![]() ![]() Helium is often used as a mixture with argon to support high heat requirements during welding and enhance the penetration depth for stainless steel pipes. However, it is expensive when compared with argon. Helium: Helium is a good choice for purging when welding pipes with greater thickness and at high temperatures. The nitrogen-argon mix can also be used as a purge gas to enhance the weld’s corrosion resistance. Nitrogen is also a more economical choice compared to argon. ![]() When used with TIG welding for austenitic stainless steel, nitrogen can stabilize the delta-ferrite ratio in the weld pool to improve the tensile strength and pitting resistance in the joint. Although undesirable for use with most stainless steels, nitrogen has been used in place of argon to purge some stainless steel types. Nitrogen: Nitrogen is a reactive gas that when combined with heat can enhance the properties of the joint and prevent weld oxidation. Due to its non-reactive nature, it is suitable for high-temperature welding applications. Most standard argon used for industrial welding is 99.99% pure, but 100% pure argon can be used for high-purity applications. Its inert nature prevents oxidation and helps preserve the corrosion-resistant property of the metal while providing a clean and smooth finish. It provides the necessary blanket when welding stainless steel pipes to prevent contamination. Below, we explore each of these gases in more detail.Īrgon: Argon is the most commonly preferred purging gas by welders when using a TIG or manual welding method. Types of Purge Gases Suitable for Stainless SteelĪ common question welders face is: “What gas is best to purge stainless steel pipe during welding?” Popular options include argon, helium, and nitrogen. For stainless steel pipes used across food processing, pharmaceutical, oil and gas, nuclear, and many other industries, purging allows for welds that meet both strength and sanitary requirements. ![]() The use of inert gas prevents the chemical interaction with the molten puddle to help derive the desired weld attributes. This is observable as the granulation on the backside of the weld and can be the source of cracks, contamination, and corrosion.Ĭonsequently, purging is an important preventive measure against oxidation and contamination on the backside of the weld. However, when welding stainless steel pipes, chromium content can oxidize along the back of the weld and create a “sugaring” effect. This general mechanism would also work for metals like carbon steel or aluminum. Argon is often used as the shielding gas to protect stainless steel pipes from the external environment during welding. Welders prefer a TIG welding process for stainless steel to create strong, corrosion-resistant joints. Stainless Steel and Weld Defects From Poor Welding In this article, we will discuss these purging gases and determine the best gas for purging stainless steel during welding. Given the different types of stainless steels, inert gases like nitrogen or helium may also be options. In the case of stainless steel, however, the need for purging gas may vary. Argon, the most notable purging gas, can be effectively used with steel, aluminum, or copper alloys. When TIG welding, purging prevents issues like pitting, cracking, and splatter from arising. If you are performing a welding operation, you’re familiar with the term “ purging,” which is simply the method of extracting oxygen from the welding scene to avoid the risk of oxidation. ![]()
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