Unfortunately, <font color="#0000ff">
NEMA SM 23</font> is ambiguous about the point of resolution of the combined forces and moments. The resolution points have been interpreted to be the following two points:
1. The face of the flange at the exhaust nozzle connection.
2. The intersection point of the exhaust nozzle centerline and the equipment shaft centerline.
In order to resolve the forces and moments at the exhaust nozzle connection, enter the X distance from the exhaust nozzle to each connection.
In order to resolve the forces and moments at the intersection point of the exhaust nozzle and the shaft centerlines, enter the X distance from the intersection point to each connection.
I really can't advise you on which resolution point you should use, since this would be offering
engineering advice on an ambiguity in the NEMA standard. However, I do have a written (fax) statement from the NEMA board sent to one of our customers (in 1997) that states:
The forces and moments on the steam turbine connections are to be resolved about the intersection of the centerline of the turbine exhaust and the centerline of the turbine shaft.
We have been unable since this time to obtain any additional information on this particular topic from NEMA.
Whatever you decide to do, make sure the owner/operator/inspector all agree.