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.



New service from OilVoice
Trip Shepherd is for companies who need to track their staff in areas of risk.
It's free to use, so we invite you to try it.

Visit source site

huntingdonfusion.com

weld purgingweld trailing shieldstube and pipe purging systempipe purgingwelding stainless steel

More items from michaelareay


Effective Heavy-Duty Pipe Stopping

HFT® Pipestoppers® Aluminium Plugs have been designed for use in applications where pipes carrying fluids need to be plugged or sealed. They are available up to 36'' (900mm) and can accommodate temperatures up to 250⁰C. These heavy-duty plugs are manufactured with a low-friction washer to ease tig ...

Michaela Reay


Posted 10 days agoPress > huntingdon fusionaluminium plugspipe stopping +2

Oxygen Monitor for Welding

Inert gas welding requires the elimination of oxygen from the weld zone during the welding of reactive metals including stainless steel. Before the welding process begins, the oxygen level must be reduced to a required minimum, which is less than 100 ppm when welding stainless steel.  The low cos ...

Michaela Reay


Posted 18 days agoPress > weld purge monitorhuntingdon fusionppm trace +1

Low Cost Weld Purge Plugs for Tube and Pipe Weld Purging

Due to tight budgets, welders sometimes have to construct their own Weld Purging Equipment, often made from materials such as paper, card, sponge or foam. Homemade dams made from such materials can often lead to loss of welds when they leak or slip from position thus flooding the welding zone with ...

Michaela Reay


Posted 24 days agoPress > weld purge plugsweld purgingback purging +1

Inflatable Pipe Weld Purging Systems Drastically Restrict Weld Purge Volumes

Inflatable Pipe Weld Purging Systems are in use worldwide, 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 to achieve a clean, oxide free, zero colour w ...

Michaela Reay


Posted 1 month agoPress > huntingdon fusionPurgElitepipe purging +2

Increase the life of your Tungsten Electrode with MultiStrike®

Thoriated tungsten electrodes are still widely used in GTAW/TIG welding despite the potential health hazards. Thoria is added primarily to stabilize the arc but it is radio-toxic and radio-toxic dust is generated during electrode grinding. To overcome the risk posed by harmful products Huntingdon ...

Michaela Reay


Posted 1 month agoPress > multistrikethoriated tungsten electrodestungsten electrides +2
All posts from michaelareay