Volumes up to 1000 m3

Thanks to the Bolt-Tec silo’s special connection and assembly technique, the costs related to long distance transport – which make up a large part of the overall expense – can today be significantly reduced. Bolt-Tec silos can cut the logistics costs for road transport by up to 30 %. One big advantage is that the costs for transport and assembly can be accurately calculated because containers are used for transport rather than wide-load trucks. The freight costs for a 40 ft container are far lower than the costs for normal transport – particularly if sea freight is chosen, which is now up to 80 % cheaper. This is especially beneficial in regions with underdeveloped infrastructure, where conventional silos can only be forwarded using expensive wide-load transport. Damage to silos in transit is now also a thing of the past.

This system has several other points in its favour: the silos grow with the requirements. Each silo can be enlarged quickly and easily should more storage space be needed in the future. Disassembling a silo and reassembling it at another location can also be carried out without difficulty. Unlike the segmented structure of traditionally assembled silos, where the mechanical connections were achieved by means of screws, rivets or subsequently welded joints and the sealing with rubber or plastic soft seals or a seal weld, bolted silos resort to a special connection technique consisting of a T-joint and a special internal gasket that seals the silo optimally without any additional welding.

This connection concept played an important role when Bolt-Tec silos were awarded a TÜV certificate and took the pressure endurance test. They can now be used in many different applications. This established design is meanwhile employed for silos with a maximum volume of 1000 m3 in response to the ever increasing demand among plastics producers for higher capacities.

In order to meet this demand, the Zeppelin Group invested about three million euros at its Friedrichshafen site. A new assembly line was built to enable more efficient and better automated production of modular silos in segments. The automatic production line comprises welding robots, a decoiler, a milling machine and a specially developed welding unit that ensures the highest possible quality. The decoiler, which can process aluminium coils weighing up to 10 t, is a special feature here. Thanks to this automated process, compliance with even the smallest tolerance classes can be assured. This is also reflected in the silo’s stability: the more closely the silo geometry matches that of an ideal cylinder, the less danger there is of silo shell buckling. The flange connections have also been designed for maximum load on the basis of FEM calculations. Once again, maximum safety with optimised material utilisation prevails.

One major advantage of the modular design is that the delivery times are significantly shorter. The time to get a Bolt-Tec silo to the customer is nowadays only half as long as for a standard welded model, because not only the silo type but also all segments have been standardised, thereby reducing the execution and manufacturing times. Moreover, Zeppelin can produce the silo segments fully automatically for stock. When an order is received and the static requirements have been taken into account, the segments simply have to be picked and shipped.

Since the Bolt-Tec silos went into series production, far more than a hundred of them with a total volume of approximately 30,000 m3 have been expedited all over the world in the past 24 months. Modular silo construction will help the image of inflexible silos to vanish for good. This innovative system makes child’s play of relocation, subsequent enlargement and even retrofits to adjust to other bulk material.

Hall 4, Booth 305

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