Mailing List flyrotary@lancaironline.net Message #42328
From: John Downing <downing.j@sbcglobal.net>
Subject: Re: [FlyRotary] Re: adding a tubing bead
Date: Sat, 12 Apr 2008 22:08:32 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Al,  JB Weld would be my choice from experience as a mechanic in the gas compression industry.  That material is awesome.  As I recall, Tracy even used it in the intake runners in the block after removal of the valves. JohnD
----- Original Message -----
From: Al Gietzen
Sent: Saturday, April 12, 2008 10:55 AM
Subject: [FlyRotary] Re: adding a tubing bead

Subject: [FlyRotary] Re: adding a tubing bead

 

Al, you could do like Tracy did on his original, wrap a string coated with epoxy around the tube.  I hope that idea it still works, as I did mine that way.  JohnD

Yes; but what epoxy?  Most epoxies lose strength rapidly above about 150F.  What keeps the bead in place at 210F when the pressure is the highest?  You would want to use an epoxy that was good to 300F.

 

Whether it works depends on the connection configuration.  Just consider the x-sectional area of the connection, the expected pressure, and the constraints counteracting the force. Some connections don’t need a bead at all.  A short coupling hose in a straight line where things are constrained at both ends needs no bead. The pressure forces offset. A longer hose with a 90 degree bend needs a bead or the pressure will blow the hose off the connection.

 

Just some rambling thoughts  . . 

 

Al

 

 

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