A major reciprocating and screw compressor OEM required a series of special couplings. This OEM designs packages for natural gas downstream, midstream, and upstream processing. A gas field in Australia needed the couplings for large, motor-driven screw compressors (2,675 kW @ 1,493 RPM) being built.

The compressor project’s 3rd party torsional analyst contacted Altra Couplings to inquire about the potential development of a modified Torsiflex disc coupling with reduced stiffness. The compressors also utilized a keyless shaft and the customer did not want to heat shrink a hub onto the shaft that could not be removed.

To meet the application duty requirements, Altra Couplings engineers reconfigured the Torsiflex coupling spacers (utilizing heat-treated alloy steel) to reduce stiffness so the system would not operate at or near torsional resonance. Altra also incorporated a Torsi Lock hub on the compressor side of the couplings, which can be easily installed and removed for routine compressor seal maintenance. Torsi-Lock hubs eliminate fretting of the hub to shaft while combining the ease of a slip fit with the power of a shrink fit. The coupling’s drop out center section also aids in fast disassembly.

Based on Altra Couplings willingness and ability to provide a customized coupling solution, the modified Torsiflex couplings were specified and ultimately ordered by the customer.

The Model TFI2500 couplings supplied had a torque rating of 221,275 in.lb. All Torsiflex couplings feature a robust disc pack design which allows for greater torque load in a smaller coupling, resulting in lower weight. Large bolts are utilized for high clamp load, increased frictional torque load, and reduced bolt bending stress.

Highlights

• Robust disc pack design for greater torque load in a smaller coupling, resulting in lower weight
•  221,275 in.lb. torque rating
•  Custom-configured spacers (utilizing heat-treated alloy steel) to reduce stiffness
• Torsi-Lock shaft locking hubs incorporated on the compressor side of couplings provide easy installation and removal for compressor seal maintenance