TPT May 2008

T ube & P ipe W elding: T rends & P rogress

Breakthrough for welding small diameter, thick wall tube

Several producers of small diameter, thick wall tubing have installed Thermatool variable frequency welders to optimise production of this ‘difficult to weld’ tube. The welders are extremely beneficial as they offer the ability to start at a higher weld frequency and then to reduce it to a point where the most desirable weld properties are obtained. Alternatively, the weld frequency can be reduced to just above the point where the impedor starts to lose its magnetic properties. The Thermatool range of selectable variable frequency welders greatly assists the unique characteristics of each tube mill and/or weld setup. Thermatool Corporation – USA

Often considered the hardest tube to weld, many producers simply have no option other than to apply excessive weld power in order to achieve a weld. One major disadvantage here is that excess power dissipation within the weld zone will inevitably turn the tube blue, significantly reducing its market value or turning it into scrap. Applications for small diameter, heavy wall mechanical tubing continue to increase, particularly in the automotive, recreational vehicle, farm and garden machinery market sectors. Commercial considerations are such  Thermatool provides advanced variable frequency welding technology

that this type of tube needs to be produced at economically viable mill speeds. The advent of a genuinely selectable, solid- state variable frequency welder has been a major breakthrough, facilitating higher mill speeds and a significant increase in production yields. To achieve increased productivity the weld conditions must also be optimised. This will require the correct selection and positioning of both work coil and impedor. With the welding of small diameter, thick wall tube, sufficient power must be transferred to the weld vee to obtain a quality weld. Due to physical size limitations, only a small diameter impedor can be used. A weld frequency of 400kHz is generally accepted to be best suited for the production of carbon steel tube where the diameter to thickness ratio is equal to or greater than 4:1. However, the weld quality can be significantly improved by varying the weld frequency with the added benefit of the inside weld bead becoming less pronounced. (100kg) or 440lb (200kg) capacity mini-positioners can help improve weld quality and increase production. The positioners feature an 8-slot turntable that tilts from 0-120º and provides quick mounting for holding fixtures. The spindle has a 1.38″ through hole for pipe work or gas purge. The company’s turning rolls have a remote foot switch with run/stop controller, and a forward/stop/reverse switch with potentiometer for stepless speed adjustment.

Fax : +1 203 468 4281 Email : info@ttool.com Website : www.thermatool.com

Thermatool IHWT – UK Fax : +44 1256 467224 Email : info@ihwtech.co.uk Website : www.inductotherm-hwt.co.uk

Flange welding made easy Bug-O Systems, USA, now offers positioning, turning rolls, manipulators and torch oscillators for pipe and flange welding automation. The company’s new line of 220lb

Bug-O Systems’ manipulators are manual or motor driven and include pendant control with DC driven drive and optional arc sensing height control. The company’s torch oscillators can perform weave welds or straight-line stinger welds, and feature adjustable independent dwell settings.  Bug-O Systems provides equipment for pipe and flange welding

Bug-O Systems – USA Fax : +1 412 331 0383 Email : jwhite@weld.com Website : www.bugo.com

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M ay 2008

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