Problem:

Snow load cause "NAN" in AutoPIPE's output report, 

Why and how to fix it?

Answer:

AutoPIPE is unable to apply a snow load to a pipe with Near zero length element. Typically this types of issues occur where where fitting bound components are modeled (i.e. Flanged-elbow, back to back elbows, elbow - reducer, etc..)

The problem in the model is created by run points of certain length inserted after bends. 

Example: the bend at B08 has a Near and Far points. The Bend's far point,  B08 F, is located at:  

The next node point, B09, is model some distance from the Bends TIP at B08:

Notice that the location of both B08 F and B09 are at the exact same point. AutoPIPE will issue a warning in the model consistency check report; W726-6: Near zero length element at point XXX

Workaround:

Option #1:

If B09 is not necessary to the model analysis, Delete it from the model.

Option #2:  

if B09 is necessary to the model analysis, consider using the Move/Stretch command to add a little more distance between B08 and B09 as to not cause B09 to have the same exact coordinates as the bend's Far point B08 F.

Option #3:

Decrease the size of the Bend's radius by a small amount. Thus reducing the distance from bend node point (B08) to the respective Near (B08 N) and Far (B08 F) Points.

AutoPIPE 9.6.2.x and higher will be updated to allow near Zero length pipe with snow load. However, it is still preferred practice to have no 2 node points in AutoPIPE that have the exact same locations. 

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

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