[labnetwork] Heat trace issues on DCS gas lines

[Mike Young]

Hi Vito. I would posture that failure might have been more likely *in between* the fastening tape locations, where the “heat sinking” of the tape is the worst, and hence the temperature of the heat tape was the highest, yeah? The spiral wrap would have left the tape in intimate contact with the tube over the tape's entire length, thereby minimizing hot spots...

—Mike


> On Jan 21, 2015, at 12:23 PM, Vito Logiudice <vito.logiudice at uwaterloo.ca> wrote:
> 
> Dear Colleagues,
> 
> We are experiencing an issue with the heat trace on our Dichlorosilane gas line. The all-welded 1/4" SS line is encapsulated with a 1/2" SS outer containment  line which is itself heat traced with a single strand of heat trace that runs the entire length of the coax assembly. The 120 foot line is insulated as shown in the attached photo. A portion of the heat-trace appears to have failed prematurely (it was installed less than one year ago) and we are wondering if the method of installation may be the cause.
> 
> The heat trace was not installed in a spiral fashion around the outer 1/2" tube. Rather it was installed in a straight fashion along its entire length with "heat trace fastening tape" located every four feet or so. A member of my team has suggested that such a straight rather than spiral installation may have caused hot spots (at the fastening locations) which may have in turn caused the failure.
> 
> I would appreciate hearing from the community on this point: Are the heat traces around your low pressure gas lines spiral-wound around the lines or are they installed in a straight fashion and somehow fastened along the entire length?
> 
> Other insights/suggestions on the proper heat tracing of gas lines by experts in the field as well as comments on possible causes of premature heat trace failure are very much welcome and appreciated. Thank you.
> 
> Regards,
> Vito
> --
> Vito Logiudice  P.Eng.
> Director of Operations, Quantum NanoFab
> University of Waterloo
> Lazaridis QNC 1207
> 200 University Avenue West
> Waterloo, ON           Canada N2L 3G1
> Tel.: (519) 888-4567  ext. 38703
> Email: vito.logiudice at uwaterloo.ca <mailto:vito.logiudice at uwaterloo.ca>
> Website: https://fab.qnc.uwaterloo.ca <https://fab.qnc.uwaterloo.ca/>
> 
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-- 
Michael P. Young                                (574) 631-3268 (office)
Nanofabrication Specialist                      (574) 631-4393 (fax)
Department of Electrical Engineering            (765) 637-6302 (cell)
University of Notre Dame                         mike.young at nd.edu
B-38 Stinson-Remick Hall
Notre Dame, IN 46556-5637

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