HFT’s weld purging with preheat

11 September 2020

In the power generation and nuclear industry, low and medium alloy steels such as SA 213 T91 and SA 335 P91 are chosen for their high strength, but are often prone to cracking during welding. Pre-heating and post-heating reduces the crack sensitivity. In order to meet the requirements of inert gas purging when temperatures exceed 200ºC (392ºF). 

HotPurge® has been developed by Huntingdon Fusion Techniques HFT®. It is an Inflatable Pipe Purging System for use with High Strength Steel Pipe Joints where pre-and post-weld heating temperatures might be as high as 300ºC (572ºF) for lengthy periods. 

HotPurge® systems are manufactured in sizes 6 to 88” (150 to 2,235 mm) and 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, without the metallurgical imperfections caused due to rapid heating and cooling. 

Once positioned in the pipe and inflated with an inert gas supply, the HotPurge® system seals inside the pipe with 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®.