Nickel heat exchanger
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There is a heat exchanger in which the fluid flowing through the tube side is 48% alkali; the heat exchange tubes are made of nickel, while the tube sheet is fabricated from Q345R with nickel surfacing. The shell side is filled with water vapor, and the material used is Q345R. By the way, what is the weldability of Q345R after nickel surfacing? Does anyone know? Also, does the nickel material require surface treatment? Stainless steel needs to be pickled and passivated, what about nickel? This is my first time coming into contact with nickel; I would appreciate some guidance from those who are more experienced. Thank you
How many layers thick is the cladding layer on the tube sheet? We usually use composite panels; surfacing is too troublesome, and without proper protection they tend to oxidize~!
The conditions of your heat exchanger are similar to those of the heating chamber in evaporators used in alkali evaporation; for the tube sheet material, we generally use explosively bonded materials, as surfacing techniques are difficult to control and require heat treatment as well. Additionally, the inner and outer surfaces of the nickel part in the evaporator need to be pickled.
After learning this, the surface should be cleaned to remove iron ion contamination.
It is best to use explosive clad plate for the tube sheet
1. If explosive cladding plates are used, it is necessary to check whether there is compressive stress on the heat exchange tubes, to ensure compliance with the requirements of 5.3.2.2 in GB/151-2014； 2. It is also acceptable to use butt-welded tube sheets; welding poses no problem ； 3. The tube sheet is made of Q345R, and additional inspection requirements are necessary, such as UT and surface PT inspections ； It is recommended to use forgings.