Please give me some advice
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Basic working conditions: Liquid phase tube, material 316L, specification 89 * 6. The medium is liquid anhydrous HF/HCL/R22/R21, the working pressure is 17-18 kg, and there is a sudden perforation. Attached is the picture. Can you please analyze what kind of corrosion it is? Trachoma?
What about the great masters in corrosion technology? Please enlighten me
There are holes in the welding area. Is it because we didn’t do a 100% seamless inspection during welding?
Perforations appear in the welding affected area, mostly due to welding quality problems. From the picture, it can be seen that the welding seam shape is indeed average. Although the internal argon arc welding is formed, the quality is average.
Make a spectrum of the elbow material (take the point on the inside). This elbow already had many corrosion spots, but the perforation was in a larger location and was the first to leak. From a local perspective, there are no corrosion points in straight pipes.
There is no pitting corrosion in the pipe, but there is a lot of corrosion in the elbow, indicating that there is a quality problem in the elbow.
Localized corrosion considers individual aspects: The corrosion location occurs at the elbow and the heat affected zone of the weld. It is not known how the pipeline is arranged and whether the corrosion point is at a low point or at the junction of the liquid level. Considering the flow at the elbow, combined with the corrosion shape, there should be media erosion that contributes. Check the media flow rate and direction, and the weld reinforcement seems to be high. Is it possible that a vortex is generated here. The corrosion is in the heat-affected zone. Combined with the corrosion morphology, the corrosion expands from local pit corrosion to find the coarse-grained area with the worst structure. Once corroded to the bottom, the sound is perforated.
Hydrofluoric acid does not use stainless steel, and hydrochloric acid uses Monel alloy.
The key is to ensure that it can stay dry for a long time? Especially under special working conditions. Strengthen management and testing