Mineral insulated cable (MI) cable, also known as magne […]
Mineral insulated cable (MI) cable, also known as magnesium oxide insulated cable, is an inorganic material cable. The mineral insulated cable is made of copper conductor, inorganic insulating material (magnesium oxide powder) and seamless copper tube or copper strip. The three kinds of inorganic materials are welded by multiple drawing or multiple rolling. to make. This unique structure makes it refractory, explosion-proof, high-temperature resistant, non-aging, does not cause fire and spreads fire, and does not release any harmful gases and fumes under the surrounding fire conditions, especially suitable for harsh environment and safety. A place or part that requires a particularly high degree of safety, especially for fire protection system lines that are to be safely powered under fire conditions. A special polyethylene or low-smoke halogen-free jacket can also be extruded on the metal sheath for special needs. Mineral insulated cables can be divided into: distribution cables, heating cables and heating elements, thermocouple cables and compensation cables, special cables, and the most commonly used wiring cables in practical applications.
At present, the national standard for the implementation of mineral insulated cables is GB/T13033.1-2007. A new type of mineral insulated special cable other than the national standard has appeared---825 alloy sheathed mineral insulated fireproof cable. The 825 alloy sheathed mineral insulated fireproof cable is designed for normal operation (transmission of electricity) in a hydrocarbon explosion flame and high corrosive environment. The cable consists of one or more conductor cores, magnesium oxide powder, and 825 alloy sheath. composition. The conductor core wire is generally a nickel-clad copper or pure nickel solid core wire. The outer sheath of the 825 alloy cable cannot be used as a grounding wire. Alloy 825 has acid and alkali corrosion resistance in both oxidizing and reducing environments. The high nickel content makes the alloy effective in stress corrosion cracking resistance. Corrosion resistance is good in various media such as sulfuric acid, phosphoric acid, nitric acid and organic acids, alkali metals such as sodium hydroxide, potassium hydroxide and hydrochloric acid. Alloy 825 is an alloy that has been found to have excellent performance in an environment where high temperature (such as petroleum and petrochemical plants) produces organic sulfur compounds, hydrogen sulfide and sulfur combustible products.
The mineral-insulated fire-resistant cable of 825 alloy sheath can survive not only in the high temperature explosion flame of 1200 °C for 30 minutes, but also has strong corrosion resistance to petroleum gas and acid mist. Tested by Exxon-Mobil Oil Company, this test placed the 825 alloy cable in an environment that closely resembles the actual hydrocarbon flash fire. The test procedure stipulates that the cable under test must be supported in a pit filled with a mixture of gasoline and diesel. When the mixture is ignited, the temperature inside the furnace rises sharply and burns violently. In the test, the cable sample under test was not only subjected to the high temperature of the flame, but also had a devastating turbulent fire. During the whole test period, the average temperature exceeded 1100 °C. Due to the characteristics of the test itself, the temperature fluctuated continuously at the level of 1100 °C. Tests have shown that the cable can continue to operate normally in the event of a fire.