Will Galvanized Metal Conduits Be Burned Out When Exposed To Flames

Whether galvanized metal conduits will be burned out in flames depends on the temperature and duration of the flame, as well as the material and thickness of the conduit itself. Specific analysis can be conducted from the following aspects:

1. High temperature resistance of galvanized layer

The surface galvanized layer (zinc) of galvanized metal conduit has a melting point of about 419 ℃ and a boiling point of about 907 ℃. When the flame temperature exceeds 419 ℃, the zinc layer will first melt and drip, losing its protective effect on the internal metal; If the temperature continues to rise above 907 ℃, the zinc layer will vaporize and disappear directly.

2. High temperature resistance of internal metal conduits

The substrate of galvanized conduit is usually steel (low carbon steel or galvanized steel pipe), with a melting point of about 1538 ℃, much higher than the zinc layer. Therefore:

If the flame temperature is below 1538 ℃ (such as when burning ordinary wood or plastic, the temperature is about 500-1000 ℃), the steel conduit itself will not melt in the short term, but will oxidize due to high temperature (the rusting rate will accelerate), and the strength may decrease (such as when the yield strength of steel is significantly reduced above 600 ℃).

If the flame temperature approaches or exceeds 1538 ℃ (such as when gasoline, alcohol, or other combustion aids are burned, or when subjected to strong fire for a long time), the steel conduit will gradually soften and melt, eventually being "burned out" (structurally damaged, losing its original function).

3. Judgment of "burning out" in actual scenarios

Short term small fire: If a lighter or candle burns briefly, the galvanized layer may turn black (oxidized) or partially melt, but the internal steel pipe is intact and the conduit can still be used (without loss of function).

Long term fire: such as building fires, sustained high temperature flames (temperature exceeding 1000 ℃), and complete destruction of the zinc layer, the steel pipe will deform and crack due to high temperature oxidation and strength reduction, ultimately unable to carry or conduct (considered as "burnt out").

summarize

The galvanized layer of galvanized metal conduits is easily damaged by medium to low temperature flames, but the internal steel substrate needs to be exposed to extremely high temperatures (close to the melting point of steel) and for a long time before it can be "burned out" (structural failure). In daily fires, the damage to conduits is more due to deformation or zinc layer detachment caused by high temperatures, rather than direct melting.