How to reduce the yield strength and hardness of duplex stainless steel pipes. Meets the expansion joint requirements?
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This post was last edited by zgzzsn on 2017-7-4 at 10:01. Requirements for heat exchanger tube sheets and steel tubes: strength welding + expansion bonding as specified in GB/T 151-2014, 6.6.1.3. The hardness of the heat exchange tube material should be lower than that of the tube sheet. What should be done if, for the designed materials, the mechanical properties (yield strength and hardness) of the tube sheet are lower than those of the steel tube? Tube sheet SA266 Gr2: δb: 460, δs: 260; hardness HB: 200. Steel tube S32750: δb: 800, δs: 500; hardness HB: 320. How to determine the yield strength and hardness of duplex stainless steel tubes? Meets the expansion joint requirements.
GB/T151 specifies that the hardness of the heat exchange tubes should be lower than that of the tube sheet; there are no requirements regarding the hardness of the cladding, so the original poster need not worry about this hardness issue.
Adhesive expansion isn’t an issue; the main problem is strength-related expansion