ZM150 Degauss controller for Zeromag
Zeromag measures and neutralizes magnetic fields which may be present in the weld preparation region of mating steel components. When welding pipes there are several ways of working. In normal operation, Zeromag is used to dynamically reduce the magnetism during welding. This works well but having demagnetizing components in place while welding can hinder welding throughput.
The ideal would be to degauss all the components completely, but the process is too long and cumbersome. There are also issues with penetration of ac degauss fields into the bulk of the material, leaving the core still magnetized.
The Zeromag degauss option undertakes degaussing of the complete fitted up butt joint. In this mode of operation cable is wound over the pipe butt joint (usually with clam coils) and a quick downcycle initiated. With the joint degaussed the coils are removed and welding can commence. Magnetism can return either over time or as a result of the changes in magnetic geometry as welding progresses. If this occurs the demag procedure can simply be repeated.
The joint degaussing can be extended to pipe end degaussing. In this mode, the Zeromag degauss option undertakes degaussing of the end of the pipe only prior to fit-up. This down cycling process is relatively quick – typically less than 3 minutes. The hysteresis loop time is typically 10 seconds allowing deep penetration of the degaussing field into the steell of the pipe end. The magnetism in the rest of the pipe remains unchanged, so, over time, the magnetism in the rest of the pipe will ‘leak’ back into the pipe end. This process is material dependent, but is typically about 1 hour.