pipingdesign: Re: Trunnion on an Elbow

From: <mechengr1977>
Date: Thu Nov 21 2002 - 07:35:00 EST

general practice is simply to weld a piece of pipe with slightly smaller diameter than the elbow and leave the other end open. the limiting condition will be the lenght of the trunnion and the diameter of the elbow. a chart would normally suffice. the use of FEA in this type of problem is an overkill for pipe that follows industry accepted routing.

In PipingDesign@y..., Geoff Stone DD&D Australia <blenrayaust@y...> wrote:
> Tushar,
>
> It depends upon the the detail of the trunnion mount. If the
mounting bracket
> is small in respect of the elbow I dont see why you cant take this
approach.
> After all the pipe support industry shows this type of support. If
you are
> right on the limit of stress at the elbow you may want to use FEA
to look at
> the stresses.
>
> Geoff
> --- zope_tushar@f... wrote:
>
> <HR>
> <html><body>
>
>
> <tt>
> Geoff Stone, 
> 
> Do u mean that elbow with trunion and without trunion will show
same 
> behaviour in the thermal case?? I mean will they absorb the same
 
> displacement?? 
> 
> Tushar 
> 
> 
> 
> 
> PipingDesign@y... AT SMTP 
> Sent by: Geoff Stone DD&D Australia blenrayaust@y... AT
> SMTP 
> 11/15/02 01:00 PM 
> 
> 
>        
To:    
> PipingDesign@y... AT SMTP@ccMTA-sgsinmx001 
>        
cc:     (bcc:
> Zope Tushar/fwsg) 
>        
> Subject:        Re:
[PipingDesign] Re:
> Trunnion on an Elbow 
> 
> 
> 
> 
> The trunnion detail that you are referring to is usually a thin 
> plate welded to 
> the back of the elbow over a relatively small section of the
outside 
> radius. 
> 
> Thinking about it, when the elbow is strained in plane or out 
> of plane the SIF 
> wouldnt be changed drammatically. In-plane the elbow will be 
> changed from 
> circular to elliptical and out of plane the elbow will rotate 
> because the 
> trunnion plate is relatively thin and will deflect. Any comments?
 
> --- mechengr1977 mechengr1977@y... wrote: 
> 
> <HR> 
> <html><body> 
> 
> 
> <tt> 
> the use of trunnion welded to the elbow is a common practice in 
> 
> refinery, power plant and petrochem. Charts has been develop by 
> 
> engineering/contruction firms such as Flour Daniel and Bechtel 
> to 
> aid in its sizing/selection. This SIF business is getting out 
> of 
> hands. 
> 
> --- In PipingDesign@y..., &quot;KAUSTUBH JOSHI&quot; 
> &lt;kvj@e...&gt; 
> wrote: 
> &gt; Dear Shreedhar, 
> &gt; 
> &gt; When a trunnion is welded onto the bend, the bend
looses 
> the 
> flexibility. So in actual case, the flexibility factor 
> associated 
> with the bend will reduce. 
> &gt; 
> &gt; You should try to put supports away from bend to use
the 
> 
> flexibility of the bend. 
> &gt; 
> &gt; Regards, 
> &gt; Kaustubh 
> 
> </tt> 
> 
> 
> 
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Received on Thu Nov 21 07:35:00 2002

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