Press

Keeping Tube and Pipe Joints Clean when Welding

Posted by Michaela Reay

13-Sep-2017

huntingdonfusion.com


It is important when welding stainless steel and titanium tube and pipe joints to be able to have zero colour, oxide-free welds both on the inside and outside.

To achieve the conditions for zero colour, or oxide-free weld joints, it is necessary to remove the air around the joint to a level where the oxygen percentage is somewhere between 5 and 50 parts per million, subject to the metal and, to some extent, the application.

Removing the air from the vicinity of the weld inside and outside has to be carried out simultaneously and this is best carried out on the outside with an accessory called a Weld Trailing Shield® and on the inside with an Inflatable Pipe Purging System.

A short video showing a Trailing Shield® attached to a TIG/GTAW welding torch can be seen here https://youtu.be/9XlXBuY01iU and you will notice how super clean the outside of the weld is.

A short video showing the set up and purging of a pipe can be seen at https://youtu.be/Q-dSRpPvd1s.

The Trailing Shields® are light in weight and are carried easily by the welder as the torch is moved around the seam. As the sides are fused together, the hot metal is shielded for a very short time by the inert argon gas flowing through the welding torch and out of the ceramic gas cup. At this time, the Trailing Shield® that has also been connected to an argon supply takes over and shields the hot metal until its temperature falls below its oxidation level, thus leaving a perfectly clean weld.

In the meantime, inside the pipe, two inflatable dams tightly seal a cavity about 10” (250 mm) either side of the joint.

An argon gas supply pushes the air out and it exits through a Weld Purge Monitor® which indicates when the air has achieved an oxygen level below 50 ppm, or any other level as required by the WPS (welding procedure sheet). At that time, the welder begins his process.

Without such accessories, welding in performed in an oxidised environment, leading to loss of corrosion resistance and results in metallurgical imperfections in the joint.

Oxidised welds incur a penalty for the company, as they have to ensure that the oxidation and discolouration are totally removed by mechanical or chemical means.  Such additional work can have an effect on profitability and on delivery time.


Visit source site

huntingdonfusion.com

weld purgingweld trailing shieldstube and pipe purging systempipe purgingwelding stainless steel

More items from michaelareay


Handy Purge Monitor, now with PurgeNet™

To remain at the forefront of Weld Purging technology, World leading Weld Purging Experts and inventors of the Weld Purge Monitor®, Huntingdon Fusion Techniques HFT® have launched the updated hand-held PurgEye® 200 Weld Purge Monitor®, now with PurgeNet™. When welding metals such as stainless stee ...

Michaela Reay


Posted 5 days agoPress > weld purgingweld purge monitoroxygen reader +2

Low Cost one-way Valve for specific flow rate and pressure

This low cost accessory has been designed and constructed to pass a maximum of 7.5 litres/min and 0.5 bar pressure. Other versions of 1bar and above are also available. Designated “PurgeGate®”, this nifty, hi-tech item has applications in both fluid and gas control. Its small size and low weight m ...

Michaela Reay


Posted 19 days agoPress > purgegateinflatable pipe purgingpipe purging +2

Remote Monitoring of Weld Purge up to 1 km away

When welding lengths of tube and pipework fabrications, as well as sections of pipelines of 20 metres length and more, one problem operators face is not receiving a fast and true weld purge reading from the purge zone. Now, for the first time, Huntingdon Fusion Techniques HFT® makes it possible to ...

Michaela Reay


Posted 25 days agoPress > weld purgingweld purge monitoroxygen monitor +2

New Tungsten Electrode Grinder

Ensuring your Tungsten Electrode is sharpened correctly can help to improve weld quality. Tungsten Electrode Grinders are a convenient, safer and accurate way than other methods of grinding Tungsten Electrodes. Back by popular demand, Huntingdon Fusion Techniques HFT® have re-initiated the manufac ...

Michaela Reay


Posted 1 month agoPress > thoriated tungsten electrodestungsten electrodemultistrike +2

Introducing PurgeNet™ and Accessories

Monitoring the oxygen level before, during and after welding is essential. Welding in an environment of less then 100 ppm for stainless steel and less than 20 ppm for titanium ensures that welds are free from oxidation. Allowing joints to oxidise when welding then involves mechanical or chemical ox ...

Michaela Reay


Posted 1 month agoPress > weld purgingweld purge monitoroxygen analyzer +2
All posts from michaelareay