welding purge oxygen sensor

Purity and quality are two crucial indicators of success in orbital welding, and they are highly dependent on each other. Impurities that rise from improper preparation and control techniques are responsible for creating defects when welding metallic workpieces. Purging is one of the most effective contamination control processes. 

The need for purging comes from the potential of atmospheric gasses like oxygen or nitrogen to invade the metallic weld pool and contaminate it. While the process is vital for sensitive metals, like stainless steel, it may not make much of a difference for mild steel. In this article, we’ll explore the importance of purging in orbital welding and when the process is required. 

What Is Purging and Why Is it Important? 

Purging creates an inert environment for welding so that the weld area is free from unwanted gasses (e.g., oxygen, nitrogen, and hydrogen) or other external contaminants. Purging is an extremely important step when pipe welding so the contaminants do not affect the underside of the weld from the pipe’s interior. There are several advantages of purging.

  • As purging makes the weld area oxygen-free, it prevents oxidation and the formation of subsequent defects, thus, improving the quality of the weld. 
  • When welding metals like stainless steel, the prevention of oxidation with purging improves the corrosion resistance of the metal. 
  • Purging reduces the damage in the weld thus eliminating waste or the need for rework. This makes the welding process much more productive and cost-effective. 
  • In industries like food and beverage and biopharmaceuticals, the need for process cleanliness is extremely important to eliminate contamination. With purging, the weld joint becomes free of contamination, helping industries achieve the desired sanitary standards. 

The use of orbital welding purge equipment allows the manufacturers to leverage these advantages. This specialized purging equipment makes the purging process more efficient and safe, improving the productivity of the orbital welding process. 

When To Use Orbital Welding Purge Equipment

The use of orbital welding purge equipment becomes important when working with metals that are highly sensitive to oxidation. This includes metals like– stainless steel, titanium, Inconel, and nickel alloys. In stainless steel, the oxidation of chromium content creates a “sugaring” effect, giving rise to cracks and corrosion. When performing orbital GTAW for stainless steel pipes, gasses, such as argon, nitrogen, and helium, are the best solutions. 

On the other hand, the use of purging gas may not have a significant benefit when welding mild steel. Due to the lower melting point of the metal, oxidation may not occur at the heat used for the welding process. It is also not practical to use a costly purging process to weld low-cost mild steel. A simple cleaning and surface preparation process is enough to create a good-quality weld with such material. 

To obtain a high-quality result with purge equipment, operators should take care of the following things:

  • Weld surfaces must be cleaned to get rid of existing contaminants.
  • Set up and operation of the orbital welding purge equipment must involve:
    • Use of purge dams to seal the pipe and isolate the weld area,
    • Supply of the inert gas for purging, and
    • Use of an oxygen sensor to monitor the oxygen content.
  • Once the weld area is deemed safe, the weld can commence. 
  • The oxygen level must be maintained throughout the weld for best results.

Effective Orbital Welding With Purging Equipment

In applications that require sanitary conditions or high-quality results, welding pipes and tubes while avoiding contaminants is crucial to achieving industry standards. Orbital welding of pipes, in itself, is a highly effective process that offers precision parameter control. But prevention of impurities while performing orbital welding can only be ensured through purging. The use of auto weld heads and orbital welding purge equipment can control the operating environment and process of welding so that manufacturers can leverage quality, productivity, and cost-efficiency with their welding applications.

Arc Machines, Inc offers technologies such as orbital weld heads and orbital welding purge equipment, to ensure your weld result is contaminant-free and high-quality. For inquiries regarding products, contact sales@arcmachines.com. For service inquiries, contact service@arcmachines.com. To develop a custom solution, contact us to arrange a meeting.

Engineering Department | Arc Machines, Inc.

The first engineers at Arc Machines were also part of NASA’s Apollo program, and we continue to hold our staff to those that level of drive and quality. Not only do we produce the best welding machines on the market, but we can also build customized machinery—tailored to your operation.

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