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).
Manufactured in sizes 6 to 88 (150 to 2,235 mm), HotPurge® Systems can be used repeatedly for weld purging and can keep the oxygen levels below 100 parts per million (ppm) throughout the welding cycle, ensuring oxidation-free welds and eliminating metallurgical imperfections caused by rapid heating and cooling.
Once positioned in the pipe and inflated with an inert gas supply, the HotPurge® System seals inside the pipe with the inert gas supply displacing the oxygen from within the weld purging zone ready for pre-heating and welding. Each HotPurge® System is manufactured with a Weld Purge Monitor® connection for viewing the oxygen level throughout the welding process.
Courtesy of Huntingdon Fusion Techniques HFT®.