Abstract
The gas collecting line of a gas collecting station failed and had obvious corrosion pits. The failure reasons of the pipeline in this section are studied by means of macroscopic morphology analysis, mechanical property analysis, hardness analysis and microstructure analysis. The results show that the main reason is the mechanical damage caused in the construction process for the damage of the anticorrosive coating on the outer surface of the pipe section. The main reason for the failure of “corrosion pit” inside the pipe section is that the wet gas transported contains CO2, which dissolves in water to generate H2CO3, and the pipe section is corroded in H2CO3 solution by electrochemical corrosion, which gradually develops into a more serious corrosion pit. In order to prevent the occurrence of such failure, 13Cr (martensite) material can be used to meet the corrosion resistance requirements, but also can appropriately increase the gas temperature in the tube to reduce the solubility of CO2 in water to prevent corrosion.
Highlights
Pipeline is the most economical and safe way to transport oil and gas resources, but it is extremely vulnerable to the influence of external pressure, corrosion, third-party damage and natural disasters [1,2,3]
It is inferred that the main reason for the damage of the anti-corrosion layer on the outer surface of the pipe section may be the mechanical damage during the construction process
Since the volume of FeCO3 is smaller than that of Fe(HCO3)2, the volume shrinks during the conversion process, forming a poorly protective FeCO3 film with micropores, which leads to the corrosion of the gas gathering pipeline [22,23,24,25]
Summary
Pipeline is the most economical and safe way to transport oil and gas resources, but it is extremely vulnerable to the influence of external pressure, corrosion, third-party damage and natural disasters [1,2,3]. In oil and gas storage and transportation engineering, the chemical properties and metallographic structure of the gas collecting pipeline itself determine that this iron-based alloy is a kind of corrosion-prone alloy [4,5]. 2. Natural gas contains H2S and CO2, which form an electrochemical reaction similar to a galvanic cell and chemical reaction that destroys the metal lattice, and corrodes the gas gathering pipeline [10].
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