Do gas mixtures play a part in tube welding?

During our time as a business we have strived to provide customers with first-rate merchandise. Our speciality comes in the form of supplying ERW tube, ensuring they are available in a myriad of sizes and shapes. This enables them to meet a host of unique specifications, making them a highly versatile choice of tubing.

Traditionally, welding stainless steel tubing calls for a black purge of argon. During non-vital applications where cost is one of the driving elements, nitrogen can also be utilised as a black purge. Just be aware that this may lead to nitride compounds forming in the weld root. This slightly minimises the corrosion resistance. For applications like ERW tube for expansive compressed air and hydraulic fluid systems where water isn’t normally inside the pipes and the chances of interior corrosion are low, this can be an adequate trade-off.

Normally, it’s common for MIG welding to depend on mixtures of carbon dioxide and argon, oxygen and argon, and three gas mixtures based on carbon dioxide, helium and argon. The mixtures in question tend to include helium or argon for the most part, with carbon dioxide accounting for less than 5% of the entire gas mix. The reason why is because carbon dioxide can decompose inside the arc and make contributions of carbon to the weld pool, manufacturing a sensitised weld that’s weak to corrosion.

Since it doesn’t support a stable welding arc easily, pure argon isn’t used in conjunction with the MIG operations. Different trace constituents, such as oxygen and carbon dioxide, can fulfil this purpose. Oxygen and argon gas mixes can only be employed to weld in the flat placement due to the fact that oxygen makes for quite the fluid molten weld puddle. Carbon dioxide/argon in tandem with Pulsed MIG can be put to use to weld in every position. The same goes for the triple mix shielding gas mixes.

At Union Steel Tubes, all of our products are made with electric resistance welding so the welds are higher quality. Each ERW tube also undergoes extensive testing to ensure it is in the best possible condition. Second best isn’t good enough for us, so we make it a point to only use the finest materials and methods when crafting our tubes.

If you have certain requirements that must be met, contact us so that we can discuss them.