definition in 3.2.1.
NOTE 2 The reservoir can be separated, but has a capillary
link to the evaporator.
3.2.10 heat transport capability
maximum amount of heat, which can be transported in a TPHTE from the
evaporator to the condenser
NOTE For heat pipes it is the maximum heat load
expressed in [Wm] (transported heat times
effective length).
3.2.11 maximum design pressure (MDP)
maximum allowed pressure inside a TPHTE during product life cycle
3.2.12 mechanical pump driven loop (MPDL)
TPL in which fluid circulation is accomplished by a mechanical pump
NOTE See TPL definitions in 3.2.21.
3.2.13 product life cycle
product life starting from the delivery of the TPHTE hardware until end of
service live
NOTE The product life cycle starts after acceptance of
the product for flight.
3.2.14 reflux mode
operational mode where the liquid is returned from the condenser to the
evaporator by gravitational forces and not by capillary forces
3.2.15 start-up
operational phase starting with initial supply of heat to the evaporator until
nominal operating conditions of the device are established
3.2.16 sub-cooling
temperature difference between average CDL reservoir temperature and the
temperature of the liquid line at the inlet to the reservoir
NOTE The average CDL reservoir temperature
represents the saturation temperature inside the
reservoir.
3.2.17 thermal performance temperature range
temperature range for which a TPHTE is thermally qualified
NOTE In the thermal performance temperature range
a thermal performance map exists.
3.2.18 tilt for HP
height of the evaporator above the condenser during ground testing
NOTE 1 This definition is valid for a configuration with one
evaporator and one condenser (see Figure 3-1).
NOTE 2 The tilt is measured from the highest point to the
lowest point in Figure 3-1.
evaporator
condenser
Figure 3-1: Tilt definition for HP
3.2.19 tilt for LHP
height of the evaporator above the reservoir during ground testing
NOTE 1 See Figure 3-2.
NOTE 2 The tilt is measured from the highest point of the
evaporator to the lowest point of the condenser in
Figure 3-2.
Figure 3-2: Tilt definition for LHP
3.2.20 two-phase heat transport equipment (TPHTE)
hermetically closed system filled with a working fluid and transporting thermal
energy by a continuous evaporation and condensation process using the latent
heat of the fluid
NOTE 1 A fluid evaporates in the heat input zone
(evaporator) and condenses in the heat output
zone (condenser).
NOTE 2 This is in contrast to a single-phase loop where the
sensible heat of a liquid is transported (a liquid
heats up in the heat input zone and cools down in
the heat output zone).
3.2.21 two-phase loop (TPL)
TPHTE with physically separated vapour and liquid transport lines forming a
closed loop
NOTE See TPHTE definition in 3.2.20.
3.2.22 variable conductance heat pipe (VCHP)
heat pipe with an additional non-condensable gas reservoir allowing a variable
thermal conductance between evaporator and condenser
NOTE 1 See heat pipe definition in 3.2.7.
NOTE 2 The variation in thermal conductance is generally
accomplished by regulating the volume of a non-
condensable gas plug reaching into the condenser
zone, which in turn varies the effective condenser
length.
NOTE 3 The variation of the gas volume can be performed
by active or passive means.
3.3 Abbreviated terms
For the purpose of this Standard, the abbreviated terms from ECSS-S-ST-00-01
and the following apply:
Abbreviation Meaning
constant conductance heat pipe
CCHP
capillary driven loop
CDL
capillary pumped loop
CPL
coefficient of thermal expansion
CTE
document requirements definition
DRD
heat pipe
HP
heat pipe diode
HPD
leak before burst
LBB
loop heat pipe
LHP
maximum design pressure
MDP
mechanical pump driven loop
MPDL
metallic special pressurized equipment
MSPE
non-destructive inspection
NDI
pressurized hardware
PH
review-of-design
ROD
Qmax maximum heat transport capability
Abbreviation Meaning
special pressurized equipment
SPE
thermal control (sub)system
TCS
two-phase heat transport equipment
TPHTE
two-phase loop
TPL
technical requirement specification
TS
variable conductance heat pipe
VCHP
verification plan
VP
TPHTE verification principles
4.1 TPHTE categorization
TPHTE as defined in 3.2.20 of this Standard are considered ‘special
pressurized equipment’ (SPE), as per definition of ECSS-E-ST-32-02.
Requirements of ECSS-E-ST-32-02 are included in this Standard for this reason.
The TPHTE are categorized in Figure 4-1 according to their design and
functional principle.
HP’s, LHP’s and CPL’s are categorized as MSPE (Metallic Special Pressurized
Equipment) as described in section 4.1.2 ECSS-E-ST-32-02
Heat pipes consist of a single container with a capillary structure extending
over the entire container length. Liquid and vapour passages are arranged in
such a way that the two fluid phases move in counter flow.
Capillary driven loops (CDL) have separate evaporator and condenser sections,
which are connected by dedicated vapour and liquid tubing. At least one
capillary structure is located in the evaporator section, which serves as capillary
pump to circulate the fluid in a true loop configuration.
The mechanically pumped two-phase loop (MPDL) has a configuration, which
is similar to the CDL, except that the circulation of the fluid is accomplished by
a mechanical pump.
NOTE Requirements for MPDL are not included in the
present version of this Standard.
4.2 Involved organizations
The verification process of TPHTE is generally carried out by a specialized
equipment manufacturer (called in this document “supplier”) and controlled by
the verification authority (called in this document the “customer”).
The verification activity is embedded in the supplier’s product assurance and
quality organization and in most cases the supplier's quality assurance plan has
been established and approved for space activities independently from the
TPHTE verification process specified in this document. It is the task of the
supplier’s PA authority to introduce and approve adequate product assurance
provisions at his subcontractor(s). The existence of an approved PA Plan is
precondition for commencing verification activities.
Figure 4-1: Categories of TPHTE (two-phase heat transport equipment)
4.3 Generic requirements in this standard
The present document provides generic, i.e. not project specific requirements
for formal verification of TPHTE. It is therefore important to select overall and
enveloping verification requirements in order to support a maximum of
spacecraft application without the need for delta verification.
4.4 TPHTE qualification principles
4.4.1 Processes, number of qualification units
The qualification of TPHTE is based on validated manufacturing processes (e.g.
cleaning, surface treatment, welding and leak testing) and covers in general the
following areas:
• Performance over long operation time (compatibility between fluid and
wall material, space radiation, leak tightness)
• Mechanical performance (strength, pressurized hardware)
• Thermal performance (e.g. heat transport capability, start-up behaviour,
heat transfer coefficients)
In this context the number of TPHTE units to be produced for the qualification
program are evaluated and selected by the supplier. There are no general
applicable sources, which specify the minimum of units to be used to undergo
identical qualification testing in order to achieve a successful qualified product.
The question to be answered for each TPHTE configuration is: how many
identical units need to be built and tested in order to validate the production
process.
The following are possible selection criteria:
• Experience of the manufacturer in production of similar products,
• Simplicity of the configuration,
• TPHTE design features, which have inherent capability for good
repeatability of the production processes (e.g. simple axial grooved heat
pipes).
This Standard specifies the number of needed identical pieces of equipment (i.e.
coming from the same batch) submitted to the qualification process.
Compared to full qualification of a new product the number of units can be
reduced for delta qualification of an existing but modified product. (see Table
5-1 for details).
4.4.2 Thermal and mechanical qualification
4.4.2.1 Temperature range
In contrast to most of electronic equipment, the performance of a TPHTE varies
with its operating temperature, because properties of the used heat carrier are
temperature dependent. For heat pipes as an example, important fluid
properties can be grouped into a figure-of-merit (G), which is the product of
surface tension, heat of vaporization and liquid density divided by the liquid
viscosity (for more information see references in Bibliography). G is plotted for
some fluids over the temperature in Figure 4-2. The heat transport capability of
a capillary pumped loop is proportional to these curves.
Figure 4-2: Figure-of-merit (G) for some TPHTE fluids
Generally, the applicable temperature range of a TPHTE is subdivided into a
thermally and a mechanically relevant regime.
The thermal performance temperature range, which is used for thermal
qualification, is defined within the theoretical operating temperature range,
confined by the freezing and the critical temperature of the used fluid. Lower
and upper temperature limits of the qualification range are selected in such a
way that a useful map of thermal performance data can be established. Within
this range the maximum transport capability for qualification is determined.
For a specific space application the operating temperature range (within the
thermal performance temperature range) and the maximum required heat
transport capability are specified.
For thermo-mechanical qualification the temperature range, to which the device
is exposed to during the life cycle, is relevant. In most cases this exposure
temperature range is wider than the mentioned thermal performance
temperature range. The minimum temperature of this range can be below the
freezing temperature of the used heat carrier and it is important to take into
account possible damage caused by the freezing or thawing effects. The upper
exposure temperature can be even above the critical temperature of the heat
carrier. This temperature determines in general the maximum internal pressure
for design and qualification of the device.
The mentioned temperature ranges and associated heat transport capabilities
are illustrated in Figure 4-3.

Legend
Q Maximum transport capability for qualification
max,qual
Q Maximum transport capability for acceptance (specified for a specific project)
max,acc
T , T Freezing and critical temperature of a selected fluid
F C
T T Minimum and maximum performance temperature
P, min, P, max
T T Minimum and maximum acceptance temperature (specified for a specific project)
Ac, min, Ac, max
T P,min  T P,max Performance temperature range
T Ac,min  T Ac,max Acceptance temperature range (specified for a specific project)
Figure 4-3: Definition of temperature and performance ranges for a HP
4.4.2.2 Mechanical qualification
TPHTE are classified as Metallic Special Pressurized Equipment (MSPE) and
relevant mechanical requirements are specified in ECSS-ST-E-32-02 and are
applied in the present Standard for all TPHTE types.
For qualification of a TPHTE as pressurized component, the main characteristic
is the internal pressure, which varies in relation to the exposure temperature of
the unit (temperature dependent saturation pressure of the heat carrier liquid).
ECSS-ST-E-32-02 specifies qualification requirements for heat pipes (see figure
4.12 and Table 4-8 of ECSS-E-ST-32-02). The present Standard selects
qualification requirements for TPHTE, which have seen proof pressure tests ≥
1,5 MDP. Testing is the preferred method rather than qualification by fracture
control analysis.
For qualifying a TPHTE with respect to external mechanical environment the
following mechanical tests are considered:
• Constant or static acceleration
• Sine vibration
• Random vibration
For these tests the qualification unit needs to be rigidly mounted to the test
equipment (vibration table). However, such mounting provisions can have only
reduced similarity to real applications in spacecraft and the meaningfulness of
such tests is, therefore, very often reason for discussion under experts. For heat
pipes it is common understanding not to perform these tests on long heat pipe
profiles for the following reasons:
• The length of the test heat pipe is adapted to the test equipment and is
therefore shorter as in many realistic spacecraft applications.
• The application of heat pipe is often for embedding them in sandwich
structures. Mechanical loads for these applications are quite different as
can be simulated with a rigidly fixed single heat pipe profile.
• Several capillary structures, in particular axial groove heat pipes, are
quite insensitive to mechanical loads and tests as suggested in existing
procedures can be unnecessary.
For many TPHTE applications (in particular for devices with simple capillary
structures, e.g. axial grooves) the formal mechanical qualification can be
therefore performed with the first structural model on satellite level. In case the
risk for such a late qualification is high, pre-qualification can be performed on
unit or part level in particular for the following cases:
• The TPHTE, in particular a heat pipe, has a capillary structure, which is
sensitive towards mechanical loads, e.g. arterial wick. In such a case a
short piece of the heat pipe profile is selected for mechanical qualification
testing (sine, random vibration).
• An evaporator of a LHP or CPL can be separately tested (sine, random
vibration) to verify that mechanical requirements are met.
• Equally this can be true for a two-phase loop condenser, in particular for
configurations where the condenser tubing is embedded into a structural
panel.
Therefore the Standard does not specify at which model level vibration testing
is performed. The supplier and customer are asked to agree on a logical
qualification plan, which can include testing at higher than equipment level.
4.5 TPHTE acceptance principles
The acceptance process demonstrates that the already qualified product is free
of workmanship errors and is ready for subsequent operational use.
Verification is performed by inspection and testing and includes:
• Material conformity (for example inspection of certificates, proof
pressure, leak check)
• Inspection of dimensions and flatness
• Thermal performance check
The design of hardware submitted to the acceptance procedure has been
previously qualified. However, some application driven design modifications
can be accepted as long as the following qualification relevant design features
are not compromised:
• Material selection and compatibility
• Pressurized component
• Thermal performance
Some examples are given in Table 4-1.
It is good practice to perform a similarity analysis to determine that the
hardware, submitted to the acceptance process, is of qualified design.
Table 4-1: Examples of allowed design modifications for acceptance hardware
Qualification relevant Mandatory design feature for Allowed design modification
design feature acceptance hardware for acceptance hardware
Material selection and Wall material and fluid No exception
compatibility combination;
Operating temperatures
Pressurized component Minimum wall thickness and Attachment design (configuration
inner diameter of evaporator, of external flanges);
fluid lines, condenser;
For HP: Length, bend radius larger
Operating temperatures than qualified one;
For CPL: Length of evaporator and
reservoir
Thermal performance Capillary structure Length, number and distribution of
evaporator and condenser zones in
CCHP
Length of fluid and condenser lines
in TPL
Requirements for qualification activity
5.1 Technical specification (TS)
5.1.1 General
a. The qualification process shall be based on a technical specification,
approved by the customer.
NOTE Usually the technical specification evolves from
the functional requirements of the customer
and defines the technical performances for the
proposed solution as part of a business
agreement.
b. The technical specification specified in 5.1.1a shall be written in
accordance with DRD in ECSS-E-ST-10-06 Annex A.
5.1.2 Requirements to the TS
a. The specification shall be identifiable, referable and related to a TPHTE
product.
b. The following entity shall be responsible for the TS:
1. the supplier for a generic TPHTE specification, which is not related
to a specific application;
2. the customer for a specific TPHTE specification, which is related to
a specific application.
NOTE A delta qualification can be necessary, if the
generic specification does not completely meet
the requirements for a specific application.
c. For technical requirements organization, requirements 7.2.3b to 7.2.3e of
ECSS-E-ST-10-06 shall apply.
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g. For technical reference, requirement 7.2.4a of ECSS-E-ST-10-06 shall
apply.
h. For configuration management, requirement 7.2.5a of ECSS-E-ST-10-06
shall apply.
i. Quantity of units required for the qualification process shall be specified
in the TS.
j. For restriction to requirement specification, requirement 7.2.8a of ECSS-
E-ST-10-06 shall apply.
5.1.3 Requirements for formulating technical
requirements
a. For performance specification, requirement 8.2.1a of ECSS-E-ST-10-06
shall apply.
b. To avoid ambiguity in a specification, requirement 8.2.4a of ECSS-E-ST-
10-06 shall apply.
c. To ensure the uniqueness of a specification, requirement 8.2.5a of ECSS-
E-ST-10-06 shall apply.
d. To ensure the identification of a specification, requirement 8.2.6b of
ECSS-E-ST-10-06 shall apply.
e. To ensure the singularity of a specification, requirement 8.2.7a of ECSS-E-
ST-10-06 shall apply.
f. To ensure that a specification is verifiable, requirement 5.1.3f of ECSS-E-
ST-10-06 shall apply.
g. To ensure that a specification includes the tolerance, requirement 5.1.3g
of ECSS-E-ST-10-06 shall apply.
h. For general formatting of requirements in a specification, clause 8.3.1 of
ECSS-E-ST-10-06 shall apply.
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j. The verbal form for the wording of specification requirements shall be
compliant with requirements 8.3.2a to 8.3.2d of ECSS-E-ST-10-06.
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n. The restrictions on the format of specification requirements shall be
compliant with clause 8.3.3 of ECSS-E-ST-10-06.
5.2 Materials, parts and processes
a. Materials, parts and processes for TPHTE to be qualified shall be
documented in the following lists (see Table 5-7):
1. Declared materials list
2. Declared mechanical parts list
3. Declared processes list
5.3 General qualification requirements
5.3.1 Qualification process
a. The qualification stage shall be completed before launch.
5.3.2 Supporting infrastructure – Tools and test
equipment
a. Tools to be used to support the qualification process shall be validated
for their intended use.
b. The validation shall be performed under expected environmental
conditions and operational constraints.
c. Compatibility of tools and test equipment interfaces with flight
qualification hardware shall be verified by test.
d. Calibration of laboratory equipment shall be verified prior to their use.
e. Tools and test equipment that is modified and used in a new application
shall be re-verified according to requirements 5.3.2a to 5.3.2d.
f. Test facilities, tools and instrumentation shall be designed to avoid
adverse effects on the qualification objectives.
NOTE Examples of these are: Thermocouples, strain
gauges, heater mounting, cooling devices,
support structures.
5.4 Qualification process selection
a. The scope of the qualification process shall be adapted to the
qualification heritage of the product.
b. For categorization of the heritage the product categories of Table 5-1 shall
be used.
c. The qualification process shall be structured according to Figure 5-1.
Table 5-1
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