6　Coupling Design

6.1　The purchaser shall specify the following requirements as a minimum,where applicable:

a)Type of train;

b)Rated power;

c)Rated speed and variations;

d)Maximum continuous speed;

e)Any defined overspeed;

f)Angular misalignment;

g)Axial displacement and thermal expansion;

h)Shaft-ends sizes and styles;

i)Distance between shaft-ends;

j)Operating temperature;

k)Type of driver;

l)Driver performance parameters(driver service factor etc.);

m)Expected transient(peak)and cyclic torque conditions.

6.2　The purchaser shall specify the maximum angular misalignments the coupling is expected to experience during startup,normal operation and shutdown of the coupled machines,normally expressed as parallel(or lateral)offset and/or angular misalignment between the coupled shafts.Unless otherwise specified,the steady-state angular misalignment capability across each flexible element shall be not less than 0.2°.

6.3　The purchaser shall specify the maximum axial displacements the coupling is expected to experience,expressed as the amount and direction of the relative movement of the shaft ends toward or away from each other as the coupled machines go through their startup,normal operation and shut-down cycle.Unless otherwise specified,the minimum steady-state axial deflection capability shall be determined by the largest shaft diameter divided by 125.

6.4　Unless otherwise specified,the steady state torque of the coupling shall be based on the torque required by the driven machine at the rated operating point.

6.5　For steady-state conditions,the coupling shall be sized based on the drive rating multiplied by 1.2.

6.6　The coupling shall be capable of transmitting a specified transient torque associated with a generator short circle and/or a motor breaker re-closure without damage.

6.7　The coupling design shall be in accordance with Sections 6.5-6.8,6.10-6.11,6.13-6.15 of ISO 10441-2007.