Dynamic forces exerted by a duct

[pch1]

I have posted this topic in the piping and fluid mechanics section, but I was hoping to locate a standard to refer to:

Can anyone help me locate a standard or similar that will guide me in determining the dynamic forces exerted by a gas flowing through a circular duct.

I do have access to most British and European standards, but only a few American standards if anyone is able to point me to a particular standard.

The conditions are:
Duct Size: DN1000
Duct Material: Carbon Steel to BS EN 10025 S275
Duct wall thickness: 8 mm
Flue gas pressure: -0.5 barg
Flue gas flow rate including water vapour: 32318 kg/h
Solids in flue gas: 1250 kg/h

The duct starts at a waste heat boiler (WHB) and feeds to an electro static precipitator (ESP). Between the WHB and ESP, the duct undergoes two directional changes of 45 degrees each in the Z plane, separated by a straight section of duct approximately 2 metres. There are expansion joints (Bellows) located at both WHB and ESP.

I did a quick calc on the forces exerted by the flue gas at one of the 45 degree mitred bends (Made of 5 sections) and have come up with 118 N in the horizontal direction and 49 N in the vertical direction.
Please note that these calculations may not be spot on as I have assumed a gas density of 0.657 kg/m^3 and a velocity of 18 m/s.
(I took a bit of help from this website:

http://www.nawabi.de/chemical/hrsg/page6_7.htm

)

Thanks in advance
Paul Hearn

 

[marcoh]

Without doing the calcs I would have thought the dynamic forces would be negligible relative to the static forces for the duct (ie due to duct weight)?

 

[pch1]

Marcoh

Yes the dynamic loads are small compared to dead and wind loads, but I was hoping to get hold of a standard so I could check my work.

What calcs would a person use for the duct in question?
I have used basic fluid mechanic calcs to determine the forces at the change of direction (i.e. Linear-momentum equation F=?Q(V2-V1)).