Project Description

Tensioning DYWIDAG bars

FPT system for tensioning DYWIDAG bars
tensioning dywidag bar






Tensioning DYWIDAG bars

FPT is a specialized manufacturer of equipment and systems for the tensioning of the DYWIDAG bars mainly used in the systems of Post-Tensioning and Geotechnical.
For tensioning DYWIDAG bars we specifically designed a suitable tool consisting of hydraulic hollow jack single or double acting equipped with specific reaction bell and polygonal wrench and operated by an hand pump or an electrical pump unit with a working pressure of 700 bar.

The operator can hydraulically actuate the cylinder by setting the pressure required to confer the proper preload to the bar. The plus of the FPT kit for tensioning DYWIDAG bar is to be fitted with a specific reaction bell and adjustable wrench that allow the operator to have full access to the hex nut and tighten it through the appropriate tommy bar without the need for other equipment.

The system is modular and can be adapted to all types of bars from the bar of 18 to the bar of 75 . Cylinders can be manufactured in simple or double effect and are designed specifically for each single bar DYWIDAG.

Hydraulic cylinders and bolt tensioners, produced by FPT – Fluid Power Technology are suitable for tensionong high resistance bars specifically designed for civil applications. Tensioning of Dywidag and Mcalloy bar. The thread, made during the rolling process, does not affect the entire circumference of the bar, but only two diametrically opposite sectors as can be clearly seen from the drawing shown below. A limit of the thread is the need to tension the bars, putting them in tension and then tightening the anchor nuts.
It is also possible to stretch with the use of torque wrenches (manual or hydraulic) but the losses due to system frictions (friction between the thread of the bar and that of the nut) and the high stress of torsions that act on the bar (part of the applied torque due to the mutual frictions between the bar and the nut it is transferred as a torsion to the bar instead of as traction on it) they are not recommended for use when it is desired to obtain tightening values in line with the normal technical requirements (whether they be geotechnical or structural).