Could someone please take a look at why pieces are falling off the 316 stainless steel pipe when exposed to 1.6 MPa steam?
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The newly purchased 316 stainless steel pipe has reached this condition after just half a year of use, with a steam pressure of 1.0–1.6 MPa. The ones made with 304 tubes before didn’t have such problems. Could someone please help figure out what’s causing this issue?
The outer surface of the tube! Is the internal medium steam? What is an external medium?
Steam is inside the pipe, while this situation occurs outside the pipe; it is likely due to issues with the material and the medium.
There is a material test report with samples taken for testing, and no issues were found. Could it be that there’s a problem with the physical properties of the piping? I thought about it for a long time; it doesn’t seem like corrosion to me – it’s more like pieces have fallen off due to thermal expansion and contraction.
With the same medium, there were no problems using 304 material before; but after switching to 316, problems arose. It feels really weird.
This post was last edited by xlxuiin on 2018-11-13 07:55. 1. Which standard should be used for steel pipes? (As shown in the figure) Compared to 14976, the composition meets the requirements (although it is near the lower limit) ； However, compared to 13296, the NI component fails to meet the standards. 2. It indicates that 316 material is not suitable for this application; 304 material is better (the specific manufacturing process is unclear). It’s not true that 316 is always superior to 304 in every situation! 3. Compared to 304 material, the chromium contents for the two standards are 17.00–19.00 and 18.00–20.00 respectively, while the nickel content is 8.00–11.00.
The occurrence takes place outside the tube bundle, so the external fluid can be used as a reference for judgment (steam can be ruled out in this case); the external fluid is urea/potassium chloride... From the perspective of a single type of substance present and uniform corrosion patterns, such severe problems are unlikely to occur. If pinhole defects are caused by chloride ions... then both 304 and 316 materials can be affected... So it doesn’t make sense to say that 316 will be affected while 304 won’t. It’s recommended to first verify the material of the existing tube bundle... I suspect that the material might be fake. Finally... the person who spoke above is correct; it’s not right to keep raising the requirements regarding the material. What’s really important is to evaluate the economic benefits and costs involved