High-temperature protective shoes

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High-temperature protective shoes are special types of protective footwear worn by workers in high-temperature environments to shield themselves from the hazards of heat radiation, molten metal, sparks, and hot objects such as welded steel plates, steel plates that need to cool down, and the roofs of coke ovens. High-temperature protective shoes are composed of oil-impregnated leather or flame-retardant canvas for the upper, a high-temperature resistant outsole, an insole, and a heat-insulating midsole; they are typically formed through sewing, molding, or injection molding processes. High-temperature protective shoes are also known as steelmaking shoes in the metallurgical industry. Traditional steelmaking shoes are made by impregnating leather with beef tallow or lard, using white canvas for the upper, a tire with a thickness of 7–12 mm as the sole, and are sewn together using stitching techniques. The high-temperature protective shoes used on coke oven tops feature a wooden sole or canvas upper, providing good heat insulation. But it’s inconvenient to move around in. High-temperature protective shoes made of asbestos, although resistant to high temperatures and providing good heat insulation, are no longer produced today due to the harmful effects of asbestos fibers on the human body. I. Technical Requirements: High-temperature protective shoes must comply with the specifications of standard LD32-92. The main performance requirements for such shoes are as follows: 1. Heat insulation performance of the sole: The shoes to be tested are placed on an aluminum plate at 150°C (with a temperature of 4°C; the area of the plate is 400mm×200mm, and the thickness of the single-layer aluminum plate is 5–6mm). 4 kg of 5mm steel balls are placed inside the shoes, and sand is filled around the shoes up to the upper edge of the sole. The temperature of the inner surface of the sole is measured after 20 minutes. It is required that the increase in the temperature of the inner sole surface shall not exceed 22°C (i.e., the difference between the temperature of the inner sole surface before testing, t0, and the temperature of the inner sole at the end of testing, t). 2. High-temperature resistance of the outsole: A square test piece with a side length of 33 mm and a thickness of 3–7 mm was used; it was polished smooth. A copper tip under a pressure of 20 kPa was applied to the sample covered with aluminum foil at a temperature of 300°C for 60 seconds. After removing the copper tip, the test piece was taken out, and it was checked to ensure that there were no signs of softening, melting, or cracking on its surface. 3. Impact resistance of the toe cap: It shall meet the requirements specified in standard LD50-94. For insulation purposes, non-metallic linings with poor thermal conductivity, such as fiberglass linings, should be used. 4. Physical and mechanical properties of the outsole: They shall meet the relevant requirements. II. Model: High-temperature protective shoes are available in two styles: boot type (Type A) and high-waist type (Type B). The vertical height of the back part of the boot type is not less than 200 mm, while that of the high-waist type is between 100 and 130 mm.