Flare Velocity

[TomasAron]

I was asked to design a flare stack structurally. The flare is going to be supported at two locations, at the base and about 1/2 of the way out. The flare stack is angled about 40 degrees at the end.
Now here is something that scares me. (I have designed low flow flare stacks before.) The potential velocity for this flare is just below subsonic. And I just imagine a fire fighter holding a hose and turning the valve on.
My question is does anyone know of any standards/formulas that can equate these discharge forces. (Not exactly handled in ASCE, or API RP 2A). I have the feeling like the Mechanical Engineers are not giving me all the information I need.

 

[epitome1170]

The only time I have designed a flare stack support the owner provided that information (as I understand it) because it varies based on the chemical (propellant) being burned off.

The other option if the owner (or owner's rep or operator) does not know is if you talk to the pipe designer (which may or may not be the MEP).

I doubt any SE would know or be proficient in loads in flare stacks though.

 

[JStephen]

http://www.engineeringtoolbox.com/forces-pipe-bends-d_968.html

The actual thrust wouldn't be that hard to work out, as it's similar to water flow in a pipe. See the link above.

Note that the speed of sound depends on temperature and density, and isn't necessarily the same for your gas as it is for air.

With water piping, the pressure forces usually are far in excess fo the dynamic effects. In your case, velocity is much higher, density would be much lower, and it's not immediately obvious what the scale of the force would be.

You might also inquire as to the frictional drag on the stack.

 

[TomasAron]

JStephen, that website will be helpful. I talked to the client and I guess the project fell through so I do not have to worry about it at this point. But it is good to have this for any future projects of this type.

epitome170. Thanks for the personal experience/advice.