Some of the great properties of nickel alloy 800H tubing that make it appropriate for certain uses can also make it hard to deal with. One of the problems you may encounter is welding. Because of its ability to withstand high temperatures, it may be hard to weld.
If care is not taken as you weld nickel alloy 800H tubing you may end up with a few defects which include crevices, surface oxides that result in corrosion, arc strikes, and removal of protective film on the metal among other problems, these can be prevented by using the right procedure.
Qualification and Training
Whoever is working as a welder for nickel alloys must have the right qualification and training. Each country may have its own certification standards that would qualify someone to work safely and effectively on this kind of metal.
Training will cover the different methods used to weld alloys as well as preparation for welding among other important information concerning welding and fabrication. At the end of the training, the individual will have to pass a test to qualify as a welder.
Methods Used to Weld Nickel Alloys
There are mainly 3 methods commonly used to weld nickel alloys, these are:
– Gas tungsten arc
– Shield metal arc
– Gas metal arc
Gas Tungsten Arc Welding
This is a commonly used procedure for welding nickel alloys. Agon gas or any inert gas is used to protect the metal from the air, meanwhile, the filler metal is added into the arc. This can be done automatically or manually. The thickness of the metal doesn’t matter in this process. The advantages of GTAW include:
– It is effective when welding pipes.
– Slug residue is minimized so clean up after welding is not much.
– It does not cause alloy loss.
– It is neat with minimal or no finishing needed.
Shield Metal Arc Welding
SMAW is appropriate when dealing with shapes that cannot be welded automatically. The entire process is manual as the welder constantly controls the arc. Because of the versatility when using this technique, there are many ways to perform it depending on the type of nickel alloy being used. Care needs to be taken when welding and it is best to have a helper as you do this.
Gas Metal Arc Welding
With this technique, an arc is created between the piece, bare wire electrode, and consumable. A gas shield is then used to protect from external air. Either helium or argon can be used and at times a combination of the 2 can work as well. Carbon dioxide can also be added for bead control. Advantages of this process are:
– Automation is easily achieved.
– Welding can be done faster.
– There is a proper transfer of elements between the arc.
– Produces no slug so there is no cleanup needed.
Conclusion
Because nickel alloys are used often in applications that require error-free performance, it is important that the people who execute the welding know exactly what they are doing. It is best not to try and fiddle with it on your own if you haven’t received the right training to carry out the task. At the same time, ensure that you have the right nickel alloy.