ISO 21029-1:2004

INTERNATIONAL ISO
STANDARD 21029-1
First edition
2004-12-01
Cryogenic vessels — Transportable
vacuum insulated vessels of not more
than 1 000 litres volume —
Part 1:
Design, fabrication, inspection and tests
Récipients cryogéniques — Récipients transportables, isolés sous vide,
d'un volume n'excédant pas 1 000 litres —
Partie 1: Conception, fabrication, inspection et essais

Reference number
©
ISO 2004
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©  ISO 2004
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ii © ISO 2004 – All rights reserved

Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 3
4 Symbols. 6
5 General requirements. 7
6 Mechanical loads. 7
7 Chemical effects. 8
8 Thermal conditions. 8
9 Material. 9
10 Design. 9
11 Fabrication. 52
12 Inspection and testing. 57
13 Marking and labelling . 63
Annex A (normative) Additional requirements for flammable fluids . 64
Annex B (informative) Base materials . 65
Annex C (normative) Outer jacket relief devices . 68
Annex D (normative) Elastic stress analysis. 70
Annex E (normative) Components subject to external pressure (pressure on the convex
surface) — Calculation . 79
Annex F (informative) Marking and labelling information . 84
Annex G (informative) Specific weld details. 86
Bibliography . 90

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 21029-1 was prepared by Technical Committee ISO/TC 220, Cryogenic vessels.
ISO 21029 consists of the following parts, under the general title Cryogenic vessels — Transportable vacuum
insulated vessels of not more than 1 000 litres volume:
 Part 1: Design, fabrication, inspection and tests
 Part 2: Operational requirements

iv © ISO 2004 – All rights reserved

INTERNATIONAL STANDARD ISO 21029-1:2004(E)

Cryogenic vessels — Transportable vacuum insulated vessels
of not more than 1 000 litres volume —
Part 1:
Design, fabrication, inspection and tests
1 Scope
This part of ISO 21029 specifies requirements for the design, fabrication, inspection and testing of
transportable vacuum-insulated cryogenic vessels of not more than 1 000 l volume designed to operate at a
maximum permissible pressure greater than atmospheric.
This part of ISO 21029 applies to transportable vacuum-insulated cryogenic vessels for fluids as specified in
3.1 and Table 1 and does not apply to such vessels designed for toxic fluids.
NOTE This part of ISO 21029 does not cover specific requirements for refillable liquid hydrogen tanks that are
primarily dedicated as fuel tanks in vehicles. For fuel tanks used in land vehicles, see ISO 13985.
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 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method
ISO 2244, Packaging — Complete, filled transport packages and unit loads — Horizontal impact tests
ISO 4126-2, Safety devices for protection against excessive pressure — Part 2: Bursting disc safety devices
ISO 4136, Destructive tests on welds in metallic materials — Transverse tensile test
ISO 5173, Destructive tests on welds in metallic materials — Bend tests
ISO 6520-1:1998, Welding and allied processes — Classification of geometric imperfections in metallic
materials – Part 1: Fusion welding
ISO 9606-1, Approval testing of welders — Fusion welding — Part 1: Steels
ISO 9606-2, Qualification test of welders — Fusion welding — Part 2: Aluminium and aluminium alloys
ISO 9712, Non-destructive testing — Qualification and certification of personnel
ISO 10474:1991, Steel and steel products — Inspection documents
ISO 11117, Gas cylinders — Valve protection caps and valve guards for industrial and medical gas
cylinders — Design, construction and tests
ISO 14732, Welding personnel — Approval testing of welding operators for fusion welding and of resistance
weld setters for fully mechanized and automatic welding of metallic materials
ISO 15613, Specification and qualification of welding procedures for metallic materials — Qualification based
on pre-production welding test
ISO 15614-1, Specification and qualification of welding procedures for metallic materials — Welding
procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys
ISO 15614-2, Specification and qualification of welding procedures for metallic materials — Welding
procedure test — Part 2: Arc welding of aluminium and its alloys
ISO 17636, Non-destructive testing of welds — Radiographic testing of fusion-welded joints
ISO 17637, Non-destructive testing of welds — Visual testing of fusion-welded joints
ISO 21010, Cryogenic vessels – Gas/materials compatibility
ISO 21011, Cryogenic Vessels — Valves for cryogenic service
ISO 21013-1, Cryogenic vessels — Pressure relief accessories for cryogenic service — Part 1: Reclosable
pressure relief valves
ISO 21013-2, Cryogenic vessels — Pressure relief accessories for cryogenic service — Part 2: Non-
reclosable pressure relief devices
ISO 21013-3, Cryogenic vessels — Pressure relief accessories for cryogenic service — Part 3: Sizing and
capacity determination
ISO 21014, Cryogenic vessels — Cryogenic insulation performance
ISO 21028-1, Cryogenic vessels — Toughness requirements for materials at cryogenic temperature — Part 1:
Temperatures below − 80 °C
ISO 21028-2, Cryogenic vessels —Toughness requirements for materials at cryogenic temperature — Part 2:
Temperatures between − 80 °C and − 20 °C
ISO 21029-2, Cryogenic vessels — Transportable vacuum insulated vessels of not more than 1 000 litres
volume — Part 2: Operational requirements
EN 288-1, Specification and qualification of welding procedures for metallic materials — Part 1: General rules
for fusion welding
EN 12300, Cryogenic vessels — Cleanliness for cryogenic service
EN 13068-3, Non-destructive testing — Radioscopic testing — Part 3: General principles of radioscopic
testing of metallic materials by X- and gamma rays
2 © ISO 2004 – All rights reserved

3 Terms and definitions
For the purposes of this document the following terms and definitions apply.
3.1
cryogenic fluid
refrigerated liquefied gas
1)
gas which is partially liquid because of its low temperature
NOTE In the context of this part of ISO 21029 the (refrigerated but) non-toxic gases given in Table 1 and mixtures of
them are referred to as cryogenic fluids.
Table 1 — Refrigerated but non-toxic gases
a a
UN No. Proper shipping name and description
Asphyxiant gases
1913 neon, refrigerated liquid
1951 argon, refrigerated liquid
1963 helium, refrigerated liquid
1970 krypton, refrigerated liquid
1977 nitrogen, refrigerated liquid
2187 carbon dioxide, refrigerated liquid
2591 xenon, refrigerated liquid
3136 trifluoromethane, refrigerated liquid
b
gas, refrigerated liquid, N.O.S.
Oxidizing gases
1003 air, refrigerated liquid
1073 oxygen, refrigerated liquid
2201 nitrous oxide, refrigerated liquid
b
gas, refrigerated liquid, oxidizing, N.O.S
c
Flammable gases
1038 ethylene, refrigerated liquid
1961 ethane, refrigerated liquid
1966 hydrogen, refrigerated liquid
1972 methane, refrigerated liquid or natural gas, refrigerated liquid, with high
methane content
3138 ethylene, acetylene and propylene mixture, refrigerated liquid, containing
at least 71,5 % ethylene with not more than 22,5 % acetylene and not
more than 6 % propylene
b
gas, refrigerated liquid, flammable, N.O.S
a
UN No. and proper shipping name according to UN Recommendations, 12th edition.
b N.O.S. = not otherwise specified.
c See Annex A.
1) This includes totally evaporated liquids and supercritical fluids.
3.2
transportable cryogenic vessel
thermally insulated vessel comprising a complete assembly ready for service, consisting of an inner vessel, an
outer jacket, all of the valves and equipment together with any additional framework, intended for the transport
of one or more cryogenic fluids
3.3
thermal insulation
vacuum interspace between the inner vessel and the outer jacket
NOTE The space may or may not be filled with material to reduce the heat transfer between the inner vessel and the
outer jacket.
3.4
inner vessel
vessel intended to contain the cryogenic fluid
3.5
outer jacket
gas-tight enclosure that contains the inner vessel and enables the vacuum to be established
3.6
normal operation
intended operation of the vessel at maximum permissible pressure including the handling loads defined in 3.7
3.7
handling loads
loads exerted on the transportable cryogenic vessel in all normal conditions of transport including loading,
unloading, moving by hand or by fork-lift truck
3.8
documentation
technical documents delivered by the manufacturer to the owner consisting of:
 all certificates establishing the conformity with this part of ISO 21029, e.g. material, pressure test,
cleanliness, safety devices;
 a short description of the vessel (including characteristic data, etc.);
 a list of fluids and their net mass for which the cryogenic vessel is designed;
 an operating manual (for the user) consisting of:
1) a short description of the vessel (including characteristic data, etc.);
2) a statement that the vessel is in conformity with this part of ISO 21029;
3) the instructions for normal operation.
3.9
piping system
all pipes and piping components which can come in contact with cryogenic fluids including valves, fittings,
pressure relief devices and their supports
3.10
equipment
devices that have a safety-related function with respect to pressure containment and/or control (e.g. protective
or limiting devices, regulating and monitoring devices, valves, indicators)
4 © ISO 2004 – All rights reserved

3.11
manufacturer of the transportable cryogenic vessel
company that carries out the final assembly of the transportable cryogenic vessel
3.12
gross volume of the inner vessel
volume of the inner vessel, excluding nozzles, pipes etc. determined at minimum design temperature and
atmospheric pressure
3.13
tare mass
mass of the empty transportable cryogenic vessel
3.14
net mass
maximum permissible mass of the cryogenic fluid which may be filled
NOTE 1 The maximum permissible mass is equal to the mass of the cryogenic fluid occupying 98 % of the net volume
of the inner vessel under conditions of incipient opening of the relief device with the vessel in a level attitude and the mass
of the gas at the same conditions in the remaining volume of the inner vessel.
NOTE 2 Cryogenic liquid helium can occupy 100 % of the volume of the inner vessel at any pressure.
3.15
gross mass
sum of tare mass plus net mass
3.16
pressure
pressure relative to atmospheric pressure, i.e. gauge pressure
3.17
automatic welding
welding in which the parameters are automatically controlled
NOTE Some of these parameters may be adjusted to a limited extent, either manually or automatically, during
welding to maintain the specified welding conditions.
3.18
maximum permissible pressure
p
s
maximum pressure permissible at the top of the vessel in its normal operating position
3.19
net volume of the inner vessel
volume of the shell, below the inlet to the relief devices, excluding nozzles, pipes, etc. determined at minimum
design temperature and atmospheric pressure
4 Symbols
For the purposes of this part of ISO 21029, the following symbols listed in Table 2 apply.
Table 2 — Symbols, designations and units
Symbol Designation Unit
A
cross sectional area of reinforcing element mm
C, β design factors 1
c allowance for corrosion mm
D shell diameter mm
D
external diameter e.g. of a cylindrical shell mm
a
D
internal diameter e.g. of a cylindrical shell mm
i
d
external diameter of tube or nozzle mm
a
d
diameter of opening mm
i
E Young’s modulus
N/mm
f
narrow side of rectangular or elliptical plate mm
I moment of inertia of reinforcing element mm
K material property used for design N/mm
K (e.g. K20 for material
T
material property at temperature T expressed in °C
N/mm
property at 20 °C)
l l’
buckling length mm
b, b
n
number of lobes 1
p
design pressure as defined in 10.2.3.2.1 bar
p
permissible external pressure limited by elastic buckling bar
e
p
strengthening pressure bar
k
p
permissible external pressure limited by plastic deformation bar
p
p
maximum permissible pressure bar
s
p
test pressure (see 10.2.3.2.2) bar
t
R radius of curvature e.g. inside crown radius of dished end mm
R (1 % proof stress for
e
minimum guaranteed yield stress or 0,2 % proof stress N/mm
austenitic steel)
R
minimum guaranteed tensile strength (actual or guaranteed)
N/mm
m
r radius, e.g. inside knuckle radius of dished end and cones mm
safety factor at design pressure, with respect to R
S 1
e
S
safety factor against elastic buckling at design pressure 1
k
S
safety factor against plastic deformation 1
p
s minimum thickness mm
s
actual wall thickness mm
e
u
out of roundness (see 11.5.4.2) 1
factor indicative of the utilisation of the permissible design stress in joints or
v 1
factor allowing for weakenings
x (decay-length zone) distance over which governing stress is assumed to act mm
Z auxiliary value 1
ν Poisson’s ratio 1
6 © ISO 2004 – All rights reserved

5 General requirements
5.1 The transportable cryogenic vessel shall safely withstand the mechanical and thermal loads and the
chemical effects encountered during pressure testing and normal operation. These requirements are deemed
to be satisfied if Clauses 6 to 11 are fulfilled. The vessel shall be marked in accordance with Clause 13, tested
in accordance with Clause 12 and operated in accordance with ISO 21029-2.
5.2 Transportable cryogenic vessels shall be equipped with valves and pressure relief devices configured
and installed in such a way that the vessel can be operated safely.
The inner vessel, the outer jacket and any section of pipework containing cryogenic fluid which can be trapped,
shall be protected against over pressurization.
5.3 The transportable cryogenic vessel shall be cleaned for the intended service in accordance with
EN 12300.
5.4 The manufacturer shall retain the documentation defined in 3.8 for a period required by regulations (e.g.
product liability). In addition, the manufacturer shall retain all supporting and background documentation
issued by his subcontractors (if any) which establishes that the vessel conforms to this part of ISO 21029.
6 Mechanical loads
6.1 General
The transportable cryogenic vessel shall resist the mechanical loads without suffering deformation which
could affect safety and which could lead to leakage. This requirement can be validated by:
 calculation;
 experimental method;
 calculation and experimental method.
The mechanical loads to be considered are given in 6.2 and 6.3.
6.2 Load during the pressure test
The load exerted during the pressure test is given by:
ppW 1,3 +1
( )
ts
where
p is the test pressure, in bar;
t
p is the maximum permissible pressure (= relief device set pressure), in bar;
s
+1 is the allowance for external vacuum, in bar.
6.3 Other mechanical loads
6.3.1 The following loads shall be considered to act in combination where relevant:
a) a pressure equal to the maximum permissible pressure in the inner vessel and pipework;
b) the pressure exerted by the liquid when the vessel is filled to capacity;
c) loads produced by the thermal movement of the inner vessel, outer jacket and interspace piping;
d) loads imposed in lifting and handling fixtures (at the vessel);
e) full vacuum in the outer jacket;
f) a pressure in the outer jacket equal to the set pressure of the relief device protecting the outer jacket;
g) load due to dynamic effects, when the vessel is filled to capacity, giving consideration to:
1) the inner vessel support system including attachments to the inner vessel and outer jacket;
2) the interspace and external piping;
3) the outer jacket supports and, where applicable, the supporting frame.
6.3.2 Dynamic loads during normal operation, equal to twice the mass of the inner vessel when filled to the
capacity shown on the data plate exerted by the inner vessel both horizontally and vertically, shall be
considered.
6.3.3 If the vessel has a volume of more than 100 l or a gross mass of more than 150 kg or if the height of
the centre of gravity of the fully loaded vessel is less than twice the smallest horizontal dimension at its base,
the vertically upwards acting reference load may be reduced to equal the gross mass.
7 Chemical effects
Due to their temperatures and the materials of construction used, the possibility of chemical action on the
inner surfaces in contact with the cryogenic fluids can be neglected.
Also, due to the fact that the inner vessel is inside an evacuated outer jacket, neither external corrosion of the
inner vessel, nor corrosion on the inner surfaces of the outer jacket will occur. Therefore inspection openings
are not required in the inner vessel or the outer jacket.
Corrosion allowance is also not required on surfaces in contact with the operating fluid or exposed to the
vacuum interspace between the inner vessel and the outer jacket.
8 Thermal conditions
The following thermal conditions shall be taken into account:
a) for the inner vessel and its associated equipment the full range of temperature expected;
b) for the outer jacket and equipment thereof [other than equipment covered by a)]:
 a minimum working temperature of − 20 °C;
 a maximum working temperature of 50 °C.
8 © ISO 2004 – All rights reserved

9 Material
For the materials used to manufacture the transportable cryogenic vessels, the following requirements shall
be met.
9.1 Material properties
9.1.1 Materials which are or might be in contact with cryogenic fluids shall be in accordance with the
relevant standards for compatibility. For oxygen compatibility, see ISO 21010.
9.1.2 Materials used at low temperatures shall follow the toughness requirements of the relevant standard.
For temperatures below − 80 °C, see ISO 21028-1. For non-metallic materials low temperature suitability shall
be demonstrated by providing sufficient test data.
9.1.3 The base materials, listed in Annex B, subject to meeting the extra requirements given in the main
body of this part of ISO 21029, are suitable for and may be used in the manufacture of the cryogenic vessels
conforming to this document.
9.2 Inspection certificate
9.2.1 The material shall be declared by an inspection certificate 3.1B in accordance with ISO 10474:1991.
9.2.2 The material manufactured to a recognized International Standard shall meet the testing requirements
of ISO 21028-1 and ISO 21028-2 and shall be certified by inspection certificate 3.1B in accordance with
ISO 10474:1991.
9.2.3 The delivery of material which is not manufactured to a recognized standard has to be certified by
inspection certificate 3.1A in accordance with ISO 10474:1991 confirming that the material fulfils the
requirements listed in 9.1. The material manufacturer shall follow a recognized standard for processing and
establishing the guaranteed material properties.
9.3 Materials for outer jackets and equipment
The outer jacket and the equipment not subjected to cryogenic temperature shall be manufactured from
material suitable for the intended service.
10 Design
10.1 Design options
10.1.1 General
The design shall be carried out in accordance with one of the options given in 10.1.2 or 10.1.3.
10.1.2 Design by calculation
This option requires calculation of all pressure and load-bearing components. The pressure part thicknesses
of the inner vessel and outer jacket shall be not less than the requirements given in 10.3. Additional
calculations are required to ensure the design is satisfactory for the operating conditions including an
allowance for dynamic loads.
10.1.3 Design by calculation and supplemented with experimental methods
This option requires validation of the pressure-retaining capacity by calculation except that the minimum wall
thickness requirements of Tables 3 and 4 do not apply. Structural integrity shall be validated by experiment as
described in 10.4.
The pressure-retaining capacity may be validated by experimental methods:
 if no design formulae are available for shape or material, or
 for vessels with a (p⋅⋅V) lower than 1 000 bar/l.
⋅⋅
Table 3 — Inner vessel minimum wall thickness
a
Minimum wall thickness s for reference steel
Inner vessel diameter, D
o
(mm) (mm)
D u 400
D
400 < D u 1 800 0,5 +
a
Reference steel material is material having a product R × A of 10 000. For other materials calculate the minimum thickness using
m 5
the following formula:
21,4 s
o
s =
R × A
m5
where
R is the ultimate tensile strength, in newtons per square millimetre;
m
A is the elongation at fracture, in per cent.
Table 4 — Outer jacket minimum wall thickness
a
Outer vessel diameter, D Minimum wall thickness s for reference steel
o
(mm) (mm)
D
0,5 +
D u 1 800
a
Reference steel material is material having a product R × A of 10 000. For other materials calculate the minimum thickness using
m 5
the following formula:
21,4 s
o
s =
R × A
m5
where
R is the ultimate tensile strength, in newtons per square millimetre;
m
A is the elongation at fracture, in per cent.
10 © ISO 2004 – All rights reserved

10.2 Common design requirements
10.2.1 General
The requirements of 10.2.2 to 10.2.7 are applicable to all vessels irrespective of the design validation option
used. In the event of an increase in at least one of the following parameters:
 maximum permissible pressure;
 specific mass (density) of the densest gas for which the vessel is designed;
 maximum tare weight of the inner vessel;
 nominal length and/or diameter of the inner shell;
or, in the event of any change relative to:
 the type of material or grade (e.g. stainless steel to aluminium or change of stainless steels grades);
 the fundamental shape;
 the decrease in the minimum mechanical properties of the material being used;
 the modification of the design of an assembly method concerning any part under stress, particularly as far
as the support systems between the inner vessel and the outer jacket or the inner vessel itself or the
protective frame, if any, are concerned;
the initial design programme shall be repeated to take account of these modifications.
In addition, if any changes affect the handling method or the stacking condition, the appropriate tests
(complying respectively with 10.4.4.2 and 10.4.4.3) or the relevant calculations, shall be repeated to take
account of these changes.
10.2.2 Design specification
To enable the design to be prepared, the following information, which defines a vessel type, shall be available:
 maximum permissible pressure;
 fluids to be used;
 liquid capacity;
 volume of the inner vessel;
 method of handling and securing;
 stacking arrangement.
A design document in the form of drawings with written text, if any, shall be prepared. It shall contain the
information given above plus, where applicable, the following:
 definition of which components are designed by calculation and which are validated by experiment;
 drawings with dimensions and thicknesses of load-bearing components;
 specification of all load-bearing materials including grade, class, temper, testing etc. as relevant;
 applicable material test certificates;
 location and details of welds and other joints, welding and other joining procedures, filler, joining materials
etc. as relevant;
 calculations to verify compliance with this part of ISO 21029;
 design test programme;
 non-destructive testing requirements;
 pressure test requirements;
 piping configuration including type, size and location of all valves and relief devices;
 details of lifting points and lifting procedure.
10.2.3 Design loads
10.2.3.1 General
The transportable cryogenic vessel shall be able to safely withstand the mechanical and thermal loads and the
chemical effects encountered during pressure testing and normal operation.
10.2.3.2 Inner vessel
10.2.3.2.1 The following loads shall be considered to act in combination where relevant:
a) Design pressure, p;
where
p = p + p + 1 bar (1)
s l
p is the pressure, in bars, exerted by the liquid contents when the vessel is filled to capacity and
l
subject to dynamic loading;
b) loads imposed on the inner vessel due to the mass of the inner vessel and its contents when subject to
dynamic loading;
c) load imposed by the piping due to the differential thermal movement of the inner vessel, the piping and
the outer jacket.
The following cases shall be considered:
 cooldown (inner vessel warm – piping cold);
 filling and withdrawal (inner vessel cold – piping cold);
 transhipment and storage (inner vessel cold – piping warm);
d) load imposed on the inner vessel at its support points when cooling from ambient to operating
temperature and during operation.
12 © ISO 2004 – All rights reserved

10.2.3.2.2 The design shall be evaluated for the following condition.
Pressure test: the following value shall be used for validation purposes:
p W 1,3(p + 1) bar (2)
t s
where p is the maximum permissible pressure, in bar.
s
The 1 bar is added to allow for the external vacuum. The primary membrane stress at test pressure shall not
exceed the value prescribed in the relevant regulation and in no case shall it exceed the yield stress of the
material.
For cryogenic vessels with a capacity above 450 l, the minimum test pressure shall be 3 bar. This requirement
does not apply to heating or cooling systems and related service equipment.
10.2.3.3 Outer jacket
The following loads shall be considered to act in combination where relevant:
a) an external pressure of 1 bar;
b) an internal pressure equal to the set pressure of the outer jacket pressure relief device;
c) load imposed by the inner vessel and its contents at the support points in the outer jacket when subject to
dynamic load;
d) load imposed by piping as defined in 10.2.3.2.1 d);
e) load imposed at the inner vessel support points in the outer jacket when the inner vessel cools from
ambient to operating temperature and during operation;
f) reactions at the outer jacket support points due to the mass of the transportable cryogenic vessel and its
contents when filled to capacity and subject to dynamic load (see 10.3.8).
10.2.3.4 Inner vessel supports
The inner vessel supports shall be suitable for the load defined in 10.2.3.2.1 c) plus loads due to differential
thermal movements.
10.2.3.5 Outer jacket supports
The outer jacket supports shall be suitable for the load defined in 10.2.3.3 f).
10.2.3.6 Lifting points
Lifting points shall be suitable for lifting the transportable cryogenic vessel when filled to capacity and subject
to vertical dynamic load, when lifted in accordance with the specified procedure (see 10.3.8).
10.2.3.7 Frame
Where a frame is part of the transportable cryogenic vessel it shall be suitable for the static and dynamic loads
imposed during storage, lifting and transport. This shall include loads due to stacking vessels where
applicable (see 10.3.8).
10.2.3.8 Protective guards
Guards fitted for the protection of fittings and external pipework shall be designed to withstand a load equal to
the mass of the transportable cryogenic vessel filled to capacity applied in the horizontal or vertical direction.
The load shall be equal to twice the total mass if any of the following conditions is met:
 capacity less than 100 l;
 total mass less than 150 kg;
 the height of the centre of gravity of the transportable cryogenic vessel, when filled to capacity, including
any framework elements, is more than twice the smaller horizontal dimension of its base.
10.2.3.9 Piping and valves
Piping including valves, fittings and supports shall be designed for the following loads. With the exception of a)
the loads shall be considered to act in combination where relevant:
a) pressure test: not less than the permissible working pressure p plus one bar for piping that is inside the
s
vacuum jacket;
b) pressure during operation: not less than the set pressure of the system pressure relief device;
c) thermal loads defined in 10.2.3.2.1 c);
d) dynamic loads;
e) set pressure of thermal relief devices where applicable;
f) loads generated during pressure relief discharge.
10.2.4 Corrosion allowance
Corrosion allowance is not required on surfaces in contact with the operating fluid. Corrosion allowance is not
required on other surfaces if they are adequately protected against corrosion.
10.2.5 Inspection openings
Inspection openings are not required in the inner vessel or the outer jacket, providing the requirements of
ISO 21029-2 are followed.
NOTE 1 Due to the combination of materials of construction and operating fluids, internal corrosion cannot occur.
NOTE 2 The inner vessel is inside the evacuated outer jacket and hence external corrosion of the inner vessel cannot
occur.
NOTE 3 The elimination of inspection openings also assists in maintaining the integrity of the vacuum in the interspace.
10.2.6 Pressure relief
10.2.6.1 General
Relief devices for inner vessels shall be in accordance with ISO 21013-1, -2 and -3.
Relief devices for outer jackets shall be in accordance with Annex C.
Systems shall be designed to meet the requirements given in 10.2.6.2.
14 © ISO 2004 – All rights reserved

10.2.6.2 Inner vessel
The inner vessel shall be provided with at least two pressure relief devices to protect the vessel against
excess pressure due to the following:
a) normal heat leak. Insulation performance evaluated as described in ISO 21014 shall be sufficient to
satisfy the holding time requirement of ISO 21029-2;
b) heat leak with loss of vacuum;
c) failure in the open position of a pressure build-up system.
Excess pressure means a pressure in excess of 110 % of the maximum permissible pressure for condition a)
and in excess of the test pressure for condition b) or c).
An exception is made for vessels of less than 450 l capacity where at least one pressure relief device shall be
provided.
Shut-off valves or the equivalent may be installed upstream of pressure relief devices, provided that additional
devices and interlocks are fitted to ensure that the vessel has sufficient relief capacity at all times.
The pressure relief system shall be sized so that the pressure drop during discharge does not cause the valve
to reseat instantly.
10.2.6.3 Outer jacket
A pressure relief device shall be fitted to the outer jacket. The device shall be set to open at a pressure of not
more than 1,7 bar. The discharge area of the pressure relief device shall be not less than 0,171 mm /l
capacity of the inner vessel but not less than 6 mm in diameter.
For calculating the resistance of the inner vessel and the outer vessel to the pressure, the maximum actual set
values shall be considered.
10.2.6.4 Piping
Any section of pipework containing cryogenic fluid that can be trapped shall be protected by a relief valve or
other suitable relief device.
10.2.7 Valves
Valves shall conform to ISO 21010.
10.2.8 Degree of filling
The degree of filling of large transportable vacuum-insulated vessels intended for the carriage of flammable
gases shall remain below the level at which, if the contents were raised to the temperature at which the
vapour pressure equalled the opening pressure of the safety valve, the volume of the liquid would reach 98 %
of the vessel’s net volume at that temperature. The degree of filling for helium may be 100 % of net volume.
Pre-trip inspection shall ensure that the above limits are not exceeded.
10.3 Design by calculation
10.3.1 General
When design validation is by calculation in accordance with 10.1.2 or 10.1.3 the dimensions of the inner
vessel and outer jacket shall be not less than that determined in accordance with this sub-clause.
10.3.2 Inner vessel
10.3.2.1 Wall thickness
The information given in 10.3.2.2 to 10.3.2.6, in conjunction with the calculation formulae of 10.3.7, shall be
used to determine the pressure part thicknesses.
The actual wall thickness shall be not less than as shown in Table 3 unless either:
a) the design has been validated by experiment or
b) a stress analysis has been carried out, and assessed in accordance with Annex D.
10.3.2.2 Design pressure, p
The internal design pressure p shall be as defined in 10.2.3.2.
The minimum design pressure shall be 2,31 bar.
The inner vessel shall be designed for a minimum external pressure equal to the set pressure of the outer
jacket pressure relief device.
10.3.2.3 Material property, K
The material property, K, to be used in the calculations shall be as follows:
 for austenitic stainless steel, 1 % proof strength;
 for aluminium and aluminium alloys, 0,2 % proof strength.
K shall be the minimum value at 20 °C as taken from the material standard. In the case of austenitic stainless
steels the specified minimum value may be exceeded by up to 15 % provided this higher value is attested in
the inspection certificate.
Higher values of K may be used provided that the following conditions are met:
 the material manufacturer shall guarantee compliance with this higher value, in writing, when accepting
the order;
 the increased properties shall be verified by testing each rolled plate or coil of the material to be
delivered;
 the increased properties shall be attested in the inspection certificate;
 the welding procedures shall be suitably qualified.
For austenitic stainless steel a strength value obtained in work-hardened material may be used in the design
provided this value and adequate ductility is maintained in the finished component.
16 © ISO 2004 – All rights reserved

10.3.2.4 Safety factors S, S and S
p k
The safety factors to be used are as follows:
 internal pressure (pressure on the concave surface): S = 1,33
 external pressure (pressure on the convex surface):
 cylindrical shells S = 1,4 S = 2,6
p k
 spherical region S = 2,1 S see applicable method in Annex E
p k
 knuckle region S = 1,6
p
10.3.2.5 Weld joint factors, v
For internal pressure (pressure on the concave surface) v = 0,85 or 1,0 (see Clause 12).
For external pressure (pressure on the convex surface) v = 1,0.
10.3.2.6 Corrosion allowances, c
c = 0
NOTE No corrosion allowance is required for austenitic stainless steel, aluminium and aluminium alloys.
10.3.3 Outer jacket
10.3.3.1 General
The following, in conjunction with the calculation formulae of 10.3.7, shall be used to determine the pressure
part thicknesses.
The actual wall thickness shall be not less than as shown in Table 4 unless either
a) the design has been validated by experiment or
b) a stress analysis has been carried out and assessed in accordance with Annex D.
10.3.3.2 Design pressure, p
The internal design pressure, p, shall be equal to the set pressure of the outer jacket pressure relief device.
The external design pressure shall be 1 bar.
10.3.3.3 Material property, K
The material property K to be used in the calculations shall be as follows:
 for austenitic stainless steel, aluminium and aluminium alloys, material property values shall be as
defined in 10.3.2.3;
 for carbon steel K = yield strength.
NOTE Upper yield strength may be used.
10.3.3.4 Safety factors S, S and S
p k
The safety factors to be used are as follows:
 internal pressure (pressure on the concave surface): S = 1,1
 external pressure (pressure on the convex surface):
 cylindrical shells S = 1,1 S = 2,0
p k
 spherical region S = 1,6 S = 2,0 + 0,001 4 R/s
p k
 knuckle region S = 1,2
p
10.3.3.5 Plastic deformation
Resistance to plastic deformation is determined by using Annex D with the appropriate safety factor S defined
p
in 10.3.2.4 and 10.3.3.4.
10.3.3.6 Weld joint factor, v
For internal pressure (pressure on the concave surface) v = 0,7.
For external pressure (pressure on the convex surface) v = 1,0.
10.3.3.7 Corrosion allowance, c
For austenitic stainless steel c = 0.
For aluminium and aluminium alloys c = 0.
For carbon steel c = 1,0 mm.
c may be reduced to zero if the external surface is adequately protected against corrosion.
10.3.4 Supports, lifting points and frame
The supports and frame shall be designed for the loads defined in 10.2.3, using established structural design
methods and safety factors.
When designing the inner vessel support system the temperature and corresponding mechanical properties to
be used may be those of the component in question when the inner vessel is filled to capacity with cryogenic
fluid.
10.3.5 Protective guards
External fittings shall be protected by a guard designed for the loads specified in 10.2.3.8. The requirements
are satisfied if the fittings to be protected are either:
 within a guard which is permanently attached to the transportable cryogenic vessel or
 located within the outline of the transportable cryogenic vessel, e.g. within an end which is domed
inwards.
18 © ISO 2004 – All rights reserved

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