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What is High Purity Welding?

by Last updated Apr 18, 2024 | Published on Aug 25, 2016Welding

Estimated Reading Time: 5 minutes

By now you have heard us talk about our expertise in high purity welding. But, do most people really understand what High purity welding is? We will explain what high purity welding is, along with some of the acceptable standards for these high purity welds.What Is High Purity Welding? - Axenics

High purity welding is used in the semi-conductor and medical industries, to name a couple. High purity welding is done in a cleanroom setting where there is a controlled environment, preventing fewer contaminants from entering the weld area. This is important because the gases or fluids going through the tubing need to remain very clean. We have a great video that explains this as well below.

Weld quality and integrity is based mainly upon the penetration, oxidation, and bead of the weld. A weld is at its strongest when the bead fully penetrates the inner wall of the tubing. A partially penetrated weld is proven to be weaker.

In the industries that demand high purity welding, like semi and medical, the oxidation of the weld is another solid gage to the level of weld quality. Dirty welds, or welds with heavy oxidation, lead to contaminates getting into the contents of the system the tubing is servicing. To eliminate dirty welds, the welder purges them with an inert gas on the inside and outside, which helps reduce the oxidation levels to make a cleaner weld.

Understanding the Importance of High Purity Welding

It’s important to understand the many reasons why high purity welding is so important, and how you can ensure that your project is performed with the highest level of purity welds.

Why Is It So Important?

High purity welding is crucial to maintaining clean parts during the manufacturing process. Why? Because certain contaminants can be extremely damaging to metal tubing over time. When corrosive or oxidizing contaminants and other impurities get trapped inside the metal tubing, you risk the integrity of the entire system of which the tubing is a part. A dirty weld, or a weld with high oxidation can cause contaminants to spread throughout the entire system, and may cause a complete breakdown. The loss of time and money in such a case would be devastating.

Orbital vs. TIG Welding

Orbital welding is, by far, the cleanest and most efficient way to join tubes, flanges, elbows, joints and more, regardless of the application or industry. However, there are some applications where TIG welding is preferred, especially in cases where precise and/or extremely small welds are required, such as in welding projects for the aerospace industry, or when a weld joint is too tight and will not accommodate the orbital weld head.  

TIG welding is also often used for joining root passes, which are the most important part of a weld, and therefore the integrity and cleanliness of this type of is critical. When done properly, TIG welding is also a very clean process.

Demand for High Purity Welding

Although high purity welding is ideal for any industry, there are certain industries which absolutely require high purity welding, due to the applications for which the metal tubing is being fabricated. The semiconductor, medical device and aerospace industries are the most notable industries requiring high purity welds.

For the semiconductor industry, where there is a high risk of micro contamination, and the medical and biotech industries, where bacteria can be a significant problem, orbital welding is typically used to provide the cleanest welds possible. In the aerospace industry, however, TIG welding is used more often, due to the small size of the majority of welds required.

High Purity Environment

To ensure that welds are of the highest purity, metal tubes and fittings should be welded in a high-purity, contaminant-free environment. Therefore, it’s important to work with a manufacturing partner that is dedicated to providing the cleanest possible environment for fabrication. High purity orbital welds should achieve no less than 100% penetration to meet industry standards and to create the cleanest possible welds.  

Axenics’ Class 100 Cleanrooms

At Axenics, we weld all tubing in a Class 100 cleanroom, using a proprietary cleaning process. We use 18 megaohms (MΩ) of deionized water to clean out each tube. Our certified welders also wear cleanroom suits to prevent any contamination from getting into the tubing and welds. We also flow argon through the inside of the tubing, and through the torch, in order to prevent oxidation from occurring.

By using this process, we are able to consistently produce high quality and high purity welds that meet or exceed our customer specifications.

Axenics specializes in cleanroom orbital welding, the cleanest and most efficient way to join tubes, flanges, elbows, joints and more. Production challenges solved with welding. Get the free guide here.

If your industry or project calls for a superior high purity weld, send it to a shop that has cleanroom capabilities. Saving time or cutting corners to reduce cost by going to just any weld shop will only come back to your desk in the end.

A trained eye can look at the beading of the welded joint and quickly tell the difference between a good weld and a bad weld. A good weld is very consistent in both spacing and width throughout the entire weld. If you inspect a bad weld, you will find a wide variation in the bead width and even the length.

*Comparison of weld beads:  picture from autospeed.com

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