Furnace tube pinch

[MechEMain]

Does anyone know how to decide at what pressure the pinching should stop so that the tube is not over pinched or not pinched enough?

Thanks,

 

[deanc]

Assume you mean tube expansion.

http://www.mgt-inc.com/tips/Technical_Tips_Vol_1_3.html

Start here

 

[unclesyd]

Are you referring to pinching off a tube like a pig tail on a furnace or a steam line?

 

[MechEMain]

unclesyd,
Yes, it is pinching off a tube at the pigtail on the furnance.

 

[unclesyd]

We use an older Biach Crimper and there is a red line on the pressure gauge to indicate the stopping point. That said I've seen this pressure exceeded numerous times especially on drip legs on 650# steam systems.

As far as I know we have never had any problem crimping pigtails on our hydrogen plant using the recommend max pressure. If I remember correctly the dies that we used are designed so there is limit on travel that makes cutting a tube a very remote possibility. The moving die is also very rounded to minimize any shearing.

I don't know if I can get someone to open the tool chest and get a number for you, but I will try.

 

[MechEMain]

Thanks, unclesyd.

This pressure should be different with different side of pigtails and also varies with materials. I wonder if there is any way to calulate based the size and the material of the pigtails.