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.

  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.