Graeven: Metal technology for the most stringent requirements in the world

In the last five years a gigantic astronomical project has been realized in the Atacama Desert in the North of Chile: Alma – Atacama Large Millimeter Array. The international research project made up of US-Americans, Canadians, Europeans, Japanese and Chileans set up about 66 radio telescopes on the mountains of the driest desert in the world, at a height of 5,100 meters. Alma is currently the world’s most expensive and largest project in ground-based astronomy. It is expected to be completed this year. The area is particularly suited to observation of the sky because of the extremely dry desert climate. But the temperature differences of 30 degrees during the day and minus 15 degrees at night present enormous challenges for the materials used for the radio telescopes.

These challenges bring the company Graeven Metall-Technik GmbH in Tönisvorst into play. This small family-owned business specializes in the processing of stainless, acid and heat-resistant high-grade steel, special metals such as Inconel and Hastelloy as well as special materials such as titan, zirconium and niobium. Graeven supplied many mounting bracket and connectors for 25 radio telescopes from the Tempelshof business park in Viersen district to northern Chile on the Pacific coast. “It’s not easy finding good apparatus engineers,” the company’s founder and managing director Jochem Graeven says. Word quickly got round about his company, which he founded in 1984. There are only a few rival companies for him across the whole of Germany, across Europe, for that matter. The order books are full; the 25 employees in Tönisvorst have plenty to do.

Now the company has just received a new permit for salvage pressure receptacles in line with EU law – as the first company in Europe to do so. Graeven has grown constantly from small beginnings, but has always kept its feet firmly on the ground. With orders for wastewater treatment plants and major accounts such as Schloemann Siemag (SMS), Graeven Metall-Technik has grown steadily from year to year. The company also profited from German unification. Since there wasn’t a system in place for wastewater treatment in the new German states, master engineer Graeven developed and supplied mobile wastewater treatment plants in containers there together with an engineering office in Dinslaken. But the boom didn’t last long, for manufacturers in Poland and the Czech Republic began producing at a lower cost.

When an apparatus construction company in Willich went bankrupt, Graeven took over a large share of the staff, all specialists in their fields. With these reinforcements, Graeven then entered the apparatus construction sector for the chemicals and petrochemicals industry. Over the years the company has built a good name for itself in special apparatus engineering constructions, for example for components in nickel-based alloys, titanium, zirconium and pure nickel. Graeven has 48 welding permits in pressurized equipment construction for these metals. There aren’t many companies with such a high number of permits. The alloy Invar 36, for example, has an extremely low expansion when there are temperature fluctuations. For a telescope in the Chilean desert, every thousandth millimetre counts. Graeven supplied around 1,000 individual components made of Invar 36 for 25 telescopes. Jochem Graeven was just recently in Chile himself. “At home” in Tönisvorst, his daughter Sandra as commercial director and Michael Düren as operations manager make sure everything runs smoothly.

Today the small workforce at Graeven represents a highly specialised team for calculating, constructing and manufacturing complicated apparatus. As you can imagine, alloys that have to be acid and heat-resistant are not exactly easy to weld. Even a robot in test operations didn’t perform the welding seams as perfectly as the experienced Graeven metal technicians. Graeven Metalltechnik also supplied specialist products and prototypes in titanium as well as vacuum chambers for the particle accelerator DESY in Hamburg and the largest x-ray laser in the Helmholtz Centre in Dresden-Rossendorf. Reliable and committed suppliers here are recommended to others, for example for marine engineering at EADS. Special know-how is required for welding stainless steel gas cylinders for high purity gases. But the mounting brackets for formula 1 seatbelts were also made in Tönisvorst. “We call them bottle openers because of the shape.” But as international as Graeven’s operations are, the man born in Krefeld is deeply rooted to the Niederrhein. All the staff come from the area too. Moving is unthinkable. “There are no welders from school.” Each man has become a specialist over the years. “The boys make welding seams look like they were painted on.” You can tell that Jochem Graeven is proud of his team.


Graeven Metall-Technik GmbH
Tackweg 45
47918 Tönisvorst

Tel.: 02151 701456
Fax: 02151 701325



As at: March 2013