SAFETY IN BUTT WELDING
A recent tragedy in Australia on an imported welding machine has focussed local attention on the safety aspects of automatic welding equipment. As one of the world’s most committed operator health and safety nations; Australia has taken this very seriously.
Operator error is an interesting concept when applied to such accidents, as is the case with motor vehicles. It was not long ago when cars were not fitted with airbags, ABS brakes, impact resistant design, safety steering columns, even power brakes and power steering. Some cars in 2014, park themselves, and soon will be automatically driven using mobile PLCs. In the ‘70s they didn’t even include seat belts, but of course they are standard now.
Today’s Equipment Options:
Todays’ automatic welding equipment design offers a myriad of options to increase the safety of operation. Proxy switches, two-handed operation, inspection cameras, dead-man switches, CAT3 safety shutoff, safety signage, restricted entry space, hydraulic hose wrap and so on.
Which options are applied to equipment comes down to price, and training. Historically, butt welding has been trained generically. Whether it is a 5 day comprehensive DVS course limited to 630mm pipe diameter; an Australian two-day course covering butt welding and electrofusion; or a quick visit by the salesman showing the basics - cross-training and certification has been deemed satisfactory, and probably is, for generic ‘European style’ equipment. This type of equipment has separate components located in the working area, and is the most commonly used. It is also the safest.
For many years another style of equipment has been used in North America, where all components of the machine are fitted in a single assembly. This assembly can be machine only, on a wheeled carriage, or on tracks with its’ own generator. These machines are very handy for long pipelines, or where the welding location will be often relocated. They also have the highest capital cost, so the value equation is up to the location, contractor, available human resources etc.
Considering machine design, traditional butt welding machines have used basic and proven hydraulic design. For top-end machines some manufacturers, including Australian butt welding manufacturer; Worldpoly, use mobile PLC controls to provide the relevant control of pressure, time and temperature. More recently such controls have also been applied to the automatic operation and measurement of drag, heating plate changeover, welding and cooling pressures and times, data logging and remote communication.
Until recently, the single-unit machines have relied on basic controls as have been successful in various modifications for decades. What has been clearly lacking is the use of current technology in not only the welding operation, but operator safety.
New developments in Operator Safety
Three years ago Worldpoly began a dedicated research and development project with international leader Bosch Rexroth resulting in a quantum leap in butt welding machine design and operation; using leading edge automation technology. Rexroth embraced this new opportunity and enthusiastically brought their Australian, European and US intellect to the party, resulting in Worldpolys’ PolyForce630 Automated butt welder.
Unlike other machines, PolyForce630 uses Rexroths’ Mobile PLC, the same unit used on underground rock drills and excavators. As an almost indestructible controller, this allows the provision of safety and welding controls previously unavailable.
From an operational perspective, it is not possible to crash the heating plate and facing tool with the pipe clamps, and changeover time for 630mm (24”) SDR 11 is consistently 3.5 seconds.
