Hi friends,

I am doing the stress analysis of a 8 inch Liquid Flare line from a Heat exchanger. The cold condensate is in the shell side of the exchanger and hot gas is in the tube side of the exhanger. There is a flare line with a rupture disc in the shell side to protect the exchanger.

The rupture disc is placed about 4m away from the nozzle. Normally there is condensate liquid in this flare line upto the rupture disc. In the event of a tube bursting inside the heat exchanger, the high pressure gas leaking from the tubes, pressurise the condensate liquid in the shell and eventually the rupture disc bursts and the condensate liquid go through the flare line to the liquid flare header. Before rupture disc bursts the downstream side of the rupture disc is empty. The piping is about 15 meters in length with some elbows before it goes into the header.

according to the Process dept., when the rupture disc bursts the condensate flows through the pipe at a velocity of 154m/s.
They are saying we have to design the piping to cater for this speed.

I have the following questions.

1)Do I have to consider this as a slug flow event with a slug velocity of 154m/s ? If I consider this as a slug, the slug force that I am getting is extremely high!

2)What is the general approach that needs to be taken while doing the stress analysis of piping systems with high velocity fluid flow?

My sincere thanks to you all for reading this and waiting for some guidance.

Do not thake my words for granted but from what I know (and I don't know much, just to put the things straight), in case of tube rupture, fluid will flash, so there is not a such major concern of slug. You should study howerver if RD is appropiate for this as it will not close anymore, so you will continue to deinventory your system.

You will have some flow induced forces. Up to you how you will calculate this.

Regards,

154 m/s (505 ft/s or 345 mph) is definately too high per standard line sizing practices. Discuss with process to obtain a more resonable velocity by resizing the piping.