Maximizing uptime in high-frequency tube and pipe welding
This article explains some basic principles of solid-state welder design that are crucial for maintaining operation under various conditions. The paper also presents several key differences between MOSFET and IGBT transistors, and describes how a converter with a voltagefed inverter and series resonant output circuit withstands short circuits. More about high-frequency tube and pipe welding
Introduzing a control solution for weld seam normalizing
EFD Induction has unveiled a new control system for normalizing pipe weld seams to API standards. Per H. Ødesneltvedt, one of the R&D engineers involved in the project, explains some of the system’s features and benefits. More about the control solution
New HF converter for induction heating
This paper presents a new HF-converter for induction heating. The converter has a diode rectifier and automatic matching. It uses a patented timesharing principle for high frequency use of IGBTs (ref. [1]) in order to reach 350 kHz. The paper focuses on the benefits the converter structure has in some typical application. More about new HF converter
Factors influencing heavy wall tube welding
Introduction
Induction welding of tube and pipe with increased wall thickness presents manufacturers with new challenges regarding production rates and quality. In a medium- and thick-wall tube the heat-affected zone (HAZ) is shaped like an hourglass, ie the corners are heated more than the centre of the tube walls. A cold centre can limit the maximum weld speed, even if the mill has additional capacity and the welder has additional power.
Compensating with more power to sufficiently heat the cold centre can overheat the strip edges considerably. Weld quality can deteriorate and the overheated edges may cause molten material to drop onto the impeder, reducing impeder lifetime and performance. To understand this weld problem better, we have studied parameters influencing the temperature distribution across the weld. These parameters are Vee angle, distance from weld point to induction coil, spring back, weld speed and frequency. More about heavy wall tube welding
Optimization of seam annealing process with the help of 2D simulations
In the production of welded pipes according to API standards, a normalization of the weld and heat affected zone (HAZ) is required. The weld of thick-walled tubes shows an hour-glass shaped HAZ caused by the ”corner effect” in the weld Vee. The microstructure, particularly at the external and internal surfaces, is very coarsegrained. The aim for the heat treatment is to reestablish a homogeneous and finegrained microstructure in the HAZ. More about seam annealing process
Computation and analysis of temperature distribution in the cross-section of the weld Vee
Temperature distributions in the cross-section of the weld point are calculated through two-dimensional coupled electromagnetic and thermal FEM analyses. A specific development, using FLUX2D, has been done in order to take into account the tube walls’ movement towards each other as they approach the weld point. More about computation and analysis
Temperature Evaluation of Weld Vee Geometry and Performance
The heat affected zone (HAZ) in a medium– and thick-wall tube is shaped like an hourglass. This can give overheated corners and a cold center in the tube wall, which limits weld speed. A parameter study of the influence of Vee angle, spring back, weld speed and frequency is carried out. Two-dimensional, coupled electromagnetic and thermal FEM analyses give the temperature distributions in the cross-section of the weld point. The results are presented as isothermal lines at the weld point. More about temperature evaluation