Thread Pitch Variation
So im an intern in a company that focuses on copper pipes. Interns dont have access to the CAD files or even allowed to take photos so heres some rough 3D models and diagrams made from my memory that i used in my slides ;
They weld the brass thread onto the copper pipe, they use copper filler wires. The welding is done with an oxy-fuel torch, it also sprays flux from the same hole. At first they made me list potential causes for this problem and suggest possible solutions, but just in case i also want to hear other causes from you as well. They deemed two of my suggestions as feasible, using nitrogen cooling and checking the zinc ratio of the brass to see if it is related. The thing is i was basically just guessing when i proposed those but now they actually want me to give details about how to implement them.
The issue with nitrogen according to the welders is that it would put out the flame from the torch, and they already seem to use nitrogen by pumping it inside the pipe itself, but the problem still seems to occur sometimes. Its not a common problem which is why i thought maybe the threads the supplier sent us had some low quality ones and thats why it occurs rarely, but we dont have the equipment to see the element ratios in the brass, which would require external lab tests so they wanted me to focus on nitrogen first.
To summarize i have 3 main questions ;
What do you think this pitch variation is caused by
If nitrogen as a solution makes sense to you, how would i implement it if we use oxy fuel torches ?
Do you have any other solutions to this problem ?
Posted Jul 29, 2026, 1:05 PM UTC