Calculation of inner tube wall thickness in shell-and-tube heat exchangers
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Dear helpful friend, there is a tube heat exchanger, with the design pressures for both the tube side and the shell side being 8.2 MPa, and the design temperature for both being 280 degrees. Outer tube φ89×6, inner tube φ57×8 (wall thickness obtained from external pressure calculation), material is TA10. The length is 6 meters. May I ask: how can the wall thickness of the inner tube be reduced without lowering the design pressure and temperature? Note: Standard titanium tubes do not have this wall thickness; I can customize it.
I’ve seen others calculate the inner diameter as φ57×5, but with this thickness, the internal pressure can be calculated while the external pressure cannot. And can the inner wall thickness of the equipment withstand the hydrostatic test?
1. When conducting a hydrostatic external pressure test on the inner tube, the calculated wall thickness is essential, and it represents a consideration for extreme operating conditions. 2. Reducing the wall thickness is a risky move. 3. If such items are not available, to reduce the wall thickness, is it possible from a technical perspective to lower the pressure or temperature?
Others say it is calculated using the pressure difference method; during a hydrostatic test, the inner tube maintains pressure, which reduces the external pressure on the outer tube, allowing its thickness to be reduced. And there won’t be such high external pressure during device use. I don’t understand the pressure difference method; does anyone knowledgeable know about it? I would be greatly grateful for your advice!
The so-called pressure difference method actually takes the internal pressure into account; that is, the external pressure acting on it is the pressure value obtained by subtracting the actual internal pressure from the actual external pressure, and this is also a relative value. In practical applications, such design calculation results require process control that is not entirely controllable. Generally, design institutes do not design in this way, nor do they take on such additional risks.
. . . In practical applications, it is necessary for the process control to be fully controllable. . . .
Thank you for your guidance, expert! I’ve learned a lot. :handshake