Root protection in special welding

Gas blend for all root protection process.

The demand of modern industry always requires    greater competence and production quality

The requests for improvement in the quality of the manufacture of pipes or containers have increased exponentially in recent years, particularly in the chemical-pharmaceutical, scientific and food sectors.

Prevent oxidation
One of the fundamental requirements imposed regarding welding pipes is to prevent oxidation of the weld during the first step.


The welding torch provides inert gas coverage of the top of the melting area, but unless precautions are taken there is no coverage of the welding root. The use of inert gases or mixtures of reducing gases allows to obtain a clean and shiny cord, even on the opposite side to the electric arc, ensuring cleanliness and avoiding the casting bath melting.

Metal reactivity

Every single material requires a

specific root protection gas.

Carbon steel, stainless steel, Duplex and Superduplex,

aluminium, and many other gases have different

metallurgical characteristics and reactivity to air.

The choice of the inert gas or reducing mixture, must be

made by following the compatibility criterion of the

material to weld and critical aspects of the atmosphere

generated inside the tank - tube to weld.

There are on the market, devices and analysers allowing

a correct and safe use of the reducing gas, thus avoiding

waste of gas or incorrect use, which voids the operating


Mixture on site

Potential production of the right onsite gas mixture.

Gas Mixer

Nippon Gases is able to meet the specific requests to generate onsite mixtures through the design and construction of specific gas mixers also, including remote control.

Root protection
This practice has become increasingly important in welding processes, especially in the chemical, pharmaceutical and food fields, with the aim of obtaining a welded joint free of surface oxidisation, also on the opposite part where it is welded.
We recommend the use of nitrogen or argon gas-based mixtures with small percentages of hydrogen depending on personal experience. It is also essential to pay specific attention when working on pipes or welding storage tanks.
In these cases, safety equipment cases must be adequate to constantly assess the risk of triggers. Even the flushing equipment is essential for correct use and significant savings of the quantities of gas applied. In this application, it's fundamental to manage the flow, which must be laminar and not turbulent. To obtain this effect the gas flow must be low.
Do you still have questions?
In Nippon Gases we have developed various qualities of gases to adapt to your applications. Call us or write to us and we will help you get the most out of it.