What is ‘Weld Purging’ (purging in welding)?
When metals such as stainless steel, titanium and zirconium are welded in contact with air, the metals’ metallic elements may combine with oxygen and nitrogen to form undesirable compounds. This would lead to reduction in corrosion resistance and metallurgical defects.
To prevent these events, such metals should be welded in an environment free from air and it would be necessary to reduce (purge) the oxygen content below 50 parts per million for stainless steels and 20 ppm for titanium and zirconium so that the weld surfaces and the adjacent hot metal do not react with air and thereby cause loss of corrosion resistance and create metallurgical imperfections.
When to ‘Weld Purge (purge in weld)’?
The list of industries that fall within the Weld Purging category is endless!
Lets take a look at some examples.
Food and Beverage: When stainless steel tubes and pipes in the food and beverage industry are welded, it is crucial welding is carried out internally and preferably externally as well, in an inert environment. If there were oxygen present, the weld would become affected.
Externally oxidation and discolouration could cause loss of corrosion resistance and metallurgical imperfections that could influence the integrity of the joint. Internally the oxidation could cause uneven roots thus potentially trapping product that could support build up of bacteria thus contaminating the product being passed through the pipe.
Needless to say the costs to the operator would be much higher than the use of professionally manufactured weld purging products.
Titanium Bicycle Frames, Racecar and Aeroplane components: Due to its metallurgy, titanium must be welded in an extremely low inert environment.
In order maintain joint integrity, titanium components should be welded in an inert environment as low as 20 ppm. Usually inside a Welding Enclosure, which ensures all aspects of the part are contiguous with argon.
Which Products to use for ‘Weld Purging’:
Huntingdon Fusion Techniques HFT ® has a vast range of Purging in Welding Products available for every application. Our range of Tube, Pipe and Pipeline Weld Purging Systems is available from 1” up to 88”. We also design and manufacture Flexible Welding Enclosures®, Weld Trailing Shields®, Weld Backing Tape®, Weld Purge Film®, Weld Purge Plugs™.
Measuring the ‘Weld Purge Quality’:
The Family Range of PurgEye ® Weld Purge Monitors measure from ambient, to levels as low as accurate to 10 ppm (parts per million).
Ron Sewell, Chairman for Huntingdon Fusion Techniques HFT ® and Gas Physicist said: “All of our products are designed and manufactured in the UK, with scientific research invested, we do not sacrifice on quality. We guarantee to help you achieve zero colour welds, time and time again.”
For more on the topic of Weld Purging, visit our Wikipedia page.
