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.
There are occasions where pipes need to be repaired whilst liquids are still flowing.
Heavy-duty flow stopping and line plugging may require plugs and stoppers to have long immersion in chemicals or exposure to high temperatures, which many such items are not capable of withstanding.
Providing the user with the opportunity to isolate a section of pipeline whilst essential repair work can be carried out, the Pipestoppers® Division manufacture a range of single Steel Plugs, which are ideal for more arduous duties and also available as double versions for even tougher applications involving higher pressures.
Luke Keane for HFT® said: “Our line stopping products are regarded as one of the most effective and cost saving methods of pipe isolation. Often, stopping the flow in a heavy-duty operation can be difficult."
Tungsten Electrode Grinders are essential with TIG/GTA welding. Using a Grinder that has been designed and manufactured specifically for tungsten metal is not only a much safer option, they provide more accurate results leading to as many as ten times greater number of arc strikes and giving very directional arcs without flicker or wander.
The Tungsten Electrode is one of the most important variables involved in TIG welding. Preparing your Tungsten Electrode correctly will help to improve arc starting, arc stability and consequently weld quality.
Huntingdon Fusion Techniques HFT® now manufacture the TEG-1000 Tungsten Electrode Grinder with a diamond wheel, producing smooth, perfect surface finishes that eliminate arc jumping leading to consistent welds.
Ron Sewell, Chairman for HFT® said: “Many welders today are using belt sanders or bench grinders both of which are unsuitable. Bench sanders and grinders are used for a wide selection of materials and are therefore likely to contaminate the tungsten with unwanted material, which in turn will risk a negative influence on the welded joint.”
Weld Purging is essential when welding tubes and pipes made of reactive metals such as stainless steels, titanium and zirconium.
Usually weld zones are confined with purge dams so that the use of argon purge gas is limited and waiting times are reduced. Homemade dams fabricated from paper, sponge foam, wood etc. all contain water as a liquid or a vapour. Water vapour will outgas into the purge volume during the weld process, forming oxides with the metal being welded and create the imperfections that the dams were intended to stop.
Oxidised welds will lead to rework of some kind and in bad cases cause welds to be rejected and having to be cut out and re-welded. Displacing the oxygen with an inert gas before, during and after welding helps to create welds that are free from oxidation, however the weld purge dams should be made of materials that do not outgas water vapour or any other undesirable gases.
For pipe and tube lines, the most cost-effective solution is to restrict the volume around the joint with an inflatable Tandem Weld Purging System that is available off the shelf and designed especially for the task.
Welders are often faced with challenges where high quality stainless steel, duplex and chrome steel welds are required, but where the use of purge gas is not always possible.
One solution to this problem is the use of Argweld® Weld Backing Tape™ from Huntingdon Fusion Techniques HFT®. This high temperature resistant glass fibre tape supports weld roots and eliminates the creation of slag, while removing contact with air to dramatically reduce the amount of oxidation.
Luke Keane, Technical Sales Manager for HFT® said: “Weld Backing Tape™ is a common material used for manual and automatic welding to achieve higher welding speeds and dramatically reduce the amount of post weld cleaning.
The HFT® glass fibre Weld Backing Tape™ has no true melting point so it works satisfactorily with TIG or MIG welding (GTAW or GMAW) where temperatures can reach up to 6,000ºC. This overcomes the concerns associated with ceramic fibre versions that have a melting point of 1,800ºC,
Sealing, stopping and blocking pipes where oils, hydrocarbons and petrochemicals are present can cause major inconveniences with many normal stoppers not being able to handle such conditions.
The Pipestoppers® Division at Huntingdon Fusion Techniques HFT® manufactures a Range of Inflatable Rubber Plugs for heavy-duty applications where pipes might contain liquids and gases that usual Inflatable Stoppers are not resistant to.
HFT®’s Lightweight Inflatable Rubber Plugs can withstand temperatures from -40°C (-40°F) to 70°C (158°F) and are available in sizes from 2 to 78” (51 to 1,981 mm) with each Plug having a wide degree of flexibility in diameter.
Ron Sewell, Chairman for HFT® said: “Inflatable Rubber Plugs are highly resistant to oils, hydrocarbons and petrochemicals. They are used during new pipeline installation or for carrying out routine maintenance and repairs.”