Hi all,

I have a problem with my can. My pipe is lifting and my hot load are getting bigger...... How is it posible?

Regards!

ya but bigger means what.....

sorry i mean bigger than my cold load..

Thanks for the correction shukla..

Regards!

move the support location & try .

Hi BOM,
I think looking at the pipe route, place where CAN is attached and during expansion if its under compression or tension will give better idea about result.

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Naren

Hi neveenleo and naren,

Thanks for your reply.

The result would realy vary from the principle of spring form my result. I was reffering to lifting-off of the line supported with spring can. I am expecting less hot loads than my cold load. Example I have a spring can with 26.8kg/mm with cold load of 2000kg, and when it operate it lifted off(PUMP SUCTION SEGMENT) my loads are now 2010kg. WHY????

Regards!

If the figures quoted in example are correct, for a lift of (2010-2000)/26.8 = 0.373 mm, you are using a spring. See if you can move the can away from source of lift, you might get to a point where no spring is needed. Do perform a check on loads at nearby sensitive points (nozzle for example) alongwith it.

For the sake of discussion, hot load can be greater than cold load when a spring is designed with cold balance approach.

Hi Bom,
is it possible for you to share the CAESAR II file with us.

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Naren

Hot load can be greater than a cold load if in the system undergo sagging during operation. but since this system as I examine the node undergo lift-off, there's no such way that this will produce bigger restrain load, as it is a can.

I suspect that there is an irregularity of modelling the last caesar guide in modelling can with friction.. both node intersection of the header and to the point where can is connected, must have same displacement as that segment declared as a rigid.

Naren sorry I cant. you can reffer my query to the manual on can with friction.

Regards!

Dear Bom

Please check the support arrangement in your calculation system.I had on experience that if the system is unbalanced, you will have such a issue.
I mean that reveiw your pipe supports on the otherside of the spring, if it is un supported for a portion of(unbalanced), due to that there will be extra load on the spring (beccause unbalance).This can be rectified by placing additional support on the otherside. By doing this you will get the correct sustain load on the point and after that you will get correct operating load.

In brief, the sustain load which you are getting in the spring is not a correct load.There is an additional load due to the system is unbalanced.

I hope that my presumption is correct.YOu just check and give me your feedback

regards

Sha.

Hello bom,

I understand that the result of your calculation is completely the opposite to what is expected.

For us to clearly understand what is going on in your calculation, it would be helpful if you could share the file to everyone, for study purposes.


Best regards,

Hi,
Your problem seems unique.
One possibility may be the rigid support near the spring not working or taking very little load in operating condition.

Regards
Siv

Hi everyone,

Thank you for reply..

I realy take my time to bring this file back. The problem is now different I can see that the rigid component just expanded please see node 115 and 1010. My observation is node#115 experience lift-off of .4mm and node#1010 sag with -.2 mm and they are both in the same segment modelled as rigid.

Regards!

Bom,

Your attachement is not opening.....


regards

Sha

Two sugegstions:

1) Either get your analysis reviewed by an experienced engineer in your organization.

2) Send the file to either coade or any member in the forum.

Regards

Thanks anindya, I will send this query to Sir Richard Ay.

Regards!

bom,

If you are looking at the Spring Table or you manually input the spring, the Cold Load you are looking at is theoretical.

Review the spring displacement and load in your sustained case and compare that to your operating displacement and load.

Good luck,

Thanks NozzleTwister,

I was not able to send the file for I have no authority of email. sorry..
I hope I can post the model here.

Re-examining the model error now the concern is not going for spring(spring is okay).. but for rigid element which expand???????.....

Regards!