Welding

The EFD Induction Weldac: What it is, how it works and why you should care. ‘Weldac’ is EFD Induction’s range of solid-state welders for tube and pipe welding. A standard Weldac system comprises a diode rectifier, IGBT inverter modules, an output section, busbar and operator control section.

The article investigates the impact that geometrical changes in the weld zone have on weld frequency and the Heat Affected Zone (HAZ). The article evaluates the consequences of controlling HAZ by a variable frequency option. The article points out the importance of weld setup control.

The authors evaluate the parameters that influence welder performance and scrap production during changeover in the high-frequency tube and pipe welding process. The paper focuses on the welder system’s features during changeover. The parameters involved are welder recipes, energy consumption monitoring, and matching capabilities.

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.

The authors evaluate the parameters influencing weld quality and scrap production in highfrequency tube and pipe welding. The paper focuses on the welder. Two stages of the production process – steady state operation and non-ideal conditions – are investigated. The parameters involved are ripple in output power and short circuits in the load.

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.

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.

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.

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.

Temperature distributions in the cross-section of the weld point are calculated through two-dimensional coupled electromagnetic and thermal FEM analyses.

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.