Relief Line Thrust Force Dissipation?

[simon17]

Hello,

My company is currently stress analysing a series of 36" vent/releif lines. The main relief line has a 36" rupture disc and also a 10" connecting branch line with a PRV. The design pressure for the line is 150 psig. Doing a simple thrust force calculation of F=P*A results in a very high force which is creating lots of issues for the structural group in restraining the pipe.

Since the vent on the releif line is significantly far away from both the PRV and the rupture disc, it is assumed that the pressure from the popping of either item will dissipate prior to reaching the vent and not exit the system at the design pressure. Is there a way to calculate the pressure loss through the system?

Regards,
D

 

[DSB123]

Yes there are methods to calculate the pressure loss through the system and this should have been done by your Process group to ensure the backpressure at the bursting disc and the RV are acceptable and this is how they should have determined that the pipe size is acceptable.

 

[ZDawg]

Good day,

I'm trying to model the thrust force due to a relief valve. I was wondering if when I run the analysis in CAESAR, should I remove the pressure load in the operating case? Or should I determine the pressure gradient away from the relief valve first.

I have a 42" PIG Launcher system operating at 120F and 1440psig and am looking for the effect of the relief valve, which faces straight up, on the pipe support pedestal. The pipeline is using natural gas and I have already figured a maximum thrust force of around 250kips.