I'm an engineering student looking for advice on the method needed to weld two parts together for an assignment. Please forgive my ignorance. Welding is something I would like to learn but I don't currently have the knowledge to answer my questions.
The two parts are made of aluminium and are going to be used as part of an exhaust gas system. I want to weld the two rectangular faces on the left hand end of both images (they're the same size). The dimensions of the opening are 260mm by 105mm (10.23" by 4.13"). From my limited understanding, I would need to use TIG welding for this process. I'm concerned that the welding might deform the shape if the aluminium is too thin.
My questions are,
1. What is a rough thickness of aluminium I would need to prevent deformation of the parts?
2. Approximately how much time would it take for a skilled welder to weld the distance around the outside (730 mm or 28.74 in total)?
Thank you in advance for your help.

The two parts are made of aluminium and are going to be used as part of an exhaust gas system. I want to weld the two rectangular faces on the left hand end of both images (they're the same size). The dimensions of the opening are 260mm by 105mm (10.23" by 4.13"). From my limited understanding, I would need to use TIG welding for this process. I'm concerned that the welding might deform the shape if the aluminium is too thin.
My questions are,
1. What is a rough thickness of aluminium I would need to prevent deformation of the parts?
2. Approximately how much time would it take for a skilled welder to weld the distance around the outside (730 mm or 28.74 in total)?
Thank you in advance for your help.