Proper Preparation of Tubing...

As mentioned in Part 1 of this series, TIG should be employed when welding thin sections of exhaust tubing, especially when using specialized alloys such as stainless steel or Inconel. The header in Figure 1 is an Inconel Pro-Stock header fabricated by Jack Burns from 0.028" wall tubing.

The considerable control of the welding process by the operator and the inert shielding gas help assure proper weld strength for these alloys that have a propensity to form unwanted oxides during heating. This allows for proper welding of thin walled tubing commonly used in Motorsports exhaust applications. Part 2 of the series will focus on the proper preparation of the tube sections for welding. 

When welding thin sections of stainless steel tubing as used in racing exhaust headers, care must be taken to properly prepare the joints. This is a crucial step, and trying to rush through is simply not acceptable. First of all, the tubing must be clean and free of any oily residue. When tubing is mandrel bent, thick lube oils are used to help slide the mandrels through the tubes. Over the past few years, environmental rules have minimized the use of strong organic solvents, so sometimes the tubes will contain residual amounts of lube in the bend area. The residue must be removed from the tube prior to welding. Any residual lube will contaminate your welds. A squirt bottle of acetone and rag usually does the trick.