Turbine Generator Coupling, Radial Expansion Bolts

inserting bolt
Easy insertion of split sleeve and tapered stud shown.

Small 3/8" torque wrenches for low, 74 ft-lb set screw torque. Original 3-1/8" diameter bolts required tightening to 12,563 ft-lbs with a hydraulic wrench.

Old Method: High speed turbine couplings often utilize fitted bolts which can be difficult to install and remove. Often, hydraulic jacks are required to remove the fitted bolts and sometimes they need to be drilled out. Stud drilling can take as much as a full shift per stud. This can increase the unit outage time if the turbine work falls within the critical path of the outage.

Solution: Superbolt Radial Expansion Bolts transmit a large radial force to the coupling hole but are inserted and removed with the ease of a loose fitting through-bolt. Installation or removal of the full set of bolts can be achieved in only a few hours with a small, 3/8" drive torque wrench. Perfect alignment of the holes is achieved every time.

Comparison to hydraulic radial fit bolts: Hydraulic bolts are more complicated and much more expensive than the Superbolt system. Hydraulic bolts require components such as a hydraulic pump, hydraulic tensioners, and various adapters. Additionally, the hydraulic systems require expensive hydraulic alignment tools in order to insert the tight fitting solid sleeves. The Superbolt split sleeve design permits a much looser fit in the coupling bolt hole for easy installation and removal without an alignment tool. The Superbolt system also requires fewer machining steps for preparation or modification of the couplings and spacers.