What is the purpose of making the hardness of the heat exchange tube material lower than that of the tube sheet?
Thread Content
GB/T151-2014 \"Heat Exchangers\" 6.6.1.3 The hardness of the heat exchange tube material shall be lower than that of the tube sheet. What is the purpose? Is this requirement also applicable without crimping?
This requirement applies only to expansion welding; it does not apply to welding
For strength expansion, it is required that the tube sheet have a slightly higher hardness than the heat exchange tubes; for example, expansion joining of a 16Mn tube sheet with 10Mn tubes is appropriate. The purpose is to ensure that the deformation of the tube is greater than that of the tube sheet; otherwise, it loses its meaning. Other connection methods, such as strength welding, do not have such requirement for this indicator.
For manufacturing purposes, such as mounting and expansion, etc
This post was last edited by zjq1962 on 2022-2-23 at 08:28. If you read the original poster’s explanation carefully, there will be no doubts – standard 6.6.1 refers to strength expansion joining, while standard 6.6.2 deals with welding. The purpose is to ensure the pulling force for strength expansion. The 2nd floor isn’t misleading: lol
Tightening can be ensured. If the tube sheet hard pipe is too low, it won’t fit tightly.