[labnetwork] Bending coaxial

[Weaver, John R]

Matthieu –
While I am in complete agreement with most of Craig’s points, the main issue in too small a radius bend in your tubing is cleanliness rather than purity (particle count rather than “how many 9s”). If you are using a corrosive gas, purity can be affected but even more serious is the possibility of moisture entrainment that can cause catastrophic failure.
As all the responses have said, use a large-radius tube bender and you’ll be fine.
John


John R. Weaver
Strategic Facilities Officer
Birck Nanotechnology Center
1205 West State Street
West Lafayette IN 47907
(765) 494-5494
jrweaver at purdue.edu<mailto:jrweaver at purdue.edu>
nano.purdue.edu



From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Craig Cheney
Sent: Wednesday, December 17, 2014 10:21 AM
To: 'Matthieu Nannini, Dr.'; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Bending coaxial

Matthieu,

   We specialize in these types of systems and build them on a regular basis.  When bending tubing the first question you have to ask is, what is the purity and/or reactivity of the gas that you going to be running through the gas lines, and what is the quality of the tubing (carrier tubing) that is going to be bent.  If you are going to be using electro-polished tubing for the carrier tubing which I assume you are, given the two gases listed.  Then you have to take into consideration what happens when  you bend electro-polished tubing.  Even with a low radius tube bender you will create defects in the electro-polish that can lead to problems down the road.  It has been shown that even with a low radius tubing bender that you will induce micro defects into the plating on the interior of tubing that can create nucleation points that can lead to bigger problems down the road such as, particles, corrosion, and gas contamination.

    If you are starting out with a gas that is not very pure (99.9%) then you can probably live with some of the problems that will develop over time.  But given the nature of the two gases listed you have to take into consideration the reactivity of those two gases.  Given the nature of the two gases being highly corrosive that will cause the gas line to deteriorate over time, and cause bigger problems.  We would highly suggest that you use high quality electro-polished tubing as well as high quality pre-manufactured electro-polished coaxial weld fittings with welded sleeves (which is code in the U.S. for those two gases) and not mechanical sleeves.

   I hope that helps and let me know if you have any further questions.

Thank you,

Craig Cheney
[Description: cid:image001.jpg at 01C7E19F.47FFBAE0]


Desk:  (608)834-4200
Fax:     (608)834-4299
Cell:    (608)438-8714

This e-mail transmission and any attachments to it are intended solely for the use of the individual or entity to whom it is addressed and may contain confidential and privileged information. If you are not the intended recipient, your use, forwarding, printing, storing, disseminating, distribution, or copying of this communication is prohibited. If you received this communication in error, please notify the sender immediately by replying to this message and delete it from your computer.

From: labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu> [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Matthieu Nannini, Dr.
Sent: Tuesday, December 16, 2014 10:33 PM
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: [labnetwork] Bending coaxial

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

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20141217/dd16cfd7/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 5517 bytes
Desc: image001.jpg
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20141217/dd16cfd7/attachment.jpg>