Dear Friends,

I had a query regarding Design of Rod hangers supporting piping in vertical direction.

If at Rod hanger support location Dead weight load = 78000 N while in Operating condition load = 48000 N.

1) Stresses in Expansion case are within Allowable values (90% without using Liberal)

2) Load difference between Operating and Sustained suggest that compressive load acting at support location = 30000 N. However, since the deadweight load is very high the net load at the support location is Tensile i.e equal to 48000 N.

I checked the Allowable load carrying capacity of the Hanger rod (M60) in compression and found the value to be around 3800 N which is not comparable with the compressive force developed as the pipe shifts from Cold to Hot conditions (i.e. Expansion case).

I would like to have the opinion of the users whether the Rigid hanger will have any possibility to buckle due to the Compressive force developed as Pipe shifts from Cold to Hot condition even though the Net load at support location is Tensile.

Looking forward to your comments

Best Regards
Benoy Abraham

Dear Benoy,

Without support, does CAESAR II show upward displacement at the point?
If not, I think you don't have to worry about compression.

And there are special hanger support can deal with compression load. Such as Rigid Strut.

Dear MK,

Thanks for your response..

In PSL UK catalogue maximum length (Pin to pin dimension) is around 6000 mm for Rigid Struts. In this particular case the Structural steel availability is at 8-9 m from Pipe CL and hence, providing Rigid strut is not feasible.

The reason why I was trying to provide a Rigid support at this location was to provide some rigidity to the system as at all adjacent locations to this support spring hangers were used and since stresses in Expansion case were within 90% of allowable (without liberal) i felt it was ok to provide Rod hanger at this support location.

I had planned initially that if there was an issue due to possibility of Buckling of the rod hanger in Operating case then I would go ahead with Spring hanger instead...

As you had suggested I had checked and found that without the Rod hanger support the displacement in Operating case at this support location is in vertically downward direction only i.e. no uplift observed.

Thanks once again for your response.

Best Regards

Benoy Abraham