1 General
1.1 The guidance given in this appendix is in addition
to the requirements of 4.19, where applicable to non-metallic materials.
1.2 The manufacture, testing, inspection and
documentation of non-metallic materials should in general comply with recognized
standards, and with the specific requirements of this Code, as applicable.
1.3 When selecting a non-metallic material, the
designer should ensure that it has properties appropriate to the analysis and
specification of the system requirements. A material can be selected to fulfil one
or more requirements.
1.4 A wide range of non-metallic materials may be
considered. Therefore, the section below on material selection criteria cannot cover
every eventuality and should be considered as guidance.
2 Material selection
criteria
2.1 Non-metallic materials may be selected for use in
various parts of liquefied gas carrier cargo systems based on consideration of the
following basic properties:
-
.1 insulation – the ability to limit heat
flow;
-
.2 load bearing – the ability to contribute to
the strength of the containment system;
-
.3 tightness – the ability to provide liquid
and vapour tight barriers;
-
.4 joining – the ability to be joined (for
example by bonding, welding or fastening).
2.2 Additional considerations may apply depending on
the specific system design.
3 Properties of materials
3.1 Flexibility of insulating material is the ability
of an insulating material to be bent or shaped easily without damage or
breakage.
3.2 Loose fill material is a homogeneous solid
generally in the form of fine particles, such as a powder or beads, normally used to
fill the voids in an inaccessible space to provide an effective insulation.
3.3 Nanomaterial is a material with properties derived
from its specific microscopic structure.
3.4 Cellular material is a material type containing
cells that are either open, closed or both and which are dispersed throughout its
mass.
3.5 Adhesive material is a product that joins or bonds
two adjacent surfaces together by an adhesive process.
3.6 Other materials are materials that are not
characterized in this section of the Code and should be identified and listed. The
relevant tests used to evaluate the suitability of material for use in the cargo
system should be identified and documented.
4 Material selection and testing requirements
4.1
Material specification
4.1.1 When the initial selection of a material has been
made, tests should be conducted to validate the suitability of this material for the
use intended.
4.1.2 The material used should clearly be identified
and the relevant tests should be fully documented.
4.1.3 Materials should be selected according to their
intended use. They should:
-
.1 be compatible with all the products that may
be carried;
-
.2 not be contaminated by any cargo nor react
with it;
-
.3 not have any characteristics or properties
affected by the cargo; and
-
.4 be capable to withstand thermal shocks
within the operating temperature range.
4.2
Material testing
The tests required for a particular material depend on the design
analysis, specification and intended duty. The list of tests below is for
illustration. Any additional tests required, for example in respect of sliding,
damping and galvanic insulation, should be identified clearly and documented.
Materials selected according to 4.1 of this appendix should be tested further
according to the following table:
Function
|
Insulation
|
Load bearing structural
|
Tightness
|
Joining
|
Mechanical tests
|
|
X
|
|
X
|
Tightness tests
|
|
|
X
|
|
Thermal tests
|
X
|
|
|
|
Thermal shock testing should submit the material and/or assembly to the
most extreme thermal gradient it will experience when in service.
4.2.1 Inherent properties of materials
4.2.1.1 Tests should be carried out to ensure that the
inherent properties of the material selected will not have any negative impact in
respect of the use intended.
4.2.1.2 For all selected materials, the following
properties should be evaluated:
-
.1 density; example standard ISO 845; and
-
.2 linear coefficient of thermal expansion
(LCTE); example standard ISO 11359 across the widest specified operating
temperature range. However, for loose fill material the volumetric
coefficient of thermal expansion (VCTE) should be evaluated, as this is more
relevant.
4.2.1.3 Irrespective of its inherent properties and
intended duty, all materials selected should be tested for the design service
temperature range down to 5°C below the minimum design temperature, but not lower
than -196°C.
4.2.1.4 Each property evaluation test should be
performed in accordance with recognized standards. Where there are no such
standards, the test procedure proposed should be fully detailed and submitted to the
Administration for acceptance. Sampling should be sufficient to ensure a true
representation of the properties of the material selected.
4.2.2 Mechanical tests
4.2.2.1 The mechanical tests should be performed in
accordance with the following table.
Mechanical tests
|
Load bearing
structural
|
Tensile
|
ISO 527
|
ISO 1421
|
ISO 3346
|
ISO 1926
|
Shearing
|
ISO 4587
|
ISO 3347
|
ISO 1922
|
ISO 6237
|
Compressive
|
ISO 604
|
ISO 844
|
ISO 3132
|
Bending
|
ISO 3133
|
ISO 14679
|
Creep
|
ISO 7850
|
4.2.2.2 If the chosen function for a material relies on
particular properties such as tensile, compressive and shear strength, yield stress,
modulus or elongation, these properties should be tested to a recognized standard.
If the properties required are assessed by numerical simulation according to a high
order behaviour law, the testing should be performed to the satisfaction of the
Administration.
4.2.2.3 Creep may be caused by sustained loads, for
example cargo pressure or structural loads. Creep testing should be conducted based
on the loads expected to be encountered during the design life of the containment
system.
4.2.3 Tightness tests
4.2.3.1 The tightness requirement for the material
should relate to its operational functionality.
4.2.3.2 Tightness tests should be conducted to give a
measurement of the material's permeability in the configuration corresponding to the
application envisaged (e.g. thickness and stress conditions) using the fluid to be
retained (e.g. cargo, water vapour or trace gas).
4.2.3.3 The tightness tests should be based on the
tests indicated as examples in the following table.
Tightness tests
|
Tightness
|
Porosity/Permeability
|
ISO 15106
|
ISO 2528
|
ISO 2782
|
4.2.4 Thermal conductivity tests
4.2.4.1 Thermal conductivity tests should be
representative of the lifecycle of the insulation material so its properties over
the design life of the cargo system can be assessed. If these properties are likely
to deteriorate over time, the material should be aged as best possible in an
environment corresponding to its lifecycle, for example operating temperature,
light, vapour and installation (e.g. packaging, bags, boxes, etc.).
4.2.4.2 Requirements for the absolute value and
acceptable range of thermal conductivity and heat capacity should be chosen taking
into account the effect on the operational efficiency of the cargo containment
system. Particular attention should also be paid to the sizing of the associated
cargo handling system and components such as safety relief valves plus vapour return
and handling equipment.
4.2.4.3 Thermal tests should be based on the tests
indicated as examples in the following table or their equivalents:
Thermal tests
|
Insulating
|
Thermal conductivity
|
ISO 8301
|
ISO 8302
|
Heat
capacity
|
x
|
4.2.5 Physical tests
4.2.5.1 In addition to the requirements of 4.19.2.3 and
4.19.3.2, the following table provides guidance and information on some of the
additional physical tests that may be considered.
Physical tests
|
Flexible insulating
|
Loose fill
|
Nano-material
|
Cellular
|
Adhesive
|
Particle
size
|
|
x
|
|
|
|
Closed cells
content
|
|
|
|
ISO
4590
|
|
Absorption/Desorption
|
ISO
12571
|
x
|
x
|
ISO 2896
|
|
Viscosity
|
|
|
|
|
ISO 2555
ISO
2431
|
Open
time
|
|
|
|
|
ISO
10364
|
Thixotropic
properties
|
|
|
|
|
x
|
Hardness
|
|
|
|
|
ISO 868
|
4.2.5.2 Requirements for loose fill material
segregation should be chosen considering its potential adverse effect on the
material properties (density, thermal conductivity) when subjected to environmental
variations such as thermal cycling and vibration.
4.2.5.3 Requirements for a material with closed cell
structures should be based on its eventual impact on gas flow and buffering capacity
during transient thermal phases.
4.2.5.4 Similarly, adsorption and absorption
requirements should take into account the potential adverse effect an uncontrolled
buffering of liquid or gas may have on the system.
5 Quality assurance and quality
control (QA/QC)
5.1
General
5.1.1 Once a material has been selected, after testing
as outlined in section 4 of this appendix, a detailed quality assurance/quality
control (QA/QC) programme should be applied to ensure the continued conformity of
the material during installation and service. This programme should consider the
material starting from the manufacturer's quality manual (QM) and then follow it
throughout the construction of the cargo system.
5.1.2 The QA/QC programme should include the procedure
for fabrication, storage, handling and preventive actions to guard against exposure
of a material to harmful effects. These may include, for example, the effect of
sunlight on some insulation materials or the contamination of material surfaces by
contact with personal products such as hand creams. The sampling methods and the
frequency of testing in the QA/QC programme should be specified to ensure the
continued conformity of the material selected throughout its production and
installation.
5.1.3 Where powder or granulated insulation is
produced, arrangements should be made to prevent compacting of the material due to
vibrations.
5.2
QA/QC during component manufacture
The QA/QC programme in respect of component manufacture should include,
as a minimum but not limited to, the following items.
5.2.1 Component identification
5.2.1.1 For each material, the manufacturer should
implement a marking system to clearly identify the production batch. The marking
system should not interfere, in any way, with the properties of the product.
5.2.1.2 The marking system should ensure complete
traceability of the component and should include:
- .1 date of production and potential expiry date;
- .2 manufacturer's references;
- .3 reference specification;
- .4 reference order; and
- .5 when necessary, any potential environmental parameters to be maintained
during transportation and storage.
5.2.2 Production sampling and audit method
5.2.2.1 Regular sampling is required during production
to ensure the quality level and continued conformity of a selected material.
5.2.2.2 The frequency, the method and the tests to be
performed should be defined in QA/QC programme; for example, these tests will
usually cover, inter alia, raw materials, process parameters and component
checks.
5.2.2.3 Process parameters and results of the
production QC tests should be in strict accordance with those detailed in the QM for
the material selected.
5.2.2.4 The objective of the audit method as described
in the QM is to control the repeatability of the process and the efficacy of the
QA/QC programme.
5.2.2.5 During auditing, auditors should be provided
with free access to all production and QC areas. Audit results should be in
accordance with the values and tolerances as stated in the relevant QM.
6 Bonding and joining process
requirement and testing
6.1
Bonding procedure qualification
6.1.1 The bonding procedure specification and
qualification test should be defined in accordance with recognized standards.
6.1.2 The bonding procedures should be fully documented
before work commences to ensure the properties of the bond are acceptable.
6.1.3 The following parameters should be considered
when developing a bonding procedure specification:
- .1 surface preparation;
- .2 materials storage and handling prior to installation;
- .3 covering-time;
- .4 open-time;
- .5 mixing ratio, deposited quantity;
- .6 environmental parameters (temperature, humidity); and
- .7 curing pressure, temperature and time.
6.1.4 Additional requirements may be included as
necessary to ensure acceptable results.
6.1.5 The bonding procedures specification should be
validated by an appropriate procedure qualification testing programme.
6.2
Personnel qualifications
6.2.1 Personnel involved in bonding processes should be
trained and qualified to recognized standards.
6.2.2 Regular tests should be made to ensure the
continued performance of people carrying out bonding operations to ensure a
consistent quality of bonding.
7 Production bonding tests and
controls
7.1
Destructive testing
During production, representative samples should be taken and tested to
check that they correspond to the required level of strength as required for the
design.
7.2
Non-destructive testing
7.2.1 During production, tests which are not
detrimental to bond integrity should be performed using an appropriate technique
such as:
- .1 visual examination;
- .2 internal defects detection (for example acoustic, ultrasonic or shear test);
and
- .3 local tightness testing.
7.2.2 If the bonds have to provide tightness as part of
their design function, a global tightness test of the cargo containment system
should be completed after the end of the erection in accordance with the designer's
and QA/QC programme.
7.2.3 The QA/QC standards should include acceptance
standards for the tightness of the bonded components when built and during the
lifecycle of the containment system.