NismoBgt wrote:My only recomendation for you would be to purge the inside of the tubing with gas or flux. Even more so if you are welding 321 or inconel. Notice the heat discoloration on the tubing this is a sign that the tube is outgassing INSIDE and getting impuritys in the weld. When you weld thicker materials its not apperent becouse you dont have burn thru. But THIN gauge material the backside of the weld is exposed. You will also be able to tell by a lava type or porus looking weld INSIDE the tube. Heat will stress those types of welds and cause them to break over time. Probaby the reason the other manifolds failed. TO ALL OF YOU OUT THERE THE BEST ADVICE I CAN GIVE YOU IS CLEAN YOUR MATERIAL PRIOR TO WELDING. Even with a bubble gum machine. Its the number one cause of poor quality welds and failures.
yeah im thinking after some problems welding these that i should be backpurging, most people say its not needed on mild, but i was noticing that even with cleaning the pipes really good inside and out that i was running into problems with contaminates, and felt like i was loosing gas coverage, i thought it might just be the pipes, because only a few spots would do it and it would kinda pop and blow out into a hole.
i have a backpurge setup on my rig, so its not a problem to set it up for welding thin gauge stuff, i have it setup for when i weld SS 8gauge manifolds up.
i too can not stress enough cleaning the materials. its even more important with aluminum welding.