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Joint Report Graphs
http://forums.mcelroy.com/fusion/viewtopic.php?f=1&t=1504
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Author:  lsorin [ November 20th, 2012, 6:52 pm ]
Post subject:  Joint Report Graphs

Hi,

Could anyone to explain how "Possible long Open/Close time" or "Possible incorrect shift sequence" can effect the process if the pressure chart at 100 psi for 24 hours passed?

Author:  Joshua [ November 26th, 2012, 12:42 pm ]
Post subject:  Re: Joint Report Graphs

I am not certain that I understand the question but see if this helps.
Open/Close time refers to the part of the fusion process where the carriage is opened, the heater is removed, and the fusion is made. If too much time passes before the fusion is made, the molten polyethylene can begin to create a "skin". This can affect the quality of the fusion joint.
The shift sequence refers to the way we shift the hydraulic valves to drop the pressure to drag while heating the pipe. If we do it in the incorrect order it causes pressure to be trapped in the cylinders and thus exerts force during the heating cycle. Heating under pressure is a major no-no and can result in a cold fusion.

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