CMV Steels (chromium / molybdenum / vanadium) are widely used for their high temperature creep properties especially in the steam turbine industries.
Both pre and post weld heat treatment is necessary to achieve the optimum mechanical strength, but temperatures up to 300ºC (572ºF) must be maintained for lengthy periods. To prevent oxidation, the inside of piping needs to be purged continuously using a specialised pipe weld purging system.
Huntingdon Fusion Techniques HFT® has designed and developed HotPurge® Pipe Purging Systems capable of operation at these elevated temperatures.
Weld Purging short pipe pieces and dome-end welds where tandem Inflatable Tube and Pipe Purging Systems are unsuitable, Huntingdon Fusion Techniques HFT® manufactures Weld Purge Dams.
Ron Sewell, Chairman for HFT® said: “When welding tubes and pipes, the most cost- effective solution is to restrict the volume, usually with a Tandem Weld Purging System, especially welding metals such as stainless steels, titanium and zirconium.”
“Where Tandem Weld Purging Systems are unsuitable, Weld Purge Dams are available for pipe diameters from 6 to 88” (152 mm up to 2,235 mm) and offer a low-cost alternative to foam or cardboard dams that are still frequently handmade by welders on site. Unsuitable materials can often lead to rework of some kind and in worst cases cause welds to be rejected.
Supporting the liquid weld root with a high temperature Backing Tape will ensure minimal oxidation and will require much less post-weld cleaning.
Argweld® glass fibre Weld Backing Tape® from Huntingdon Fusion Techniques HFT® supports weld roots and eliminates the creation of slag, whilst removing contact with air to dramatically reduce the amount of contamination.
Ron Sewell, Chairman for HFT® said: “Available up to 600 amps, our 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.”
When welding long pipelines, one problem operators often face is not receiving a fast and true weld purge reading from the weld zone.
Huntingdon Fusion Techniques HFT® make it possible to have an immediate reading of the weld purge gas from any distance up to 1,000 metres away with the PurgEye® 1000.
This unique Weld Purge Monitor® has a stainless steel sensing head that can be fitted onto any Pipe Weld Purging System or simply left in the welding zone and have the oxygen levels transmitted electronically to a monitor up to 1 km away.
Lightweight Inflatable Rubber Plugs are available from the Pipestoppers® Division at Huntingdon Fusion Techniques HFT® for sealing, stopping and blocking pipes where oils, hydrocarbons and petrochemicals are present.
Challenging pipe stopping conditions can cause major inconveniences but many alternative products are not able to handle such situations.
Luke Keane, Technical Sales Manager for HFT® said: “Our Rubber Plugs are manufactured from high quality materials, ensuring a long life span of each Plug. They serve many purposes for a range of different industries and are highly resistant to oils, hydrocarbons and petrochemicals.”
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 tightening of the ring nut that expands a rubber ring and make a completely leak-tight seal. In addition, because the plugs are neutrally buoyant they can also be used in sub-sea environments.
Standard plugs are fitted with a natural rubber seal, but alternatively silicone, nitrile, neoprene or Viton can be supplied if required.
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 cost, hand held, battery operated PurgEye® 100, designed and developed by Huntingdon Fusion Techniques HFT® is perfect for obtaining zero colour, oxide free welds in stainless steel, reading accurately from atmospheric oxygen level (20.94%), right down to 100 ppm (0.01%).
The PurgEye® 100 is IP65 rated and comes with long life sensor, leak-tight push buttons, auto calibration and a vacuum-sealed leak-tight probe assembly. The monitor has a clear, easy to read LCD screen with features such as a low battery icon as well as the low sensor icon. When the monitor is not in use, an automatic sleep mode activates to conserve battery life.
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 oxygen.
The Pipestoppers® Division of Huntingdon Fusion Techniques HFT® manufacture a range of low cost, lightweight Weld Purge Plugs for a variety of applications where the pipe sizes are 0.5 to 6” (12 to 150 mm) diameter.
Ron Sewell, Chairman for HFT® said: “Our Weld Purge Plugs are a great barrier for purging pipes when welding alloys and stainless steel. Manufactured with a hollow shaft, these plugs can be used for weld purging smaller diameter pipes and miscellaneous stubs.”
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 weld in just minutes, available from 1” (25 mm).
Ron Sewell, Chairman for HFT® said: “Without restricting the purge zone with an inflatable pipe purging system when welding stainless steel, titanium or zirconium tube and pipes, displacing the oxygen in entire pipelines with an inert gas (usually argon), can cause a lot of wasted time and gas. PurgElite® reduces argon use and increases weld production.”
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 Fusion Techniques HFT®’s blue-tipped MultiStrike® Tungsten Electrodes contain a mix of rare earth stabilizing compounds without thoria and are thus radio-toxic free. They also offer a life extension of up to ten times that of other stabilized electrodes.
Each packet comes with a traceability number to ensure that companies with a quality control procedure have traceability over another aspect of their joining processes.
Pipe blocking and stopping pipes containing hydrocarbons such as petroleum products and natural gas can often pose challenges, with normal Pipestoppers unable to withstand such intense conditions.
The Pipestoppers® Division of Huntingdon Fusion Techniques HFT® manufacture a range of hydrocarbon resistant stoppers called PetroChem® Stoppers. Manufactured from a high-grade latex, the PetroChem® Stoppers offer a rubber internal inflatable bag covered with a petrochemical resistant layer, which has a tough, woven impregnated nylon outer cover, capable of withstanding temperatures up to 80ºC (176ºF).
Ron Sewell, Chairman for HF® said: “Inflatable Stoppers are often used for various applications such as debris stopping, leak testing, low-pressure hydrostatic tests, blocking the release of hydrocarbon gases and a variety of plumbing operations.”