ASME VIII Tubes expansion percentage limit to be considered in calculation

[FPPE]

Hi,

I have read all the posts on the forum regarding the ratio to be considered in the calculation for tubes expansion depth, but it is not clear what is the % limit that for good practice can be considered.
ASME VIII-2 gives no details on this, while API 660 (referring to a carbon steel tubes) reports a maximum tube wall thickness reduction of 8%.
Considering this, for a 150 mm thick tubesheet with a tube-to-tubesheet join expanded with two grooves in which the tube is expanded to 8% from the tube side face for 24 mm and for the following 123 mm is expanded to 6% (the 3 mm shell side is not expanded), can we consider 147 mm of expansion in the calculation? I think yes.

Thanks in advance

 

[EdStainless]

Draw a detailed picture of the conditions and think this through.
The hole in the tubesheet should see zero plastic deformation.
After all it is the spring back of the tubesheet that seals against the tube.
In reality there is a small amount of deformation because metals begin yielding long before you reach some arbitrary yield strength.
Given the actual size of the tubes and the holes how much do you have to expand the tube (and thin the wall) just to make contact?
This is why tube rolling is governed by rolling torque or expander pressure and not size.
the actual size will be different for every tube/hole combination.

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P.E. Metallurgy, consulting work welcomed