Corrosion law and mechanism of 20# low-carbon steel in near-neutral in soil were studied by experiments of buried specimens in laboratory. In three kinds of soils, the corrosion features and products were analyzed by EDS and XRD, and the relation of corrosion rates, open-circuit potential and polarization curve with times were tested. The results indicate that corrosion rates changed incessantly along. On the condition of the same times, specimens and different soil samples, the corrosive degree of 1# and 2# specimens are serious, but 3# specimen is serious lightly. The corrosion products are main non-crystalloid, Fe（OH）3 and Fe2O3.The change rules of different times and soils are different, and are accordant with that of corrosion rates. The corrosion mechanism is discussed in near-neutral soils lastly.

The ethylene cracking furnace tube is the key component of the cracking furnace; its failure will bring serious consequences such as the fire explosion etc. According to methods of Monte Carlo and risk analysis theory of API581 of American petroleum institute, it was provides qualitative and quantitatively analysis failure probability of the ethylene cracking furnace tubes for a petrochemical corporation, and obtains the failure probability of this furnace tube. Some results can be seen by the two methods, the failure probability calculated by Monte Carlo method increased with the increase of the runtime of furnace tube under creep and carburization; while the failure probability calculated by API581 only considering creep is lower than that computed by Monte Carlo method.