Rotating Equipment Induction Heat Application
Red-D-Arc’s latest customer success story highlights the benefits of using induction heating in rotating equipment applications.
A client contacted Red-D-Arc to inquire about the use of induction heating to remove a coupling hub from a motor shaft. The hub was 12 inches in diameter and roughly 4 inches thick.
The overall work scope was straightforward: the client needed to remove an old motor and replace it with a new motor. The coupling hub had to be reused, so the hub would need to be removed from the old motor and installed on the new one. Two things made this job challenging: the location and the time limit. The work was to take place on an offshore platform. Use of an open flame was not an option, as it would have led to a safety violation.
A blowout-preventer (special valve or device used for preventing blowouts on oil and gas wells) which had been stuck together for 9 years is finally separated with the quick application of a Miller induction heating system from Red-D-Arc.
In addition to the many welding heat treatment applications, our heating specialists have years of experience applying this technology in numerous applications from hydro dam maintenance to heavy equipment repair. Contact a specialist to find out how induction heating can be applied to your next challenge.
Thanks to Michael Hernandez AWS CWSR from our Houston location for providing the footage.
This article originally appeared in Connector Magazine, Fall 2020 Edition
Erectors can save cost and time by taking this welding technique in-house
Large steel erection projects commonly require heat treatment for welding because of the thick materials used in structural steel construction. Proper implementation is critical; so often this work is outsourced. The perceived level of expertise to perform this work can make the prospect of using in-house personnel daunting. However, most welding contractors are actually fully capable of performing on-site heat treatment operations.
The two primary methods for heat treating metal are preheating and post-weld heat treatment (PWHT). Preheating is the process of heating the base metal to a specific temperature prior to welding to minimize the temperature difference between the welding arc and the base metal. This process helps to reduce internal stresses that occur as substantial temperature differences between the weld and the base metal normalize, which can cause cracking and distortion. Slowing the cooling rate also allows hydrogen to escape from the weld, which minimizes the potential for cracking.
Applications and Advantages in Tank Fabrication and Maintenance
In the fabrication of storage tanks, as in most other welding applications, there are two crucial processes that storage tank fabricators must carry out to ensure the final quality and durability of the tanks. They are weld preheating and post-weld heat treatment.
Preheating involves heating the material to be welded to a particular temperature before welding. This process reduces shrinkage by minimizing the temperature between the arc and the base material. It also removes moisture, lowers hydrogen, and slows the weld cooling rate. These reduce the risk of cracking, brittle welds, and failure of the welds. Preheating is crucial for storage tanks as they are to withstand high pressures during operation.
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In welding, like in many other manufacturing and fabrication processes, the process is not complete until the necessary post-processing has been carried out. Post-weld operations are usually performed for reasons such as improving mechanical properties, relieving stress, and improving aesthetics. The two most common Post-weld operations are Post-Weld Heat Treatment (PWHT) and Finishing.
Post-Weld Heat Treatment
During welding, the welded materials are exposed to very high temperatures that can cause micro-structural changes in them. Also, residual stresses build up in welded materials when they are allowed to cool naturally. If left unaddressed, these stresses and structural changes can severely compromise the mechanical properties of a material and can lead to failure during use. To prevent this, PWHT is required for welded parts. There are two major types of Post-weld heat treatment and they are as follows.