Manufacturers involved in the biofuel, semiconductor, aerospace, food production and pharmaceutical industries are all concerned with handling under aseptic conditions. The presence of any debris and contamination in finished assemblies is unacceptable and quality control procedures must be rigidly adhered to.
Nowhere is this more significant than in fabrication of tubular sections of processing plant. Attention to detail here is crucial since even small installations may involve kilometers of pipework. Mistakes during fabrication can therefore be costly.
Demand for help with inert gas purging to meet the stringent quality control requirements set by fabricators has led to the development of a wide range of ancillary products. Global leader in design and manufacture of weld purging equipment is Huntingdon Fusion Techniques Ltd, a company that has specialised in meeting the requirements of end users for 35 years.
The HFT product range includes inert gas pipe weld purging equipment covering diameters from 12 to 1800 mm. It also manufactures advanced monitors designed specifically to measure and control oxygen content of purge gases used in welding applications.
Whereas early demand for high levels of weld quality came largely from the aerospace and pharmaceutical industries, current trends are towards even higher standards of weld control.
Piping used throughout the semiconductor industry requires a degree of purity that is an order of magnitude higher than that required previously. Operations have a critical need to mitigate the potential for particulate contamination since this can be devastating to today’s highly miniaturised electronic components.
Microscopic particles in semiconductor facilities, whether coming from equipment, tubing, or the various fluids used during the manufacture of silicon chips are totally unacceptable.
It now seems that even higher standards are needed in the biochemical sectors. If adequate care is not taken throughout the process, a proliferation of unwanted contaminants can devastate colonies of the desired bacteria and result in expensive rejection.
Weld Purging Equipment
Pipe sizes used in sensitive processing plant are seldom greater than 150 mm diameter. For these purposes HFT manufactures two distinct types of equipment; expandable plugs and inflatable bladders.
These are available with nylon, steel and aluminium bodies.
A central hole in the plug provides access for testing or gas admission, but may be closed when not used with a screw-on cap and sealing washer.
Surrounding each body is a flexible seal that can be expanded by applying a radial force through a manually operated wing nut on the shaft. These seals are available in a variety of materials to accommodate different requirements.
Tube diameters between 12 and 160 mm can be accommodated with the nylon body and up to 900 mm with the metal body variants.
Inflatable devices have been developed to help speed up the welding process for engineers involved in the fabrication of pipes and tube lines and assemblies up to 300 mm diameter.
This revolutionary PurgElite® product range replaces an earlier one that has been manufactured and marketed successfully by HFT worldwide for many years. It is now widely recognised as a robust, easy to use, welding ancillary that offers considerable savings in time and inert gas.
The ‘Elite’ development incorporates many advances in engineering technology and extends the size range to include purge systems as small as 25 mm.
The inflatable components employ low vapour pressure synthetic fabrics with low outgassing rates throughout and incorporate a connecting hose with a protection sleeve to resist thermal damage. Hoses used to transmit inert gas to and from the purge cavity and to provide inflation pressure are made from engineering grade nylon.
Oxygen Monitoring Equipment
Using specialised weld purging equipment does not guarantee defect free welds. Control of the oxygen content of the purge gas is crucial to success.
Several manufacturers supply oxygen monitors but generally these are calibrated to measure much higher levels of oxygen, typically 20%. Only HFT has designed and developed monitors to meet the specific requirements of the welding industry.
Following many months of field testing the company has recently introduced a revolutionary product range, the PurgEye®. Most of these are all capable of measuring oxygen content accurately as low as 10 parts per million.
To accommodate the singular needs for pristine welding of tubes and pipes the fully integrated PurgEye® 600 has been developed. This incorporates touch screen controls.
It also records all weld purge data for every weld and makes it available for downloading for subsequent evaluation as a quality control document. The '600' also has on/off switching capability for alarms or welding equipment in the event of rise in oxygen levels during welding outside pre-set limits as well as an integral electronic gas sampling pump.
PurgEye® 600 incorporates a large touch screen and measurement range is between atmosphere and 10 ppm. It includes an integral electronic sampling pump, datalogging software and integrated switching.