In early February 2002, 100 ExpaTen Bolts were delivered to the largest Italian shipyard FINCANTIERI. They are being used to connect the sections of the two shaft lines of the
French ferry "Méditerrrannée".
ExpaTen Bolts are used simultaneously to transmit the torque, free of backlash, and to press the flanges firmly together. The result is a connection of the abutting shaft flanges that is resistant against torque and bending and that can easily be disassembled at any time, even after prolonged periods of use.
The special feature here is:
Form and frictional connection are achieved simultaneously. This results in:
- Maximum torque is transmitted in the smallest space through frictional locking and, and this is new !, additionally also through 100% positive locking;
- Fastest assembly in conventionally produced bores;
- Simplest handling of the ExpaTen Bolts and the associated SCHAAF high pressure tool;
- Subsequent disassembly is just as simple and possible at any time.
The central tie bolt of an ExpaTen Bolt is designed with a tapered zone, that is surrounded by a conical sleeve (with matching inner taper). The outer diameter of the conical sleeve is slightly smaller in size than the associated bore.
The ExpaTen Bolt is simply inserted in the flange bore. A SCHAAF Bolt Tensioner is engaged and the tapered bolt is drawn into the conical sleeve. This makes the conical sleeve expand and forms an interference fit with the bore. Not only is the bore completely filled with metal, but any possible backlash is prevented between the two ends of the shafts, even when torque, speed or the direction of rotation is changing.
A high axial clamping force is then produced within the tapered bolt, so that the flanges are firmly pressed against each other. Due to the frictional locking, additional torque is transmitted.
The SCHAAF Bolt Tensioner, in this case, is designed for pressures up to 3000 bar. This makes the tool extremely small and light. The tensioning system can be used quickly and without any effort. This is especially important when working in restricted spaces, like below deck.
It was within a few hours that all the 10 shaft flanges were clamped with 100 ExpaTen Bolts that SCHAAF had supplied. There were no problems for the installation staff.
In the event of a shaft inspection, the ExpaTen Bolts can be just as easily and quickly removed: the axial pre-tension is initially released, by using the SCHAAF Bolt Tensioner. A high pressure hose is then connected to the end of the ExpaTen Bolt and hydraulic oil is pressed into the tapered seat between the tapered bolt and the conical sleeve. The components are now loose and can be easily removed.
Progress through SCHAAF high pressure hydraulic technique
The shaft flanges can be made considerably smaller in size, thus reducing the rotating mass and creating more usable space.
Precision quality bores are no longer required. The tedious and sudorific forcing of locating pins under limited operating conditions is eliminated. This lessens the risk of accidents, shortens the assembly time considerably and reduces the costs.
Approval by BUREAU VERITAS
It goes without saying that products to be fitted in a ship must be approved and accepted by a classification society.
Pertinent certificates are available.