welding purge oxygen sensor

When working on large projects like pipeline welding, you want everything to go smoothly so the weld quality is flawless. But when the hindrance is the interference of atmospheric gasses, keeping them off of the weld pool can be challenging. In addition, the presence of ambient oxygen can invite issues like corrosion when welding carbon steel pipelines. More severe consequences can ensue when the exposure occurs on high-specification, large-diameter pipelines.

On the outside or inside of the pipeline, the shielding and purging technique prevents the weld pool from being exposed to the atmosphere when performing TIG or MIG welding. In addition, the oxygen analyzer and detector can help detect the exact oxygen level to identify if it is safe to commence the weld or proceed with preventative measures.

Critical Orbital GTAW Needs an Ideal Welding Environment

When working with larger diameter pipelines, like those used in offshore projects, the welding procedures are often highly specific regarding material use, choice of shielding gas, and weld parameters. This is because such pipelines must be structurally resilient to withstand the higher flow rate.

Without an ideal welding environment, many potential defects, including cracks, corrosion, and sugaring, can lead to pipeline failure. ID purging and oxygen level monitoring is one way to ensure an ideal environment for orbital GTAW.

Purging is done before the actual commencement of the welding process. ID purging aims to displace the oxygen with inert gas and protect the inside of the pipe from atmospheric contamination during GTAW welding. The process can be explained in the following few steps –

Step 1: Prepare the pipe for welding with pipe end preparation and surface cleaning. Make sure there is no rust, paint, oxides, or grease.

Step 2: Shield the inside of the pipe by sealing both ends of the pipe with purge dams.

Step 3: Join the ends of the pipe together and ensure they are properly aligned.

Step 4: Fill the pipe with the shielding gas to displace the unwanted gasses. For orbital GTAW, inert gas like argon or helium should be used.

Step 5: Place an oxygen sensor inside the pipe and determine if the oxygen concentration level is safe to carry forward the welding process.

Step 6: Perform the weld once 100% of the oxygen level is purged.

It is important for the pressure condition to be constant for purging, oxygen detection, and welding so no oxygen level occurs between these steps.

Advantages of Using an Oxygen Detector

The oxygen detector verifies the efficiency of the purging process. When inserted inside the pipe being purged, the oxygen detector measures if the oxygen level at the backside of the weld is within an acceptable limit (i.e., less than 2 ppm or ideally 0%). As a result, the following benefits can be achieved while welding –

  • Welds are high-purity and high-quality due to lack of contamination
  • Minimal weld defect from reduced oxidation
  • Easy and accurate oxygen level detection reduces purging time
  • Minimal and controlled consumption of purge gas

Welders may choose from oxygen analyzers of different capabilities and features depending on the purity level requirement. AMI’s M200 Oxygen Analyzer is a perfect solution when a precision sensor is desired for the orbital GTAW of pipelines. The device also offers the following features –

  1. Detection of oxygen levels within the range of 1 to 1000 ppm
  2. Remote data transfer ability
  3. Resistant to water or humidity
  4. Zirconium sensor
  5. Programmable when used with M217/M217P power supply

Improve Weld Quality With Oxygen Detector

Orbital GTAW has been a go-to process for achieving weld purity through shielding, automation, and parameter control. Many critical industrial applications rely on this welding technique, and they require welds to meet comprehensive safety and quality standards. Powerful oxygen detector technology can help eliminate weld exposure to oxygen to ensure high-purity welds. Paired with an orbital GTAW machine and auto weld head, the oxygen analyzer can increase weld productivity and efficiency.

Arc Machines, Inc., a leader in orbital welding technologies, provides oxygen detectors for your orbital GTAW application so you can reliably measure the oxygen level for producing better welds. To learn more about our products, contact sales@arcmachines.com. For service inquiries, contact service@arcmachines.com. Contact us to arrange a meeting. Arc Machines welcomes the opportunity to discuss your specific needs.


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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