Hangars are generally only considered to act in the -Y direction. That is they
allow the pipe node to move in all other dierctions except vertically down. If
the support is double nutted then vertical lifting in the +Y direction is also
inhibited.
If the pipe node moves in the X or Z direction there will be some movement in the Y direction. The hangar will swing radially. This displacement will depend upon the length of the hamgar (ie radius of the arc). If the hanagr rod is fixed then the rod will act like a cantilever to prevent sideways movement. The hangar rod is usually of a relatively small diameter and will not resist the pipe movement .
Hangars are not the best support to use when there is thermal movement as you have no control over the movement unless additional supports are provided. (sway braces, trapezes etc). It is difficult to guide or restrtain a pipe held on hangars.
In addition if there is any forcing frequency that corresponds with the natural frequency of the pipe then resonance with large displacements will occur.
In the earthquake and wind cases you will find that hangars do not serve you very well as the pipe will be displaced in an uncontrolled manner when horizontal loads and accelerations are applied.
When surge pressures occur long straight runs of pipe supported on hangars can be subjected to large displacements if the surge interacts with a boundary such as a valve or elbow. If one hangar fails due to overload then the adjacent hangars will be more heavily loaded and will likely fail and the whole line come down around your ears. Many a steam line has failed in this way.
Hangars are commonly used in building services because they are cheap and installers do not worry too much about codes and standards.
Geoff Stone
satish gunjal <gunjalsatish@yahoo.co.in> wrote:
Dear friends,
Please can anybody write in detail on flexibility & stiffness of pipe support(
Hanger type).
Regards
Satish Gunjal
JACOBS H&G PVT.LTD.
"Have a nice time"
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[Non-text portions of this message have been removed] Received on Tue Nov 29 15:36:00 2005
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