Expa = Expansion = 100% positive locking in the flange bore
Ten = Tension = frictional connection for the joint

SCHAAF is leading the way with ExpaTen bolts in order to revolutionize detachable flange connections of propulsion shafts of the shipbuilding industry. Not only are the bolts 100% non-positive and form fitting, which transfers high torque, but even after high stress they can be easily disassembled and reused. The bending and rotating resistant connection absorbed shock like changes of revolutions, torque as well as turning direction dependently. The system is made of heat treated steel, which is a safety plus during torque transfer. The safety factor in comparison to regular screws is 5. ExpaTen is easy to handle since all tools and hydraulic high-pressure pumps for assembly and disassembly are adjusted to the system. ExpaTen is certified by well-known buyers.


SCHAAF is certified in accordance with
DIN EN ISO 9001 and, in addition, fulfils
all requirements of all classification societies.


Expansion and pretensioning result in the following
advantages compared to conventional bolts:

  • 100% positive locking and frictional connection all the
    time after mounting, no slipping between the flanges
  • Simple and quick installation and removal of ExpaTen
    even after years of use – nearly unlimited times
  • Reusable after removal, again and again
    – no sparebolts required
  • Torsionally and flexurally rigid connection even with
    sudden changes in the rotational speed, the torque,
    direction of rotation or direction of load
  • No jammed or oversized bolts any longer
  • High torque transmission, completely free from backlash
  • Reduction of flange dimensions possible due to fewer
    number of bolts
  • Maximum torque and shear force transmission
    in minimum space
  • Tolerance for mounting is 0.05 to 0.2 % of the
    bore diameter
  • Simply machinering of the flange holes is sufficent
  • Additional standard bolts can be tightened with the
    same Bolt Tensioner



ExpaTen 2
Ideal flange connection for misaligned flange bores
and / or unequal bore diameters

ExpaTen QL
Quick form and force fit connections with detachable
axial tensioning system (Quick Locking)


The standard version of the SCHAAF ExpaTen comprises the following components:

  • Tapered Bolt and Conical Sleeve of high-strength
    quenched and tempered steel for maximum shear
    strength and axial load capacity
  • Two ultra-high-strength Round Nuts
  • Fine thread for maximum fatigue strength
  • Pressure connection bore and pressure distribution
    grooves on the taper for easy removal of the
    Tapered Bolt

Areas of Application

SCHAAF ExpaTen Bolts are the optimum solution wherever high forces (torques) must be transmitted and, at the same time, easy removal must be ensured. For example ship drive shafts, powerplants, crushers, steel
and non steel mills and windturbines.


Quality Assurance

All ExpaTen Bolts are checked for material quality, dimensional accuracy, correct functioning and load-resistance. During order execution, they are subject to continuous quality assurance measures and are supplied together with detailed technical documentation.



ExpaTen Bolts are, of course, supplied packaged, ready
for installation and use.

SCHAAF ExpaTen Bolts are user-friendly, reliable, and manufactured in accordance with the highest level of technical know-how. Our highly-motivated
staff would be pleased to train your personnel, in situ or at our works, in mounting and dismantling the bolts.

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