[labnetwork] Bending coaxial

[John Shott]

Matt:

While our facility is older than most, we have lots of bent SS coaxial 
lines.  We have a total of about 12 coaxial lines going from our bunkers 
into our clean room.  My guess is that we have on the order of 100 
coaxial 90 degree bends before our lines enter the building, another 100 
as they are routed under our subfab, and probably another 25-50 once 
they are in the clean room.  In the great majority of cases, these were 
bent on a 1 1/2" radius mandel ... even though I suspect that new 
facilities will have used a larger radius bender.  Note: while we have a 
handful of welded tees, I don't believe that we have a single welded 
coaxial elbow.

A simple test would be to bend a piece of 1/4" tubing (well, possibly 
the 6 mm ...) in a tubing bender with a 1/2" mandrel (or metric 
equivalent).  I presume that you are worried about kinking, but I 
believe that you'll find that the 1/2" mandrel works fine on the smaller 
diameter tubing and that when you are bending coaxial tubing, the inner 
wall of the larger diameter tubing (which is typically 0.0.98" (over 2 
mm) smaller than the 1/2" mandrel) serves as the mandrel for the inner 
tubing.

At least that is our experience.  Good luck,

John

On 12/16/2014 8:33 PM, Matthieu Nannini, Dr. wrote:
> Dear colleagues,
>
> A local company is proposing to bend coaxial SS tubing to install a 
> double containment gas line thus removing the need for welded 90° 
> elbows. did you ever see that ? Any comment would be helpful !
>
> Thanks
>
> Matthieu Nannini
>
> Début du message réexpédié :
>
>> *De: *"Matthieu Nannini, Dr." <matthieu.nannini at mcgill.ca 
>> <mailto:matthieu.nannini at mcgill.ca>>
>> *Objet: **Bending coaxial*
>> *Date: *15 décembre 2014 15:31:10 UTC−5
>> *À: *Tom Britton <tbritton at criticalsystemsinc.com 
>> <mailto:tbritton at criticalsystemsinc.com>>
>>
>> Hi tom,
>>
>> A local company here can bend coaxial tubing. They quoted me 4800$ 
>> for the 2 lines BCl3 and SiCl4.
>>
>> What do you think of bending ? They told me the 1/4 wasn’t kinked at all.
>>
>> Matthieu
>>
>
>
>
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