Hi,
When running a fixed tubesheet design in Codecalc to PD5500 Code and using ASME materials, one can easily choose ASME materials and get correct properties for common materials. However when using Cupro-Nickel tubes I cannot find an equivalent PD or EN material to use so that the program uses the correct coefficient of thermal expansion. Neither can I input my own coefficient value to over-ride the Codecalc program. It is also important to use correct properties to correctly calculate the maximum allowable longitudinal stress (compressive).

I have tried to add this material to the PD5500 database but still encounter the problem of material identification ie: its a Cu-Ni

Please advise how this problem may be overcome?

Thanks and Regards
Alan

Hi,
To add to my query above, the material used to be BS2870/2875 or CW354H or material group 2.0882
None of these appear to be listed in Codecalc. Please COADE I request you to address this query asap as I am at an absolute dead end as how to solve this problem.
Thank You
Alan

Alan,

Only PVElite will allow you to do this. CodeCalc uses the PD 5500 material group to find the equivalent TEMA material group for material properties. The material group you need will be somewhere between 31 to 38. The highest group allowed in the material database editor is 11.2. Your closest possible match for expansion values would be a stainless steel but then the modulus of elasticity value used would be out. The software should list all of the material groups to allow proper user material specification. If time is not on your side then a hand calc may be required.

By way of a suggested workaround rather than a solution can you design to TEMA instead?

Hi Stan,

Thanks for your reply. I will try model in PVElite and enter my values manually, you say I can do this for a PD5500 tubesheet design? I did find a material in the database (something like X....) that I have no idea what it is but had a very similar expansion coefficient. But as my design is rather close to requiring an expansion bellows, I was nervous about the calculation for allowable longitudinal compressive stress. Do you think my concern is warranted?

Don't think I can design to TEMA. Just like ASME Part UHX is now mandatory, so is the tubesheet calc in PD5500.
Hand calc....for a fixed tubesheet design! Its an idea but the exchanger would have corroded by the time I finish-;) Perhaps us modern engineers are too confortable with our software that such a suggestion frightens me!

Appreciate your help
Regards
Alan

Alan,

If you go to the Load Case tab in the Heat Exchanger Tubesheet Input dialog in PVElite there is a section where you can enter user defined values for the thermal expansion. So you could add your specific material to the material database to be sure of the correct mechanical properties and then user define the expansion properties (and also E values).

The differential expansion can be the major load contributor so being 'nervous' is probably the healthy option!