川气东送天然气管道材料CO_(2)腐蚀机理研究

Research on CO Corrosion Mechanism of Natural Gas Pipeline Materials from Sichuan to East

为明确川气东送X70天然气管道材料的CO_(2)腐蚀机理问题,采用实验室试验的方法,研究了该条管道材料在天然气环境中的CO_(2)腐蚀行为,为了解管道的腐蚀状况并制定相应的防腐蚀方案奠定基础。研究表明:川气东送X70天然气管道材料处于输送温度在60℃以下时,随着温度的升高,腐蚀速率加快,此时产生的腐蚀行为属于均匀腐蚀;天然气流速为6 m/s以下时随着流速的增加,腐蚀速率加快,另外,流速越高,腐蚀速率的增加越快,且随着流速的增加,腐蚀行为将从均匀腐蚀转化为局部腐蚀;CO_(2)分压为3.5 MPa以下时,随着CO_(2)分压的加大,腐蚀速率加快,另外,在高CO_(2)分压状态下,X70管道将会产生严重的点蚀。

For making clear the CO_(2) corrosion mechanism of the X70 natural gas pipeline material from Sichuan to East,laboratory experiments were employed to study the CO_(2) corrosion behavior of the pipeline materials under natural gas environment,which could be the basis of understanding the corrosion state of pipeline and further making corresponding programs for corrosion prevention.Results showed that when the material of Sichuan to East China gas pipeline X70 was below 60℃of transportation temperature,the corrosion rate increased with temperature rising,and the corrosion behavior was uniform corrosion.When the velocity of gas was lower than 6 m/s,the increase of flow rate could accelerate the corrosion rate.Furthermore,the higher the flow rate,the faster the corrosion rate increased.With the increase of the flow rate,the corrosion behavior would be converted from uniform corrosion to local corrosion.When the CO_(2) partial pressure was lower than 3.5 MPa,the increase of CO_(2) partial pressure could make the corrosion rate faster.In addition,under high CO_(2) partial pressure,the Sichuan to East gas pipeline X70 pipeline would have severe pitting corrosion.