Dear All,

Shall we take advantage of friction coefficient 0.1 (Steel to PTFE) instead 0.3 (steel to steel) to reduce the stress range for Design maximum (Positive) to Design minimum ( Negative, if it helps.

In a long length of piping , using the Friction coefficient 0.1 at the branch piping reduces the stress range.

Please suggest.

Thanks

I've only heard that you shouldn't rely upon the existence of friction loads to meet code compliance.

I've never heard that you shouldn't take credit for the lack or reduction of friction loads, particularly if it's intentional.

Friction can only be counted on to make things worse. The actual value of mu changes with the age of the system and the specific condition of the surrounding environment. Even with your "best guess" at mu, you can still be off + it - 50%.

I think this needs to be printed on the label of the Caesar II install disc...and probably included in the rotation of those "tips" that pop up at startup.

Hello Richard.

I think that it's very difficult to generalize the effects of friction.

This is my understanding about friction:-

1. Expansion stress-Severe when friction is active. Reason is quite obvious since we are restricting expansion.

2. Occasional Wind stress-Severe when friction is active. If friction is not active then piping can slide and transfer the wind loads to guide. However, if friction is active then pipe itself will be stressed.

3. Seismic wind stress-Severe when friction is not active. If Piping can vibrate freely in case of seismic movement, the stress will be higher.

4. Nozzle Loads:-Severe when friction is not active. Since the piping can slide freely so the resulting moments on nozzle will be higher.

Please correct me if I am wrong.

Thanks