Applies To
Product(s):	AutoPIPE Vessel
Version(s):	ALL
Area:
Date Logged & Current Version	March 2018 40.06.00.07

Problem:

The following Error message appears when running the program:

No. 593 Saddle effective angle < 30Deg (blast int Max P (Corroded inertias) (Corroded Weight), revise design of vessel.

How to avoid?

Solution:

Let's understand why we get the following 2 errors:

Suggest to watch webinar:

"Consider motion, seismic, and wind loadings with ease for optimized pressure vessel supports design"

The webinar will help in understanding an exactly similar case considered with motion loading.

Angle reduction is used to account for transverse loads with Zick's method.
This effective angle comes from the TEMA 8th RGP rules and/or Dennis Moss' book.

This effective angle calculation cannot be disabled.

As Sudip said the blast condition is the worst for this angle, a small effective angle can mean that the transverse horizontal loads are very large and not balanced by the weight of the vessel. In this case, another mode of support should be considered to deal with the blast condition in order to preserve the integrity of the vessel body at the supports (i.e. a square saddle).

Also, mentioned in reference help '?'

Example:

Let's consider what happens to the saddle 2 design. In this case the horizontal transverse reaction is 0:

Hence the effective angle is same as actual saddle angle (107.84 deg >30 deg) and the saddle design passes:

When you applied very high wind dynamic pressure for a load case (i.e blast analysis), it lead to high horizontal transverse reaction (ex. 18,428.2 daN)

Hence now the effective angle theta

theta= 107.84 - 2.arctan(Rah/Rav)

theta= 107.84-2.arctan(18,428.2/1,714.1)

theta= 107.84-2.arctan(10.7509) < 0

Note: less than 0 makes no sense, so theta = 0.

Therefore, the error and the saddle design needs modification. Generally increasing number of saddles and parameter B in saddle dialog box may solve the problem. However, if the load case (ex. blast, wind), drag dynamic pressure is very high then this suggestion may not work. Another suggestion increase the number of saddles or adjusting B. You may try it and also see if the blast drag is realistic. A simplistic static blast load wind dynamic pressure calculation may be over conservative and may lead to impracticality in design.

Please verify the blast drag from reliable source. Users considering blast load usually have access to known blast drag dynamic pressures which we do not have access to.

Error Code 593 - Saddle effective angle < 30Deg (blast int Max P (Corroded inertias) (Corroded Weigh

Problem:

Solution:

See Also

Q. How to model a blast load in AutoPIPE Vessel

Error Message

Bentley AutoPIPE Vessel