Heat treatment by Red-D-Arc works best in steel erection projects

Red-D-Arc offers various heat-treatment options.

Red-D-Arc Welderentals rents and sells various equipment for preheating and post-weld heat treatment. (PWHT). These techniques are important in large steel erection projects, due to the thick materials in structural steel construction, and proper implementation is vital. Although this work is often outsourced because of a commonly perceived level of required expertise, most welding contractors can perform these operations onsite. Erectors can save time and money by heat-treating metals in-house.

The difference between the methods

Preheating means the process of heating the base metal to a desired temperature before welding to minimize the temperature difference between the welding arc and the metal. This process helps reduce internal stresses. Preheating requirements for steel depend on the steel’s chemical composition, section thickness, the process employed, and diffusible hydrogen. PWHT operations are typically conducted to improve mechanical properties by minimizing hardness, increasing ductility, and relieving weld-induced stresses.

Relying on service providers for heat treatment can raise costs by up to ten times. Although some applications many be too complex for beginners, most are easy and straightforward. With proper equipment and assistance from an experienced technician, basic heat treating is even simpler than welding. Performing this process in-house saves significant time and costs.

Open-flame heating is a simple method, but comes with safety risks and can be inconsistent and inefficient. The two top alternative techniques are induction heating and resistance heating. Induction heating uses non-contact heating to induce heat electromagnetically, so the weldment becomes its own heating element. This method of heat treatment works only with magnetic material, though. Resistance heating involves electrically heating a wire passing through flexible interlocking ceramic heating elements, typically called beads or pads. This technique can achieve temperatures higher than 1,000 degrees Celsius with standard heating elements.

For a highly portable, field-construction induction-heating system, Red-D-Arc recommends its Miller ArcReach Induction Heater. This unit has a small footprint and built-in data recorder. The Miller ProHeat 35 is the industry standard for larger induction-heating tasks; it is also ideal for preheating large columns and bridge girders. Also available from Red-D-Arc is Stork Cooperheat equipment for PWHT.

For more information, contact Red-D-Arc.

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