Flame-less welding as safer option

Each sheet undergoes a large-scale flame treatment with a Bunsen burner. The overlapping sheet is then pressed onto the fused lower sheet. This is a method fraught with risk as the thermal insulation located below the seal or the flammable roof substructure can catch fire. As a result, more and more building owners are prohibiting the use of an open flame for safety reasons.

Tyson Foods Inc. (TNI), with headquarters in Springdale, AR, is one of the world's largest processors and marketers of chicken, beef and pork, as well as prepared foods. The roof of Tyson Foods’ Noel production facility, had become quite old and was replaced. Although the roof was to be sealed with bitumen sheeting, the building owner specified that no welding was to be performed with an open flame on the roof as such process entails risks.

Approximately 600 square metres had to be newly sealed as quickly and neatly as possible. When it came to the sealing material for the massive roof area the decision makers opted to use bitumen, but only under the condition that open flame would not be utilised during the roofing work.

Proven solution found
Harness Roofing is a renowned commercial roofing company in the state of Arkansas. The company was approached by Tyson Food with its specific requirements. Such specification did not pose a problem for Harness Roofing as it knew of a welding tool in its range that welds bitumen sheeting with hot air instead of an open flame, the Bitumat B2 from Leister Technologies AG (www.leister.com).
Harness Roofing had already been working with Leister's range of handheld tools for many years. Leister’s top selling hand tool, the Triac S, and the more powerful Electron have been used for detailed welding at Harness Roofing for decades. However, open flame was still used for large area welding. Tyson Foods' specifications required that Harness Roofing abandon this method for this project. With the Bitumat B2, Leister was able to offer a hot air welding machine that met all of Tyson Foods' requirements. Bitumat B2 is a high speed flameless automatic welding machine for welding modified bitumen (SBS, APP). It produces a significantly better weld strength and is more economical and safer to use than open flame welding.

Tremendous productivity and efficiency Harness Roofing accepts nothing short of optimum quality standards. To satisfy this requirement, the selection of the right tool and a well-trained workforce were top priorities to the roofing contractor. Leister offered both.

After the inaugural attempts on the roof, it was clear to the roofing contractor that the work with the new hot air machine not only offered an alternative to an open flame but actually represented the ideal solution in every respect. The high-performance nozzle, specially developed for working with bitumen, enabled a working speed of nearly 7 metres per minute. Requiring only one person to operate the Bitumat B2 combined with the high working speed translated to higher productivity.

The Bitumat B2 is designed with an integrated air dam - rotating rubber belt located between the drive and pressure roller - ensuring that the bitumen sheet is pressed downward during the welding process, whilst the controlled hot air volume is routed between the bitumen sheets. The use of this feature results in consistent, uniform weld seams. Furthermore, the air dam better focuses and traps the air precisely where it is needed, preventing the burning of the underlying thermal insulation. In controlled peel tests, the Bitumat B2 achieved more consistent results when compared with welds achieved with a torch. The height-adjustable handle of the Bitumat B2 makes maneuvering the machine during the welding procAir Jordan