Chemical composition and microstructure of the tube sheet cladding
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As required by the red-lined area in the attached diagram, what specific methods are used to ensure that the chemical composition and microstructure meet the requirements of the material standards?
Sampling of the material at that location is carried out, along with testing and metallographic examination.
Have you done such retests?
This is the requirement for HG20580~585, right? If the client insists on following this standard, then follow it as required. Generally, this standard is not implemented; it can be used as a reference.
This is a requirement of GB/T151
Clad, used for test pieces, sampling. For explosive bonding, have the manufacturer conduct tests.
Has any sea traveler actually done this?
For the cladded composite tube sheets, the thickness of the transition layer and the thickness of the surface layer are specified in the drawings, to ensure that the chemical composition and corrosion resistance requirements of the material meet the minimum thickness specifications outlined in the standards. I’ve never seen a tube sheet made of explosive composite material
This post was last edited by zjq1962 on 2018-1-25 09:20. Yes, for cladded tube sheets, it is possible to achieve control by specifying the thicknesses of the transition layer and the surface layer as well as by using different welding materials. But is it necessary to include checks on chemical composition and microstructure in the process evaluation as well? It seems rather unreasonable to require re-inspection for composite panels.
The standard does not explicitly mention surfacing composite plates or explosive bonding composite plates. Impliedly, there are no restrictions on the standards; the responsibility is given to the designers, who are required to propose appropriate technical measures to ensure that the chemical composition, microstructure, and corrosion resistance meet the specified requirements. In particular, the stress conditions on the tube sheet are quite complex. According to the provisions regarding shear forces for explosive clad plates in the material section of GB/T 150.2, there is still a certain risk that the explosive clad plates may experience pulling forces between the heat exchange tubes and the tube sheet; this is one of the reasons. As for whether it is necessary to include inspections of chemical composition and microstructure in the process evaluation, NB/T 47014 specifies such requirements, as a process evaluation is needed for corrosion-resistant surfacing.