In T-t-Ts joint - Ideally which of one is more desirable.

1. First Expansion & Then Welding.

2. First Welding & Then Expansion.

{Expansion (Any Light or full) & Welding ( Any seal 0r Strength)}

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Niraj

Niraj,
As an engineer I don't use word Ideally. There's no such thing in real life.
Just few thoughts:
If your joint configuration has weld inside the hole, then you probably would damage the expander when used after welding.
If you won't listen to the above, cold working in the weld metal might increase its fatigue strength.
If you weld the tubes with outside fillet- then these operations are independent.
If the strength of the joint is based on the expansion, then light welding done after expanding might loosen the tube and small weld might be not enough.
From the crevice corrosion point of view, expaning is usually recommended (but depends on materials).

Read also this topic: http://www.onetb.com/forum/ftopic306.html by Jugno- there can always be more problems with such connections, than you can predict.

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Konrad Anikiel

thanks

akonrad

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Niraj