1. Classification of Welders' Safety Shoes
1. Normal Type (HP): This type does not require any heat-resistant properties and is suitable for general welding tasks where there is no significant exposure to high temperatures.
2. Low Heat Resistance Type (HN-1): Designed for environments with moderate heat exposure, this type must withstand temperatures up to 150°C ± 5°C.
3. High Heat Resistance Type (HN-2): Ideal for high-temperature welding operations, these shoes are engineered to resist temperatures as high as 250°C ± 5°C.
2. Technical Requirements for Welders' Safety Shoes
1. Material Requirements
The materials used in the upper and soles must comply with the specifications outlined in the following table. The thickness of the upper should be 0.2 mm as specified. If using materials such as cowhide, horsehide, or camel leather, the requirements for beef leather from the table should be followed.
2. Outsole Physical and Mechanical Properties
The outsole must meet the physical and mechanical performance standards detailed in the above table.
3. Tolerance of Each Part of the Same Pair of Shoes
The tolerance of all components in a matching pair of shoes must conform to the specified limits.
4. Stitch Density
The needle stitch density should be between 5 to 6.5 stitches per centimeter for regular thread and 4 to 5.5 stitches per centimeter for nylon thread.
5. Appearance Quality
The shoes must have a clean, uniform appearance without defects such as tears, stains, or uneven stitching.
6. Structural Requirements
A high-waist molding process should be used during the manufacturing of the shoes to ensure proper fit and protection.
7. Heat, Insulation, and Thermal Protection Properties
a. Heat Resistance Requirements
To test heat resistance, place the shoes on an adjustable temperature heating plate set at 250°C ± 5°C. Insert steel balls (5mm diameter, 4kg each) into the shoes and fill the surrounding area with sand up to the top edge of the shoe but not exceeding it. When the temperature reaches 150°C ± 5°C (or 250°C ± 5°C), maintain it for 20 minutes. After cooling to room temperature, check that the sole does not melt, deform, or separate. For high-heat resistance shoes, they must remain intact at 250°C ± 5°C.
b. Thermal Insulation Requirements
The test method is similar to the heat resistance test. At a temperature of 150°C ± 5°C, record the inner surface temperature of the insole every 5 minutes over 40 minutes. Calculate the average temperature and compare it with the pre-test temperature. The difference must not exceed 22°C.
c. Insulation Requirements
The shoes must meet the insulation standards specified in GB 12011-2000.
8. Burning Speed of the Upper
The upper material must not burn faster than 1 cm/s.
9. Toe Protection Requirements
The toe cap must meet the An3 standard, which requires a pressure resistance of 4.4 kN, impact resistance of 23 kg, a drop height of 120 mm, and a deformation gap greater than 15 mm.
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