Alloy 20 pipes and flanges are used in many industrial settings because they are strong and highly resistant to acid. They are also resistant to something else: welding. The combination of chromium, nickel and stainless steel in alloy 20 pipes and flanges makes them notoriously difficult to weld. Pieces can be bonded together with gas tungsten arc (GTA) welding, though. Here are two tips for making welding alloy 20 pipes and flanges together a little easier.
Take Your Time
The mixture of different metals in alloy 20 makes it less conductive than other metals that are used in industrial applications, such as stainless steel. Because the alloy doesn't conduct heat as well, it takes longer for an alloy 20 pipe to heat up.
When welding alloy 20 pipes or flanges, you need to compensate for its lower thermal conductivity by going slower. If you yourself are welding alloy 20, take your time. If you oversee welders who are working with alloy 20, be sure to allot them plenty of time to do the job properly. For, going too quickly will produce uneven heating and leave cold shuts where the metals didn't fuse properly.
Use Moderate Heat
It may be tempting to speed up the welding process by increasing the heat, but high temperatures can distort an alloy 20 pipe or fitting in two ways. First, the parts of the pipe directly exposed to the welding arc will quickly become extremely hot. The areas that aren't directly exposed to the arc will also heat up faster, but the disparity between hot and cold areas will be larger than it ought to be.
Second, high temperatures will affect each of the metals in alloy 20 differently. Increasing the weld current so that it produces a lot of heat can destroy the alloying elements, especially the chromium. This weakens the metal and makes it more susceptible to corrosion.
As you weld, you can make sure the arc doesn't become too hot by watching for a color change. If the arc becomes too hot for the metal, it will change colors. This is a sign that the arc's causing alloys in the metal to react, and you need to lower the arc's temperature.
Welding alloy 20 pipes and flanges requires a little extra time. As long as you don't rush the process, though, they can be successfully welded together using GTA welding. The next time your company needs to weld alloy 20 pipes or flanges, be prepared to take your time and resist the urge to turn up the heat. The end product will be a well-bonded pipe or fitting that's suited for years of work in an industrial setting.
To learn more about alloy 20 pipe, contact a company like James Duva Inc.