GB/T 31480-2015Materials for high vacuum multilayer insulation of cryogenic vessel (English PDF)

3.1 High vacuum multilayer insulation

In the high vacuum multilayer insulation space of cryogenic vessel, the thermal insulation method, which is formed by the alternate combination of spacing materials and heat-resistant radiation shields.

3.2 Heat-resistant radiation shield

Metal foil, which has high reflectivity, OR film, which has metal plating.

3.3 Spacing material

The thermal-insulating material, which is used between heat-resistant radiation shields, to prevent direct contact between two adjacent heat-resistant radiation shields.

3.4 Apparent thermal conductivity

Under specified test conditions, the heat transferred per unit time, through a multilayer insulation unit thickness of insulating material.

3.5 Outgassing rate

Under the specified test conditions, the amount of gas released per unit mass of material, per unit time.

4.1 Multilayer insulation unit

4.1.1 Structure

A typical structure of the multilayer insulation unit is as shown in Figure 1. Legends.

4.2 Multilayer insulation rolls

4.2.1 Product structure

A typical structure of a multilayer insulation roll is as shown in Figure 2. Legends.

4.3 Multilayer insulation blanket

4.3.1 Product structure

The typical structure of the multilayer insulation blanket is as shown in Figure 4.

4.3.2 Models of multilayer insulation blanket and examples

The model of the multilayer insulation blanket is according to the requirements in Figure 5.

5.1 General requirements

5.1.1 The raw materials shall comply with the relevant standards; the product

5.1.2 According to the operating conditions of the cryogenic vessel, the compatibility with oxygen shall be considered, when selecting raw materials.

5.1.3 The technological properties of raw materials shall be able to meet the requirements of construction, baking temperature resistance, vacuuming of cryogenic vessels.

5.1.4 When there are special requirements, the supplier and the buyer can negotiate separately.

5.2 Spacing material

5.2.1 Types of spacing materials and their compatibility with oxygen

5.2.3 Glass fiber cloth

5.2.3.1 The glass fiber cloth shall meet the requirements of JC/T 170.

5.2.3.2 The thickness shall be tested, according to the method of GB/T 451.3, which should be 0.05 mm ~ 0.25 mm.

5.2.3.3 The longitudinal tensile strength shall be tested, according to the method of GB/T 12914, which should not be less than 0.06 kN/m.

5.2.3.4 It needs to be degreased and dewaxed; the content of combustibles shall be tested, according to the method of GB/T 9914.2, which shall not exceed 0.2% (mass fraction).

5.2.4 Chemical fiber paper […]

5.3 Heat-resistant radiation shield

5.3.1 Types of heat-resistant radiation shields and their compatibility with oxygen

5.3.1.1 Typical types of heat-resistant radiation shields include aluminum foil, aluminized polyester film, etc.

5.3.1.2 The compatibility of the heat-resistant radiation shield with oxygen shall be evaluated, according to 4.2 of GB/T 31481-2015.

5.3.2 Aluminum foil

5.3.3 Aluminized polyester film

5.3.3.1 Aluminized polyester film shall comply with the requirements of BB/T 0030-2004.The surface shall have a continuous, bright luster, without oil traces; the edges shall be smooth and flat. Looking at the light source, there shall be no obvious scratches, holes, impurities, or aluminized layer falling off.

5.3.3.2 The base material of aluminized polyester film shall comply with the provisions of GB/T 16958; the thickness should be 0.005 mm ~ 0.025 mm.

6.1 Manufacturing environment requirements

6.1.1 The whole manufacturing process shall be carried out in a clean environment.

6.2 Manufacturing requirements for multilayer insulation units

6.2.1 The heat-resistant radiation shield can be provided with ventilation holes.

6.2.2 The spacing material and the heat-resistant radiation shield layer shall not be fixed by chemical adhesives, such as adhesives and tapes.

6.2.3 The surface of the multilayer insulation unit shall be clean; there shall be no oil stains, sweat stains, fingerprints, or other stains.

6.2.6 Apparent thermal conductivity

Take a representative sample of the multilayer insulation unit for testing. The apparent thermal conductivity shall not be greater than 1.35 x 10^-4 W/(m·K).

6.2.7 Outgassing rate

Take a representative sample of the multilayer insulation unit for testing. The outgassing rate shall not exceed 8 x 10^-7 Pa·m3/(s·g).

6.3 Manufacturing requirements for products

6.3.1 General requirements

6.3.2 Manufacturing requirements for multilayer insulation rolls

6.3.2.1 Aluminum foil tape should be used for the joint of spacing material or heat-resistant radiation shield. It shall not use organic substrate tape. The interlayer joints shall be staggered.

6.3.3 Manufacturing requirements for multilayer insulation blankets

6.3.3.1 Fixing measures shall be taken between the multilayer insulation units; the fixings shall be clean and evenly distributed.

6.3.3.2 Chemical adhesives, such as adhesives and tapes, shall not be used for fixing.

7.1 Appearance quality

The appearance quality shall be visually inspected as required. The surface cleanliness shall meet the requirements of 6.3.1.1.

7.2 Indentation of the heat-resistant radiation shield

The indentation of the heat-resistant radiation shield shall be tested, according to the method of GB/T 451.1, which is expressed as the distance between the edge of the heat-resistant radiation shield and the edge of the spacing material. It shall comply with the provisions of 6.2.4.

7.3 Width deviation

The width deviation shall be tested, according to the method of GB/T 451.1, which shall comply with the provisions of 6.2.5.

7.4 Width misalignment

The width misalignment shall be tested, according to the method of GB/T 451.1, expressed as the misalignment of the same side edge of the spacing material of 2 multilayer insulation units, which shall comply with the provisions of 6.3.1.2.

7.5 Apparent thermal conductivity

The apparent thermal conductivity shall be tested, according to the method specified in Appendix A, which shall meet the requirements of 6.2.6.

7.6 Outgassing rate

The outgassing rate shall be tested, according to the method specified in Appendix B, which shall meet the requirements of 6.2.7.

7.8 Compatibility test

7.8.1 The platinum wire combustion test of representative specimen and oxygen shall be tested, according to the relevant methods in GB/T 31481-2015.

8.1 Inspection classification

The inspection is divided into multilayer insulation unit inspection, product inspection, performance test. The inspection items are as shown in Table 3.

8.2 Inspection of multilayer insulation unit

The inspection of multilayer insulation unit is a piece-by-piece inspection; the items are as specified in Table 3.

8.3 Product inspection

The product inspection is a piece-by-piece inspection; the items are as specified in Table 3.

8.4 Performance test

If it is one of the following situations, the performance test shall be carried out. The test items shall be in accordance with the provisions of Table 3.

9.1 Sign

9.1.1 Sign content

The product sign shall at least include the following. […]

9.1.2 Sign position

The product sign shall be indicated on the outer packaging.

9.2 Product exit-factory information

9.2.1 The product exit-factory information shall at least include the certificate of conformity and quality certification documents.

9.2.2 The product certificate shall at least include the following contents.

9.2.3 The quality certificate shall at least include the following contents. […]