Induction bending is an engineering process used to introduce bends along the length of a metal pipe. Products of induction bending may include the metal pipework used to transport oil and gas.
This article answers three questions about induction bending that you may find useful as you revise for your next continuous assessment test.
What Is Eddy Current And How Is It Generated?
The induction bending process uses an inductor ring to heat the part of the metal that is to be bent. Eddy currents are generated when an alternating current is introduced into the inductor ring, through the process of electromagnetic induction.
The metal under fabrications conducts the alternating current and this leads to the creation of a magnetic field around the metal. This magnetic field fluctuates (expands or collapses) according to the quantity of current present in the metal. Introducing a different metal into the fluctuating magnetic field, the cutting effect on the magnetic field induces current into this metal. The induced currents are what manufacturing engineers will refer to as eddy currents.
Eddy currents are named thus because they flow in a circular motion that is almost similar to the "back eddies" created when water flows around an obstacle in a tight spot.
What Is Annealing And Tempering As Used In Induction Bending?
Annealing and tempering are post-fabrication heat treatments for heated bends. The two processes are often used to restore the mechanical properties of the metal that may have been altered during the bending process. The two treatments may also be used to improve the mechanical properties of the bent metal.
Annealing is whereby the bent metal is exposed to temperatures higher than the recrystallization temperature of the metal. The heated metal is allowed to cool. Cold water may be used to accelerate the cooling process. Annealing often helps to make the bent metal less brittle, thereby increasing its ductility.
Tempering is used to counter the hardening effect that the bending process may have on a metal. It involves heating the fabricated metal to a temperature lower than its critical temperature. The metal is then exposed to still air for it to cool.
What Effects Does The Bending Process Have On Metal Pipes?
Effects of the induction bending process can either be physical or they can be mechanical. Physical effects of this process include, but they're not limited to, the following:
- A reduced wall thickness on exterior side of the bent metal
- A deformed cross-section of the bent metal
Mechanical effects of the bending process include, but they're not limited to, the following:
- Increased tensile strength
- Elongation of the metal