WELDING equipment from Leister Process Technologies, a global leader in the fields of plastic welding and hot-air blowers, was again put to the test in the Gulf’s harsh climatic conditions.

The welding machines and hand tools from the Swiss company were employed in the waterproofing works at the Qatar National Convention Centre (QNCC), one of the world’s largest construction projects, currently under way in Doha, Qatar.

About 135,000 sq m of Sikaplan WP1100-20HL2, a 2-mm polyvinyl chloride (PVC) geomembrane produced by speciality chemicals manufacturer Sika, were laid as a single layer for the mega project – a scale that posed a great challenge even for the waterproofing installation company BMC Qatar, especially since the work was needed to be completed within a year, according to Roland von Ah, key account manager at Leister, Switzerland.

In a bid to tackle this challenge, professionals at BMC Qatar relied on Leister’s welding equipment. “Good equipment is the key to success,” states Hani Fikry Zaki, Sika project manager. “The Leister machines kept welding and impressed us once again with their high welding speed, especially under hot, humid and dusty conditions during summer, when temperatures in the region reach over 50 deg C.”

Four Twinny S and two Twinny T combi-wedge welding machines from Leister were employed on the project. “Optimum welding seams were attained using combi-wedge technology, where the welding seam is heated only where actual welding occurs. Additionally, the use of hot air removes dust from the seam, providing an optimal surface before welding,” explains von Ah.

He continues: “The design of the regulated Twinny T incorporates a digital display, which denotes both temperature and welding speed. Despite being lightweight – just 6.9 kg – the machine can reach a welding speed of up to 3.2 m per min, depending on the material.

“At the QNCC, a total of 80 km of membranes were welded with a double weld seam, consisting of two 15-mm weld seams and a 20-mm-wide test channel. After the membranes were welded together, the channel was used to successfully test the leak tightness with compressed air using a Leister testing device, featuring an injector needle.”

In addition, about 100 km of welding seams were produced with 16 Triac S hot-air hand tools and two Triac Drive PID semi-automatic welding machines. “The Triac Drive PID is actually a hot-air hand tool outfitted with a drive motor that can be used to weld less accessible areas – vertically, horizontally or diagonally) – more quickly and hence more productively,” says von Ah. “The two Triac Drive PID welding machines were used especially for the waterbars, while the Traic S hot-air hand tools were used for edging and reinforced foundation supports.”

Upon completion, the 100,000-sq-m QNCC is expected to host regional and international conventions, exhibitions, gala events, concerts, weddings and banquets. The modern four-storey building incorporates a three-storey basement car-park. Six Construct-Midmac JV is the main contractor on the project.

BMC Gulf is Leister’s exclusive sales and service partner for the Middle East.