Purging large diameter pipework ready for welding can be expensive. Without restricting the volume, there is a high cost involved in inert gas used and time spent waiting for the oxygen level to reach a level low enough for welding to begin.
Weld Purging experts Huntingdon Fusion Techniques HFT® have designed and developed QuickPurge® Systems to dramatically reduce the space that needs to be purged, for pipes as large as 88” (2,235 mm).
HFT® was recently tasked with a special project in the USA, where pipes with 90o elbows, up to 54” (1,371 mm) ø were required to be purged.
A secondary inert shielding gas application is often required when welding reactive metals such as titanium alloys and stainless steels, to protect the weld from oxidation until it has cooled to a safe temperature.
The low cost Argweld® Weld Trailing Shield® provides additional inert gas coverage during welding and is available from Huntingdon Fusion Techniques HFT® in flat and radiused versions.
Ron Sewell, Chairman for HFT® said: “Our Trailing Shields® simply attach onto any TIG/GTAW, PAW/Plasma and MIG/GMAW welding torch, ensuring that the weld stays under a protective inert gas coverage while the hot weld metal is cooling, preventing it from oxidising on contact with air.”
Pipe freezing for temporary pipe isolation has now become the safest, quickest and most cost-effective method for pipeline leak testing, maintenance work or for making pipe repairs including valve and other control system replacements.
It is still very common for maintenance workers to drain down entire systems before repairs can be made but this can lead to time lost spent draining and disposing of the product.
To dramatically reduce costs whilst maintaining the highest level of safety, Accu-Freeze™ pipe freezing systems are available from the Pipestoppers® Division of Huntingdon Fusion Techniques HFT®.
Vessels such as pipelines, gas cylinders and fuel tanks are often pressure tested for strength and leaks.
A range of standard and non-standard Inflatable Stoppers for tanks, chambers, tubes, pipes, pipework fabrications and ductwork is available from the Pipestoppers® Division of Huntingdon Fusion Techniques HFT®.
Ron Sewell, Chairman for HFT® said: “Our range of Inflatable Stoppers can be used for carrying out pressure tests as an alternative to mechanical test plugs.”
“Depending on the size plug, these Inflatable Stoppers have an inflation pressure of up to 10 Psi (680 mb) and will hold a back pressure of 400 mbar (5.8 Psi).”
Weld Purging Techniques are now used in most industries especially when welding reactive metals. Whilst the welding torch provides a protective cover to the top of the fusion zone, inert gas coverage is also required at the weld root.
By sampling the gas and testing the oxygen content around the weld, the welder knows when to start welding for safe results.
The basic-entry level Weld Purge Monitor®, called the PurgEye® Nano, designed and developed by Weld Purging Experts Huntingdon Fusion Techniques HFT®, will show oxygen levels down to 1 ppm (accurate to 10 ppm), which can be used to monitor the oxygen content when welding titanium, zirconium and all other reactive metals.
Pipe welders are now turning more and more to Inflatable Pipe Purging Systems because of their easy use to complete a weld faster and with less risk of oxidation, to save money from the speed and the avoidance of reject or cut outs.
These unique systems restrict weld purging zones, saving time waiting for pipes to be completely filled with argon, purged down to a low enough oxygen level to start welding safely, without the risk of oxidation.
It is still common however for some Inflatable Pipe Purging Systems to burst due to over-inflation, resulting in a lost weld and additional re-work.
To avoid such risks and to see that the inert gas being delivered to the pipe purging system is controlled, Huntingdon Fusion Techniques HFT® have designed and developed PurgeGate®, a unique valve which regulates the pressure and flow of gas that is passed through the system, ensuring that it will not burst regardless of the pressure and flow rate.
Using a high quality gas welding hose will ensure a leak tight method of feeding non-contaminated gas into the welding zone for weld purging.
Continuing their pursuit to advance in Weld Purging Technology, Huntingdon Fusion Techniques HFT® now manufacture tailor made Inert Gas Feed Hose assemblies with leak tight fittings and a low outgassing rate.
Luke Keane, Technical Sales Manager for HFT® said: “It is important when welding all reactive metals that the welding zone is purged of oxygen, even down to as low as 20 parts per million (ppm). Our Inert Gas Feed Hose assemblies are the best way of transporting argon, helium and other inert gasses to the welding zone where a guaranteed leak tight, non contaminated delivery is required.”
“All of our products are made to the highest quality and standard and are the best available for argon and helium gas use.”
With ever-improving standards in Quality Control, measuring the oxygen level around welds before, during and after welding reactive metals is crucial.
The hand held PurgEye® 200 is a Weld Purging Monitor® specifically developed and designed for use when welding titanium, zirconium, high specification stainless steel and nickel alloy joints, so that the user can produce metallurgically sound and oxide-free welds every time.
Manufactured by Weld Purging Experts Huntingdon Fusion Techniques HFT® the PurgEye® 200 is equipped with PurgeNet™, allowing accessories to be connected. These include an automatic welding machine interface so that the oxygen level in the vicinity of the weld can be continuously monitored and the welding machine can be switched on or off according to pre-set oxygen levels, an external audible and visual warning devices and a dew point monitor.
The use of home made sponge foam purge dams for pipe weld purging is still very familiar throughout the welding industry. However, operators are unaware as to how the use of sponge foam can adversely influence the metallurgical strength of a joint.
When sponge foam starts to warm up from the heat of the weld, the foam starts to outgas the harmful elements that exist throughout the foam (oxygen, nitrogen and water vapour). If the operator is unable to use a high quality Weld Purge Dam and wishes to use a low cost alternative, Huntingdon Fusion Techniques HFT® manufacture water-soluble Weld Purge Film®, ensuring all welders can achieve a great purge every time, at a reduced cost and without the introduction of harmful gases to the weld.
Ron Sewell, Chairman for HFT® said: “Making a dam with Argweld® Weld Purge Film® is much easier than all of the complex cutting and shaving that goes into the self fabrication of a sponge dam. Simply cut off a length of film from the roll, greater than the diameter of the pipe and stick the surplus film to the water-soluble adhesive that is applied to the pipe beforehand.”
Titanium is the metal of choice in a variety of industries due to its excellent corrosion resistance to acids, chlorides and salt. Titanium has a wide continuous service temperature range, from liquid nitrogen (-322°F) to 1,100°F and the highest strength-to-weight ratio of any metal.
Titanium is a reactive metal, so when heated it will react with surrounding oxygen, discolour and lose its corrosion resistance properties. In critical welding applications, it is therefore crucial that the oxygen level surrounding the weld is purged of oxygen to 50 ppm or lower.
The innovative PurgEye® Desk, a new Weld Purge Monitor® designed and manufactured by weld purging experts Huntingdon Fusion Techniques HFT®, is leading the way in inert gas purging technology by reading oxygen levels from 1,000 ppm, right down to levels as low as 1ppm (highly accurate to 10 ppm), ensuring titanium welders achieve perfect oxide free, zero colour welds time and time again.
Eliminating the need to drain long sections of pipe for repairs or modifications and reducing shut down time is now possible with Pipe Freezing Systems.
The Pipestoppers® Division at Huntingdon Fusion Techniques HFT® provides a cost saving solution with Qwik-Freezer™, the industry standard portable CO2 Pipe Freezing System.
Ron Sewell, Chairman for HFT® said: “Pipelines containing water can be frozen using liquid carbon dioxide for repairs or modifications to be made. Creating a freeze plug is a very cost effective and quick way to perform pipeline maintenance without draining the system, meaning very little or no system downtime. After the work is carried out, the ice plug is simply thawed and the line is restored to full operation.”
“It is also extremely beneficial for pipework where valves need to be changed, in industry sectors such as petrochemical, building and maintenance services, food and beverage, hospitals, water treatment, shipping and aerospace.”
It is essential to monitor the oxygen level when welding reactive metals. Metals that are classed as ‘reactive’ (titanium, zirconium and nickel alloys) are sensitive to oxygen when heated. When welding these metals, the oxygen must be purged from the welding zone, down to as low as 10 parts per million (ppm).
Weld Purging in this environment will avoid discolouration of the weld and heat affected zone and limit oxidation that could lead to a loss of metals’ corrosion resistant properties. It will help to guarantee the greatest weld joint strengths and the highest resistance to corrosion.
After 42 years of continuous Weld Purge Monitor design, Huntingdon Fusion Techniques HFT® has designed and developed yet another new Weld Purge Monitor® embracing new technological developments.
The new style PurgEye® 600 reads from atmospheric level of oxygen (20.94%), down to one part per million (0.0001%) in one instrument, offering big advantages to those manufacturing high specification products made of reactive metals.