Pressure drop diff between 90 deg Elbow and Bent pipe
Pressure drop diff between 90 deg Elbow and Bent pipe
(OP)
Where can you find values to determine the pressure drop difference between a 90 Degree butt-weld elbow fitting and bending the pipe into a 90 degree elbow? Lets say the pipe is 6" Sch 40 Carbon Steel(not that it matters). The fitting is a 1.5xradius elbow and we would bend the pipe on a 6xradius bend. My crane book gives K values for the elbow but not for a bent pipe? Would there be any difference than saying the bent pipe was equivalent to a 6xradius elbow?
Regards
StoneCol.
Regards
StoneCol.





RE: Pressure drop diff between 90 deg Elbow and Bent pipe
Don't know of any data pertaining to such though.
Engineering is the practice of the art of science - Steve
RE: Pressure drop diff between 90 deg Elbow and Bent pipe
For r/d = 6 then K = 17 fT
For r/d = 8 then K = 24 fT
For r/d = 10 then K= 30 fT
For 6 in std pipe fT = 0.015
r/d = 36/6 =6
6 = 17 fT
hence
Resistance Coefficient 90 deg bend
K = 17 x 0.015 = 0.255
Crane also defines formula for bends other than 90 deg
RE: Pressure drop diff between 90 deg Elbow and Bent pipe
It also depends on how accurate you want to be. To put it in some sort of perspective, these are some K-values for water flowing at 2.5 m/s in a 100 mm pipe
6d fabricated bend : K = 0.29
90 degree mitre bend, single weld : K = 1.0
90 degree mitre bend, two welds : K = 0.50
90 degree mitre bend, three welds : K = 0.40
If your fabricated bend is not a large part of the overall resistance you do not need to be too accurate.
A useful comparison of the effect of bend radius on resistance has been done by Dennis Kirk, who often posts here and hopefully will have some advice for you. See Dennis' graph at
http:
Harvey
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure drop diff between 90 deg Elbow and Bent pipe
See
http://www
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure drop diff between 90 deg Elbow and Bent pipe
RE: Pressure drop diff between 90 deg Elbow and Bent pipe
http://kirkmansoftware.com/