Induction heating has long been used in a number of industries for more traditional applications, but it is a fairly new technology to be employed in welding. Recently, it has become more and more common to find it being used in both construction and industrial welding processes.
In welding, induction heating allows for direct preheating of the specific point where a weld will be placed. For post-heating, it provides stress relief for the weld site. Because the heat does not directly touch the metal, it heats from within – much like a microwave – via electromagnetism.
The high-frequency electromagnetic field induces eddy currents to the weld site, which generate heat and excite the metal’s molecules. Frequencies of the field can be manipulated to produce heat to precise depths from the surface of the material being welded. This process eliminates the need to heat the entire thickness of the metal, and no heat is wasted by using this method. This translates to enhanced energy savings and far more structurally sound welds. The reliability of induction heating equipment means fewer repairs and greater cost savings to companies as well.
On large welding projects such as high-pressure steam pipe, the complete heating cycle time for preheating and stress relief is reduced by a few hours. When other usability factors are combined with induction heating in welding applications, it is possible to obtain a 50% time savings on each cycle.
When preheating or stress-relief processes are being performed in welding, it is vital that these processes are not interrupted until complete if the weld is to be strong and sound. Induction heating equipment rarely, if ever, has incidences of cycle interruption, making it is one of the best tools utilized for welding today.
Not only does induction heating allow more efficient pipe-welding applications, it is just as effective for metal parts of all shapes and sizes that must be welded. The welder is able to control the entire heating process from start to finish, with results producing the highest-quality welded seams.
Induction heating for welding is not only used in various pipe-welding processes and for metal parts, it can also be used in other large-scale operations, such as repair and maintenance of mining equipment and in building and maintaining heavy equipment used in the construction industry. Repairs and maintenance that require pre-treatment before welding can now be easily performed on the job. Previously, heavy construction parts and equipment had to be moved to other locations for repair.
The growing oil-and-gas market has reaped the benefits of induction heating in welding, particularly when it comes to repairs to large-circumference-diameter pipes already in use. The safety and precision of induction heating technology eliminates the need to stop the flow of oil or drain any pipes prior to their repair.
Preheating with induction is critical in applications where the temperature must be precisely controlled to increase the life of the part, such as oil-and-gas pipe. This also reduces the weld time, with better results and improved uniformity being obtained. Welding repairs place less stress on pipe materials because the heating process takes less than half the time of traditional methods.
Charlie Parsana is the project engineer at Electroheat Induction of Jersey City, N.J. Electroheat Induction is a leading provider of high-quality, custom induction melting furnaces, induction heating and hardening equipment, and pipe heating products.