Explosion proof variable diameter joint material: aluminum bronze, beryllium bronze, aluminum bronze material, working surface hardness HRC25 ° or above, tensile strength not less than δ B 75-85kgf/mm2 is a national grade IIB product that does not ignite gas when operating in ethylene gas with a concentration of 7.8%; Beryllium bronze material, working surface hardness HRC35 ° or above, tensile strength δ B> 105-120kgf/mm2, belonging to the national IIC level product, does not detonate gas when operating in hydrogen gas with a concentration of 21%; Beryllium copper alloy explosion-proof tools also have special anti magnetic functions, which can be used normally in working environments with magnetic fields. The above two materials of explosion-proof tools can effectively prevent flammable explosions caused by friction and impact between tools and working objects, confirming national property and personal safety! Applicable places: petroleum, chemical, mining, anti-terrorism, anti magnetic field, coal mine, gas production, oil and gas pipeline, power generation, metallurgy, high-quality, aviation, storage and transportation, pharmaceutical, gas production, plastic, chemical fiber, leather, fireworks, firecrackers, etc