The increasing popularity of Grade 9 titanium alloy has brought with it some questions about weldability.
Grade 9 titanium alloy contains 3% aluminium and 2.5% vanadium, less alloying material than the more common Grade 5 (6% aluminium and 4% vanadium). Grade 9, alternatively referred to as Ti-3-2.5, offers improved resistance to corrosion and better mechanical strength and is now routinely used in applications as diverse as aircraft hydraulic tubes and high specification bicycle frames.
Weldability of Ti-3-2.5 is good provided that the necessary precautions are taken. Due to the reactive nature of titanium and its alloys, inert gas shielding must be in place on both the OD and ID of tubes and protection assured when welding plate and sheet.
Tungsten Electrodes are used during Tungsten Inert Gas (TIG) or Plasma welding and are the most important consumable during welding. However they are often manufactured using thoria, dust from which poses a risk to health.
Recognising both the performance requirement and the health benefits, Huntingdon Fusion Techniques HFT®’s MultiStrike® Tungsten Electrodes not only deliver an increased overall performance, they also contain a mix of non-radio-toxic compounds. These MultiStrike® electrodes give at least 10 times more arc striking capacity than alternative electrodes tested under the same conditions.
MultiStrikes® can be used for welding aluminium with the AC process, as well as steels and alloys with the DC process, which allows the welder to have just one type of Tungsten Electrode to weld all materials and reduce the amount of stocks and purchasing requisitions.
For welding nickel alloy, titanium and stainless steel tubes and pipes, including stubs, elbows and tees, Huntingdon Fusion Techniques HFT® have designed and developed clinically clean, white nylon Weld Purge Plugs™, providing a great barrier for weld purging.
Luke Keane, Technical Sales Manager for HFT® said: “When other purge systems cannot be used, Weld Purge Plugs™ can be used to make a suitable barrier for purging pipes, tubes or fittings.”
“These low cost, lightweight Weld Purge Plugs™ are available for a variety of applications for pipe sizes 0.5 to 6” (12 to 152 mm) diameter eliminating the need for welders to create their own homemade purging dams out of unsuitable materials such as foam, paper or cardboard.
Weld Purge Monitors® are in use throughout the Welding Industry. Used during the welding of reactive alloys, they ensure the oxygen present is at a low enough level to avoid oxidation, which can lead to a loss of the alloys’ corrosion resistance properties.
For stainless steel, the oxygen level needs to be as low as 100 ppm. Recognising the requirement for a low cost, portable 100 ppm monitor, Weld Purging Experts Huntingdon Fusion Techniques HFT® designed and developed the PurgEye® 100 Weld Purge Monitor, which is now the World’s leading monitor for welding stainless steel.
Georgia Gascoyne, CEO Managing Director for HFT® said: “Our award winning PurgEye® 100 is really a game changer for the welding industry. Stainless steel is often the metal of choice in many different industries for its corrosion resistance properties, strength, weight and cost, so developing a monitor that can read accurately down to 100 ppm was a huge requirement.”
Reactive metals including stainless steels and titanium will react with air when they are heated during the welding process, which can cause oxidation and lead to a loss of corrosion resistance properties
Huntingdon Fusion Techniques HFT® have recently launched their new and improved Argweld Weld Trailing Shields®, providing a high quality inert gas coverage during flat sheet, plate or pipe welding.
Chairman for HFT® Ron Sewell said: “Preventing the alloy from coming into immediate contact with air is easily done with our Argweld Weld Trailing Shields®. Manufactured right here in the UK, we constantly strive to improve our welding technology.”
“We have been manufacturing Argweld Weld Trailing Shields® for over 45 years now right, so we can guarantee quality and 100% craftsmanship.”
It is often very challenging to carry out repair work on pipes containing liquids. One option to carry out this maintenance is to completely drain the system, which can prove costly.
Pipe Freezing Experts Huntingdon Fusion Techniques HFT® has introduced the Qwik-Freezer™ Systems to their Pipestoppers® Division. These systems use CO2 to create ice plugs or freeze seals in the pipes, avoiding the requirement to completely drain down systems.
Luke Keane, Technical Sales Manager for HFT® said: “Temporarily isolating the water in a system with CO2 Pipe Freezing Qwik-Freezer™ allows for repairs or modifications to be made without draining or shutting off the system, saving time, wastage and is quick and easy.”
A specially designed jacket is wrapped around the pipe at the point where the freeze is required. A nozzle on the jacket is then coupled to a cylinder of liquid CO2 by means of a high-pressure hose. When the liquid CO2 is injected into the space between the Qwik-Freezer™ jacket and pipe, it immediately reduces the temperature inside the Qwik-Freezer™ jacket to -78ºC (-109ºF) and this is transferred rapidly to freeze the pipe contents and thus seal the volume.
When welding reactive metals such as titanium, zirconium and nickel alloys, it is important to monitor the oxygen level before, during and after welding especially in industries where tubes and pipes must be free from oxidation with no metallurgical defects.
Weld Purging Experts Huntingdon Fusion Techniques HFT® have designed and manufactured the PurgEye® 600, an all in one Weld Purge Monitor®, which reads from atmospheric level of oxygen (20.94%) down to one part per million (0.0001%).
Georgia Gascoyne, CEO for Huntingdon Fusion Techniques HFT® said: “Possibly the greatest feature of the PurgEye® 600, apart from its total measuring range, is our revolutionary PurgeNet™, which can connect together smart accessories such as a visual warning alarm in case of rising oxygen levels.”
Diamond Wheel Tungsten Electrode Grinders are recommended for all tungsten electrode grinding. Tungsten is a very hard material and with the diamond wheel being a harder material it makes for a smooth grind.
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: “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.”
Chromium/molybdenum/vanadium steels need to be pre-heated prior to welding and also require a post-weld heat-treatment in order to preserve the mechanical properties. These materials can also suffer from loss of elements through oxidation, thus changing alloy balance and affecting mechanical properties. Protection can be provided through the use of specially developed weld purge systems.
Huntingdon Fusion Techniques HFT® have developed HotPurge®, an Inflatable Tube and Pipe Purging System specifically designed for use where the temperatures may reach as high as 300ºC (572ºF).
Ron Sewell, Chairman for HFT® said: “Restricting the volume to be purged is always crucial when welding tubes and pipes in order to reduce the volume to be purged. With CMV steels this is challenging as a pre- and post- weld heat treatment is necessary to prevent cracking. To prevent oxidation, the inside of piping needs to be purged continuously using a specialised pipe weld purging system as conventional purging systems will be unsuitable.”
For closure welds, tight bends, T piece joints and dome end connections, a range of low cost, single ended Weld Purging Dams is available from Weld Purging Experts, Huntingdon Fusion Techniques HFT®.
Manufactured from low vapour pressure materials, Weld Purging Dams are in use for where a conventional Tandem Weld Purging System cannot be used.
Ron Sewell, Chairman at Huntingdon Fusion Techniques HFT® said: “Even today, many companies are still allowing their technicians to spend time fabricating dams made of foam, cardboard, adhesive tape, wood and so on. Like paper, these materials contain a high percentage of moisture, which is undesirable to have in the presence of a weld.”
Supporting the backside or under side of weld joints will help prevent oxidation, eliminate re-welding and require much less post-weld cleaning.
Weld Backing Tape® available from Huntingdon Fusion Techniques HFT® supports weld roots, reducing sugaring and oxidation.
Georgia Gascoyne CEO Managing Director for HFT® said: “Low cost Weld Backing Tape® is very easy to use. By simply attaching the tape onto the root gap using the adhesive aluminium tape either side of the glass fibre centre, which keeps the weld joint free from weld tacks.”
“After welding, the Weld Backing Tape® is removed, leaving the weld free from oxidation with no back gouging or grinding required.”