GB/T 35974.2-2018Plastics and plastic lining pressure vessels—Part 2: Material (English PDF)

1.1 Basic range

This part of GB/T 35974 specifies the applicable types, performance requirements, allowable stresses and materials for plastic and its lining pressure vessel materials. Tensile modulus of elasticity and test method.

1.2 Applicable materials and their design temperature

The usual design temperatures for the materials used in this section are.

a) Plastic containers.

1) Rigid polyvinyl chloride (PVC-U). -5 ° C ~ 60 ° C, chlorinated polyvinyl chloride (PVC-C). -5 ° C ~ 95 ° C;

2) Polyethylene (PE). -10 ° C ~ 60 ° C;

3) Polypropylene (PP). -10 ° C ~ 80 ° C;

4) Acrylonitrile butadiene styrene (ABS). -10 ° C ~ 60 ° C.

b) Lining container.

1) Rigid polyvinyl chloride (PVC-U). -5 ° C ~ 60 ° C, chlorinated polyvinyl chloride (PVC-C). -5 ° C ~ 95 ° C;

2) Polyethylene (PE). -10 ° C ~ 60 ° C;

3) Fluoroplastics. Polytetrafluoroethylene (PTFE). -20 °C ~ 140 °C, tetrafluoroethylene/ethylene copolymer (ETFE). -20 ° C ~ 140 ° C, polyvinylidene fluoride (PVDF). -20 ° C ~ 135 ° C.

3.1 Non-metallic materials

See Table 1 for common material types and processes for containers.

The lining container manufacturing process refers only to the manufacturing process of the lining layer.

3.2 Metal materials

The metal materials used for the lining containers shall comply with the relevant provisions of GB/T 150.2.

4.1 General requirements

4.1.1 Weather resistance

After the test, the appearance should be free of cracks, cracks, bubbles, erosion, chalking, and the elongation at break should be not less than 50%.

4.1.2 Corrosion resistance

The corrosion resistance of the material and its use conditions can be found in Appendix A.

4.1.3 Appearance

4.1.3.1 The surface of materials such as plates, pipes and welding rods shall be smooth and flat, and there shall be no cracks, bubbles, scratches, dents, obvious impurities and uneven color. And other defects.

4.1.3.2 Granular resin and powdered resin should be uniform in color and free from obvious impurities.

4.2 Technical requirements

4.2.1 Polyvinyl chloride (PVC)

4.2.1.1 Polyvinyl chloride material for plastic containers

The basic properties of PVC-U sheet, PVC-U tube, PVC-C tube and PVC-C sheet for welding process shall be in accordance with Table 2. Provisions.

4.2.1.2 Polyvinyl chloride material for lining containers

The basic properties of PVC-U sheet and PVC-C sheet for welding process shall comply with the requirements of Table 3.

4.2.2 Polyethylene (PE)

4.2.2.1 Polyethylene material for plastic containers

The basic properties of PE sheet, PE pipe, PE powder resin and PE particle resin for plastic containers shall comply with the requirements of Table 4.

The preparation of polyethylene powdered resin and granular resin samples was carried out in accordance with the method specified in GB/T 1845.2.

4.2.2.2 Polyethylene material for lining containers

The basic properties of PE sheet and PE powder resin for lining containers shall comply with the requirements of Table 5.

The preparation of the polyethylene powdered resin sample was carried out in accordance with the method specified in GB/T 1845.2.

4.2.3 Polypropylene (PP)

The basic properties of PP pipe, PP pellet resin and PP sheet for plastic container welding process shall comply with the requirements of Table 6.

The preparation of the polypropylene particle resin sample was carried out in accordance with the method specified in GB/T 2546.2.

4.2.4 Acrylonitrile-butadiene-styrene (ABS)

The basic properties of ABS sheet and ABS tube used in the welding process of plastic containers shall comply with the requirements of Table 7.

4.2.5 Fluoroplastics

PTFE sheet, ETFE sheet, PVDF sheet, ETFE powder, PTFE powder and PTFE film for lining container welding process The basic performance should meet the requirements of Table 8.

The preparation of the ETFE powdered resin sample was carried out in accordance with the method specified in ASTM D3159.

The preparation of the PTFE powdery resin sample was carried out in accordance with the method specified in HG/T 2902.

4.2.6 Welding materials

The basic properties of the welding materials used in the welding process shall comply with the requirements of Table 9.

The items in this table are tested in accordance with HG/T 5102.

4.3 Allowable stress and tensile modulus of elasticity

4.3.1 Model parameter determination

The long-term hydrostatic strength shall be tested in accordance with the provisions of GB/T 18252, and the parameters in the general model shall be calculated according to equation (1).

In the formula. t --- destruction time, the unit is hour (h); T --- temperature, the unit is open (K); sigma --- hydrostatic strength (ring stress) in megapascals (MPa);

C1, c2, c3, c4---the parameters used in the model; e --- error variable, obeying a normal distribution, the average is 0, and the variance is constant. It is assumed that the error is independent.

Refer to Appendix B for parameters and graphs in the minimum required static material calculation model for commonly used materials.

4.3.2 Minimum required strength

According to formula (1), when the damage time is 87600h and the probability is predicted to be 97.5%, the hydrostatic strength (ring stress) value at each temperature is calculated. It is the minimum required strength (MRS).

4.3.3 Allowable stress

The allowable stress shall be calculated according to formula (2) and the result is accurate to 0.1 MPa.

In the formula. [sigma]lt---allowable stress in megapascals (MPa); MRS---minimum required strength in MPa (MPa);

C --- safety factor, selected according to the provisions of GB/T 18475.

4.3.4 Allowable stress of commonly used materials

Typical values of allowable stresses of commonly used materials at different temperatures are shown in Table 10. The allowable stress values for each zone temperature can be entered according to equations (1) and (2). Line calculation.

When the design temperature is less than 10 °C, the allowable stress value of the material is selected according to the value of 10 °C. When the design temperature is below 0 °C, it needs to be integrated. Consider the low temperature brittleness of the material.