Hello stressers
can anyone explain exactly how thrust force affect on piping system?
and when should i include it in calculation of nozzle loads?

Thrust forces are generally neglected in steady state flow conditions in closed piping. Otherwise, non-steady state flow and open-atmosphere piping is when they are primarily applicable.

However, your question is so broad in nature that to answer it would require an entire book.

Thank you Michael
ould you please recommend a book or article to read about this issue?

Of course, the technical resources provided with CAESAR are one place to start. Searching through these forums might help, too.

API-520 describes steady state relief loads. It assumes that transient effects are much smaller than steady state. As long as your piping is short, this is true. There are plenty of resources on the internet that discusses this phenomenon.

ASME B31.1 appendices discuss special configurations similar to local vents.

LC Peng "Pipe Stress Analysis" does a good explanation for analyzing relief loads within closed piping, as well as other phenomenon.

Aft-Impulse software has videos, some I believe on youtube discussing water hammer. While not the exact same thing, it's often correlated.

Other scenarios you might hear about include sudden start/stop of pumps, rapid open/closing of valves, high pressure pipe rupture.

Shutdown Valves for pipelines are also subject to this.

Edit to add: You may also look for "imbalanced piping forces" which is often such an indicator of fluid thrust.

Also, to apply pressure thrust on the equipment nozzle, this thread could be helpful

http://65.57.255.42/ubbthreads/ubbthread...=true#Post56144