Weld Purging is the act of removing oxygen from the vicinity of a weld, before, during and after welding reactive metals by displacing the oxygen with an inert gas (usually argon).
When welding stainless steel, the oxygen level must be reduced to a required minimum, which is less than 100 ppm.
The most effective way to know the oxygen level is to measure it with a Weld Purge Monitor®. Leading the way in Weld Purging Monitoring Technology, Huntingdon Fusion Techniques HFT®’s PurgEye® 100 is perfect for obtaining oxide free welds in stainless steel, reading accurately from atmospheric oxygen level (20.94%), right down to 100 ppm (0.01%).
Ron Sewell, Chairman for HFT® said: “It is important not to use alternative low cost oxygen analyzers or other oxygen safety monitors as they are calibrated under ambient conditions and therefore unsuitable for measuring purge levels down to 0.01% as our Award Winning PurgEye® 100 does.”
Weld Purging small pipes of different diameters can be challenging, especially when budgets are tight. Often, welders are left to create their own homemade purging dams out of unsuitable materials such as foam, paper or cardboard.
Weld Purging Experts Huntingdon Fusion Techniques HFT® manufacture a range of low cost, lightweight Weld Purge Plugs for a variety of applications for pipe sizes 0.5 to 6” (12 to 152 mm) diameter.
Luke Keane, Technical Sales Manager for HFT® said: “Our Weld Purge Plugs make a great barrier for purging pipes. When you have to fill complicated pipework systems with inert gas, our Weld Purge Plugs are a perfect product to seal all holes and orifices for quality internal purging.”
Inflatable Tube and Pipe Purging Systems simplify the process of inert gas purging by restricting weld purge volumes, making huge savings in time and inert gas.
Huntingdon Fusion Techniques HFT® design and manufacture PurgElite®, a range of low cost Tube and Pipe Purging Systems that help to achieve a clean, oxide free, zero colour weld in just minutes, available from 1” (25 mm).
Ron Sewell, Chairman for HFT® said: “Purging a pipe prior to welding is critical to the success of welding stainless steel, titanium, zirconium and other reactive alloys. PurgElite® systems are simply inserted in the pipe and positioned with the aid of the luminous RootGlo®. When the gas flow is started, the dams inflate, sealing inside the pipe and argon then purges the interspace automatically. A Weld Purge Monitor® connection is standard on each PurgElite®, so the welder can monitor the oxygen content of the purge volume throughout the entire welding process.”
Red tipped thoriated Tungsten Electrodes are said to contain 1.70% to 2.20% thorium. Thorium improves the quality of Tungsten Electrodes but also has a radio-toxic compound posing a risk to welders, particularly during grinding.
Huntingdon Fusion Techniques HFT®’s blue-tipped MultiStrike® Tungsten Electrodes contain a mix of non-radioactive rare earth elements, eliminating the risk to health posed by radio-toxic thoriated Tungsten Electrodes, whilst maintaining a high performing Tungsten Electrode.
Luke Keane, Technical Sales Manager for HFT® said: “Welders today continue to use thoriated Tungsten Electrodes as a cheaper alternative to other safer Tungsten Electrodes, often unaware of the risks. Because MultiStrikes® have no radiotoxic and carcinogenic additives, there is no hazardous dust to be inhaled during grinding of the tips.”
There is an ever-increasing demand in industries such as the Aerospace, Medical and Motorsport for high quality welded titanium components. Often, welding has to be carried out in an environment under 50 parts per million throughout the welding cycle.
Metal glove boxes were previously a big success, however with the lack of flexibility, heavy in weight and high cost to purchase, industries have looked to a more economical alternative.
Flexible Welding Enclosures® designed by Weld Purging Experts Huntingdon Fusion Techniques HFT® provide a low cost option, providing a very fast purging time down to a few parts per million.
The use of Flexible Welding Enclosures® has also increased during development of the Wire Arc Additive Manufacturing process, providing an inert gas shield around the titanium and other reactive alloy components.
Welders often face weld purging difficulties when working under the conditions experienced on-site including exposure to extremes of heat and cold, harmful sand and dust and even hazardous fumes, where an expensive Weld Purge Monitor® may not always be ideal.
Huntingdon Fusion Techniques HFT® have designed and developed the PurgEye® Site, which is manufactured inside a protected secure, safe, waterproof and dustproof, tough carry case, perfect for on-site welding.
Georgia Gascoyne, CEO for HFT® said: “Welding on-site does not eliminate the need to measure oxygen levels when welding metals such as stainless steel, zirconium and titanium. Often, welders are left to guess at purge levels, due to some Weld Purge Monitors® not being able to handle various on site conditions.”
Pipe stopping where access is tight can pose challenges for when duties such as repair work, leak testing and weld purging are required.
Pipestoppers®, a Division of Huntingdon Fusion Techniques HFT® design and manufacture a Range of Mechanical and Inflatable Pipestoppers® and Plugs to suit a variety of applications.
Ron Sewell, Chairman at HFT® said: “The Low Profile Stopper can fit into a pipe end that may be directly on an elbow or just inside a flanged neck on a casting. Other applications include blocking pipe ends to keep gases inside or to keep debris and vermin out.”
“When used in a vertical mode, these Low Profile Stoppers have already been used to prevent machine swarf or tools from falling into pipes, into an unrecoverable and dangerous situation, in a nuclear power steam turbine.”
Weld Purging large diameter pipework made from stainless, duplex and chrome steels, titanium or zirconium can be expensive, with requirements to have the oxygen level well below 100 ppm during the welding cycle.
As it is not cost effective to completely fill pipework with expensive inert gas, Huntingdon Fusion Techniques HFT® have developed QuickPurge® Systems to dramatically reduce the space that needs to be purged.
Ron Sewell, Chairman for HFT® said: “Welders can often spend up to half a day purging pipes, which will cost a considerable amount in time and gas costs. With the help of QuickPurge®, large diameter pipes can be purged down to 100 ppm ready for welding in just a short time. The dramatic savings in time and argon pay for the system in just one weld!”
Titanium and stainless steel are both reactive alloys. When they are heated during the welding process, they will react with any air that is present, causing oxidation, which can lead to a loss of corrosion resistance properties. Shielding the metal with an inert gas is therefore crucial and one way to measure the oxygen content within the welding zone is by using a Weld Purge Monitor®.
Leading the way in Weld Purging Technology, Huntingdon Fusion Techniques HFT®’s PurgEye® Nano is ideal for welding titanium and high end stainless steel, where oxygen levels are required to be as low as 10 ppm.
Luke Keane, Technical Sales Manager for HFT® said: “By knowing the exact level of oxygen inside the pipe at all times, the welder knows when to start welding for high quality results. The PurgEye® Nano is our basic entry level 10 ppm Monitor, which means it is perfect for restricted budgets. It’s a simple plug and play monitor, ideal for welding titanium, stainless steel and other reactive metals such as zirconium.”