Anchor Restraint On Flanges (Caesar II) 5

[Timeyin]

Hi everyone,
I've been going through some Caesar II model to profound solution(s) to the failing pipe.
Going through most of the existing models I noticed that an anchor type restraint was placed in-between connecting weld neck flanges. This was repetitive in all the models I checked.
Generally whenever I'm modelling with Caesar II, I only use the anchor type restraint at connection points (connections to equipment etc).
My question now is, when do we use anchor restraints?
Is it typical to place a restraint in-between two connecting flanges?

 

[pennpiper]

Timeyin,
You wrote:
"I noticed that an anchor type restraint was placed in-between connecting weld neck flanges."

I have never heard of such a thing as this.
Can you post a picture, a link or something that gives a better description?



prognosis: Lead or Lag

 

[Timeyin]

Here is a snap shots of what I mean.

 

[LittleInch]

Are you sure this is an anchor type restraint? doesn't appear to have a node number and may just be a gasket?

No, it is not normal to have any restraint between flanges. If it is an anchor it may well be why your pipe is failing....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Timeyin]

Apparently its an anchor, its clearly specified on the "classic piping input" portal.
Thanks for clarifying.

 

[BigInch]

If it stops the pipe from moving at that point, then it's an anchor. Does it move at that point?

Learn from the mistakes of others. You don't have time to make them all yourself.

 

[pennpiper]

In my opinion;
I would not use a Flanged joint as an anchor as is being portrayed by the original poster.
I would have given some thought to using a "Puddle Flange", it would serve the same purpose but without the risk of flange distortion and leakage under stress.

prognosis: Lead or Lag

 

[rconner]

If this "snapshot" is meant to be the finished part, I'm not sure that it in an of itself would be capable of any significant anchorage (unless perhaps the conical bell and slight triangular protrusions were encased in sufficiently strong and buttressed concrete, and with the thrust in the right direction). Any chance the triangular tabs are on the other hand meant to be drilled for 4 bolted anchor rods running to some other anchorage point on something??

 

[pennpiper]

This is what I was referring to.
\I hope the link works.

http://www.alibaba.com/product-detail/XW-Flange-premium-manufacturer-carbon-steel_1895987357.html

prognosis: Lead or Lag

 

[Timeyin]

Hmnnn,
Learnt alot already.
Pennpiper, that anchor flange seems to make a whole lot of sense.
Thanks

 

[C2it]

WHOA ..... I DON'T BELIEVE THIS AN ANCHOR FLANGE !!

It looks to me like a common method of modelling both flanged joints and other significant locations in Caesar II, where the user wants to quickly see forces and moments, without looking through the whole Element Listing Report.

An 'anchor' is defined at the flange face, but not connected to ground, instead connected to the adjacent element with a Cnode. The internal loads then appear in the 'Restraints Summary' like other anchors.

The Cnode is defined in the relevant Restraints input data and the next element connects numerically to it, rather than the preceding element node.

In the plot, the 'flat plate with pointy bits' visible in green is simply the Caesar II representation of an anchor, real or implied, and is dimensionally related only to the element pipe size

Confused ? You will be.

 

[Timeyin]

C2it, thanks a bunch.
I just rechecked the model and noticed that it is actually connected to the adjacent element with a "Cnode".
This just clarified my initial confusion.

 

[pennpiper]

C2it,
Your statement [highlight #CC0000]"An 'anchor' is defined at the flange face, but not connected to ground, instead connected to the adjacent element with a Cnode. The internal loads then appear in the 'Restraints Summary' like other anchors."[/highlight] suggests to me that your experience is all form behind the key board and computer screen. If you think an Anchor is just a "Cnode" on a report then you need some real world field time.


prognosis: Lead or Lag

 

[C2it]

Pennpiper .....

With all due respect ... bollocks.

I don't need to list my experience, save to say that it exceeds 35 years in every kind of project from offshore thro' refineries to nuclear, mostly but not exclusively Piping and stress based.

Of course I spend time in office based analysis. I have used Caesar II since 1987.

With regard to Cnodes, it's just Coade terminology and quite a useful feature of the software. I know very well the limitations of an 'anchor' - real or implied, and I would never specify one - that is, a point fully fixed against all translations and all rotations, unless I were sure that the 'real world' was able to accommodate it. My comment was specifically addressed to and 'implied' anchor at a flange face ... it's just away of getting the data out and has no effect on a stress calc.

Incidentally, I am a UK chartered engineer and a Fellow of the Institution of Mechanical Enginers.

Pennpiper ... What is your background that enables you to make such unjustified, rude and ignorant remarks ?

 

[Timeyin]

Sirs,
Please lets avoid these kinda discussions.
The fact remains that there was a question, and it has been successfully answered by you guys.
Thanks for your inputs guys; they have been really helpful.

 

[BigInch]

IMO, seemingly knowing both of you guys pretty well by now, I'd say that you are both equally well qualified to have your own equally valid opinions. It's got to be a simple misunderstanding. Let's not worry any more about it.

Learn from the mistakes of others. You don't have time to make them all yourself.

 

[saplanti]

C2it is correct. When the piping modeled in sections in different files, CNODEs are used to connect these sections in one model. In the model these look like anchors, and you can get the loading at those locations. Some analysts use these type modeling to be able to get the loading in the list for support loading for their investigation on flanges which is unnecessary today since CAESAR II was improved a lot and you can get flange loading without using this type modeling method any more.

 

[MJCronin]

Weld neck anchor flanges are offered and (apparently) are in use in subsea and pipeline applications.

http://www.wfi-intl.com/index.php?page=anchor-flanges

More info here:

http://www.namdaran.ir/Site/EN/Anchor Flange.html

MJCronin
Sr. Process Engineer

 

[BigInch]

Yes they are. Since many, many years now.

you must get smarter than the software you're using.

 

[saplanti]

It was mentioned that the same type anchor is available at the flange connections to the equipment in Timeyin's first post. I have not seen any anchor flange used at the equipment connections. So this tells me that the CAESAR II model does not intend to use an anchor flange.

In fact this easily can be answered by looking at the piping isometric drawings. I trust Timeyin can provide thus information or images at the flange connections mentioned.