Heating issue of lye tank
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Dear bosses, I work in the field of static equipment, and I’m currently facing a problem with a large liquid caustic tank. I would like to seek your advice. Medium: 47% NaOH solution; operating temperature: 30°C. Tank material: S30408. The storage tank is equipped with an internal heating coil, and the medium flowing through this coil is hot water at a temperature of 70°C. The material of the coil is also S30408. Operating pressure: 0.3 MPa. Is it okay to use this internal heating coil in this manner? I’ve checked some information, but the opinions vary.
It is recommended to perform 100% RT inspection on the welds after coiling welding, and to carry out solution treatment on these welds; local stress corrosion is relatively severe at 70°C in the weld areas.
Thank you for the advice. Some of the experienced teachers at my workplace are also worried about the welds; they say there aren’t any major issues with the base material
Alkali corrosion is generally a concern in environments above 60°C. The temperature you mentioned is not high; it’s sufficient to prevent the alkali solution from condensing. Moreover, 304 material is being used, and as long as the welding is done properly, there’s little need to worry about anything else