TPT September 2020

T UBE WE LD I NG MACH I NE S & T E CHNOLOG Y

The benefits of using seam annealing equipment to ensure a perfect weld seam

the set point and, depending on the situation, the power reference can be increased or decreased using the PID to meet the temperature requirement. The high reliability, ease of maintenance and the energy saving of the entire EMMEDI family of products, which are industry 4.0 compliant, have led to it being a success worldwide, the company stated. Its partnership with Ajax Tocco has secured the EMMEDI brand as a steady presence in the market through widespread technical support, global solutions and after-sales services from numerous international locations.

The smart control desk is equipped with a touch screen industrial PC. Operators can use this to download production data, store ‘recipes’ and guarantee excellent production results. The seam annealing equipment is also equipped with pyrometers at each seam head, which are the process temperature/power guards of the Medium Frequency IGBT converters. The pyrometers are connected to converters thanks to the Proportional- Integral-Derivative (PID) controller. The analogue signal coming from the pyrometer, together with a pre- determined feed-forward value, is used to control the power converters according to the required temperature. The actual reading is compared with

OVER the pasts 50 years EMMEDI has earned an excellent reputation in the tube and pipe industry due to ts experience in the design of technology used to manufacture EMMEDI induction systems. This experience is also evident in its seam annealing equipment. The seam annealing process is dedicated to the normalisation of the Heat Affected Zone (HAZ) as the welding bonding line is modified from a metallurgic point of view and it can generate failure in flattening and flaring tests. Both the American Petroleum Association (API) and the American Society for Testing and Materials (ASTM) specify that on certain grades of pipe, the weld seam needs to be processed in order to ensure that no untampered material remains. To remove the unwanted martensite, the weld must be reheated by a seam normalising, or seam tempering, process. The distance of the inductors should be between 6-10mm from the HAZ and each heating unit equipped with two water cooled rolls preventing dangerous contact with the tube. After the process the tube must be cooled down in a free atmosphere and then, when it gets to 370°C or lower, it can be cooled down further by water shower. Inductors are linear with a maximum width of 40mm and maximum length of 1,200mm bars of copper covered by magnetic flux concentrators cores to more effectively focus the magnetic field on the tube seam area. One inductor can relive maximum 600kW. The main features of the seam annealing equipment designed by EMMEDI are robust and efficient IGBTs technology and inductors with new flux-concentrators that guarantee great performance (process temperature 950 to 980°C at 1 to 3kHz are a typical working frequency). In addition, the manual – or automatic – seam-tracking system keeps the inductor on track on the HAZ in tilted conditions (+/- 15° on the vertical axis) of the bonding line. Thanks to the great smart process control system it is possible to control both equipment and the process.

EMMEDI www.saetemmedi.com

The EMMEDI seam annealing equipment

67

www.read-tpt.com

SEPTEMBER 2020