Reasons why 16MnR pipes are prone to leakage
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In my workshop’s ammonia synthesis shift, the material used for the gas pipelines is 16MnR; the medium flowing within these pipelines is semi-water gas, with components including S, CO, CO2, N2, H2S, and steam. Pipes always have leakage points. Is this related to the material? Pressure: 0.7–0.8 MPa. Temperature: around 130. Steam temperature: around 210, the leak occurs at the point where gas and steam mix. Can the pipe material be changed to something else, such as 20R? Please share your suggestions
Using 20R won’t work; both 16MnR and 20R are prone to stress corrosion under the medium and operating conditions mentioned by the poster, and this is the main reason for leaks in 16MnR pipes. It is recommended to heat-treat the pipes
How to deal with it? Could you give a more detailed answer on the 2nd floor?
Please join QQ group 32624819 and provide me with the specific details; I will use a corrosion prediction model to run simulations for you to see why pitting corrosion occurs
What LZ is referring to is the area where steam is added to the outlet pipeline of the saturation tower; it is recommended to install a gas-liquid mixer there, made of 304 material. This should solve the problem
Stress corrosion caused by H2S is a significant risk; solutions include: 1) performing an annealing process to eliminate residual stresses, and 2) using 20R instead of 16MnR (since 20R has lower strength than 16MnR). It might be better to use 20R+PWHT (post-weld heat treatment).