When stainless steel, duplex steels or titanium pipes need to be welded in the process industries, they generally have to be purged of air and water vapour, in order to obtain the quality of weld demanded by such industries.
Even today, more than 40 years after high quality pipe weld systems were developed, welders are still carving crude discs out of sponge foam without understanding the characteristics of such materials when low cost, high quality products are available that save them countless volumes of time and money.
Most sponge foam products are open cell materials, which allow gas to pass through, so as fast as the inert purge gas is pushing the air out of one end of a pipe, oxygen and water vapour is entering at the other end.
Such old fashioned techniques cost companies dearly.
For example, a 30” diameter stainless steel pipe with sponge foam dams will take up to 3hours (180 minutes) to purge to a satisfactorily low oxygen level costing the Company £666 in Argon costs.
If however the company would use a professionally designed pipe welding system such as the Argweld® QuickPurge®, it would only take 7 minutes and cost £26 for Argon gas to purge below 100 ppm of oxygen.
The cost of the product is paid for in the first weld and each subsequent weld would save over £600.
For pipes above 6” diameter, QuickPurge® Systems are simply inserted into a tube or pipe, placed in position with one dam either side of the weld, inflated within the pipe thus restricting the area that is to be purged and removing the oxygen within minutes.
Some features of QuickPurge® Systems include:
- Combined purge and inflation line
- An additional gas input line, allowing extra purge gas to be introduced for extra high speed purging down to the lowest oxygen levels, which is perfect for larger diameter pipes where quality welds are required. This extra cold argon gas input is perfect for mitigating the extra heat produced by the Plasma / TIG process.
- The advanced design of the QuickPurge® System means that oxygen levels as low as 10 parts per million (ppm) can be reached every time, allowing zero colour welds to be achieved with no loss of corrosion resistance caused by oxidation.
- IntaCal® combined with the integrated PurgeGate® device makes it possible to safely inflate the systems with argon gas, for sealing and then purging the space between the dams where the weld joint is located.
- With PurgeGate®, any risk of over inflation is due to pressure or flow increase, is eliminated.
- All systems are manufactured as standard with a hose for connecting a Weld Purge Monitor®, which can read oxygen levels down to as low as 1 ppm (accurate to 10 ppm).
- Materials used in the manufacture of QuickPurge® are such that they are resistant to the higher weld temperatures present and they don't outgas, thus preventing weld contamination.
For pre-heated chrome steel and high strength stainless steel pipe joints, HFT® manufactures the HotPurge® Systems for a higher and longer temperature exposure.