The main goal of the tube annealing processes is the hardness decreasing (black and bright annealing) and the normalization of the Heat Affected Zone (seam annealing).
In case the process is applied to bright annealing systems, the tube is heated for a shorter time than in a traditional furnace, then a partial solubilization of chromium carbides is obtained. In addition to this, the use of protective atmosphere (mainly pure hydrogen) allows for improvement of surface characteristics and resistance to corrosion.
This is a fast and precise process, with no warm up time. It is applied to stainless steel, duplex and titanium tubes.
The seam annealing process, mainly applied to API tubes, consists in the heating of the seam beam and it is cooled down at ambient temperature. Flexibility is maximized by using multiple independent heating heads, each one individually controlled.
Induction heating is the preferred solution for tube and pipe manufacturers looking for more effective, cost-efficient heating technology.