#40315 - 01/20/11 04:06 AM
API 650 Rotation
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Member
Registered: 07/03/08
Posts: 71
Loc: India
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Rotation of Shell of a tank calculated as per API 650 gives theta, the same is implemented in nozzle (API 650) which is reflected in Error Report .
My query is Figure P-1 of API 650 considers anticlockwise rotation as negative, however I believe Caesar (Rx entered as vector in Node XX) considers clockwise rotation as negative.
Should we convert the sign of nozzle rotation from error report while feeding as a displacement vector?
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#40316 - 01/20/11 04:23 AM
Re: API 650 Rotation
[Re: stressguy81]
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Member
Registered: 04/22/05
Posts: 1453
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It have nothing to do with clockwise or anticlockwise (only by chance). Rotation will be downward. If the nozzle is oriented like in the API figure, then the rotation is by chance anticlockwise. If it was 180 degrees rotated it would be clockwise. Sign is related to the axis orientation and nozzle orientation.
Regards,
_________________________
Dan
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#40320 - 01/20/11 06:06 AM
Re: API 650 Rotation
[Re: stressguy81]
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Member
Registered: 04/22/05
Posts: 1453
Loc: ...
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Exactly what I said.
You enter +1.21 because X axis is oriented as in your sketch.
Caesar considers clockwise rotation as +, but you should looking where the arrow is pointing.
Regards,
_________________________
Dan
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#40336 - 01/20/11 12:09 PM
Re: API 650 Rotation
[Re: danb]
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Member
Registered: 12/29/99
Posts: 197
Loc: Houston,TX,USA
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One should look at the deflected shape and/or animation in the output graphics to confirm pipe is deflecting as expected.
_________________________
Bob Zimmerman, P.E. Vice President of The Piping Stress International Association (The PSI)
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#40339 - 01/20/11 12:45 PM
Re: API 650 Rotation
[Re: Bob Zimmerman]
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Member
Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
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Danb - you said CAESAR II considers clockwise rotation as +.
This isn't necessarily true. CAESAR II uses the "right hand rule" to determine postive/negative rotation. Using your right-hand, put your thumb on the axis, pointing to the arrow head. The direction your fingers curl is positive rotation.
_________________________
Regards, Richard Ay - Consultant
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#40343 - 01/20/11 01:46 PM
Re: API 650 Rotation
[Re: Richard Ay]
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Member
Registered: 04/22/05
Posts: 1453
Loc: ...
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You are right. Actually I was saying this thinking that I'm the one that turn around and looking where the thumb is pointing (fingers curl clockwise). My english is not so good.
Best regards,
_________________________
Dan
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#40355 - 01/21/11 03:33 AM
Re: API 650 Rotation
[Re: danb]
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Member
Registered: 04/22/05
Posts: 1453
Loc: ...
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Stressguy81,
You are looking at a wrong picture. You should look at the one on the left. You will notice that the rotation is in accordance with the left figure coordinates system. If your nozzle have the same coordinate orientation you can maintain the sign, if not, you have to change.
The figure that you attached is for Rotation under a radial force.
Regards,
_________________________
Dan
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#40358 - 01/21/11 05:36 AM
Re: API 650 Rotation
[Re: stressguy81]
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Member
Registered: 04/22/05
Posts: 1453
Loc: ...
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I do understand now what you want to point out. Well, it is the stress engineer responsibility to make sure that displacements are inserted correctly. Caesar offer you a small calculator that is in accordance with API 650 figure and formula and do not automatically adjust coordinates.
With 5.3 will not be necessary to do this because from 5.3 presentation I understand that you can import the rotation so it will solve also this problem.
Regards,
_________________________
Dan
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