SCHAAF - NEWS October 2005

Ring-type pretensioning device for COGNIS delivered (and installed) in record time

The COGNIS Group, a global supplier of innovative products in the specialty chemicals sector, whose major customers include the detergents and cleaning products industry, the nutrition and health industry, as well as a number of other branches of industry, such as paints and coatings, awarded SCHAAF GmbH & Co. KG the order to construct a ring-type pretensioning device for the cover of a hydrogenation reactor for the COGNIS Malaysia production facility. In spite of the short time span between award of the order and delivery/installation and other adverse circumstance, SCHAAF was able to execute the order within the agreed time limit.

The COGNIS order awarded to SCHAAF GmbH & Co. KG involved fastening a reactor cover, with a diameter of more than 2 metres, by means of twenty 5 inch (127 mm) bolts using a ring-type pre-tensioning device.
The ring-type pre-tensioning device comprises 20 bolt tensioners with drilled holes, which are mounted on a supporting ring (blue, see photo). These are connected with each other by means of a closed circular line. This device obviates the necessity of gradually tightening individual bolts crosswise in several steps, as all bolts have the same pretension force during the tightening process. The screwed connections can be disconnected just as easily in a single step.

Details per Klick

The SCHAAF ring-type pretensioning device allows simultaneous and completely uniform pretensioning of all 20 bolts in a single operation and, thus, ideally fulfils the special requirements of the operator. As a result, it is ensured that the cover fits firmly and tightly against the reactor housing. Apart from saving an enormous amount of time, the method offered by SCHAAF protects the flanged and sealing elements to a particularly high degree.
The tensioning cylinders operate with a maximum hydraulic pressure of 1600 bar and are equipped with an extremely fast automatic piston return and an internal fixed limit stop in accordance with the latest state of the art. Consequently, simple handling, coupled with absolute work safety, is ensured.

Details per Klick
A similar device was delivered to Malaysia by SCHAAF in 1991 and has been in continuous use since then without any problems being experienced and trouble-free. COGNIS logically again insisted upon delivery of a SCHAAF ring-type pretensioning device, even though the overall contract for the erection of the production facility had been awarded to another German company. COGNIS purchased a complete package from SCHAAF , comprising all the components necessary to perform pretensioning such as the pretensioning device, high-pressure hoses, distributors, pumps, centering mandrels, replacement parts, etc., including the toolboxes needed for these.

In addition, due to the overall height of the reactor, during the acceptance test, the pretensioning device had first to be installed vertically instead of horizontally. In spite of this handicap, two fitters were able to perform a complete clamping/releasing operation in less than one hour. At the same time, the skilled Malaysian personnel who were present were familiarized with handling the new “tool” by the SCHAAF representatives.

Details per Klick

Products and methods of the category described here are, once again, impressive evidence of SCHAAF GmbH & Co. KG’s innovative strength. All customers – including, of course, those who only have “small“ connection problems to be solved – benefit from the advanced technology and efficiency demonstrated by SCHAAF GmbH & Co. KG.