thermal relief valve - liquid tube rupture scenario

[fortywinks]

Hi..I hope I've posted in the correct location.

Has anyone encountered TRV sizing for liquid tube rupture scenario, meaning, the shell design pressure is higher than the tube design pressure.
Both shell and tube are of liquid type.

For a tube design pressure of 13 barg and shell design pressure of 25 barg, is it safe to assume the tube rupture is caused by a pinhole leak in order to determine the required relief rate?

The shell max operating pressure = 9.5 barg while the tube side max op. Pressure = 5 barg.

Which type of tube rupture assumption should I consider, as there are a few possibilities according to API 521.

And, what type of equation should I use to determine this liquid relief rate? One of my colleague suggested to use the equation in Crane. Does anyone know of any equation from GPSA?

I'm looking forward to more suggestions by fellow engineers who are more experienced in this as it's my first time sizing this scenario. Most of us here rarely encounter this scenario so it would be a gud learning curve as well.

Appreciate all your knowledge sharing, thank you!

[Techwus]

I do not have my books in front of me, but I think the Crosby manual shows how to size for those scenarios. Pentair also has a program that can help you size a PSV as well
You can try modeling the break as a sharp opening, or just model the full rate out of the tube for the worst case

[saplanti]

I suggest you check your system for brittle fracture with a process engineer.

[izadi]

Hi
First step of PSV sizing is calculating the relief load. API521 describes the method of calculation. you should consider one tube rupture at tube sheet joint. then calculate the maximum flow from shell to tube, from shell to tube channel and from shell to a long ruptured tube. the mentioned hydraulic calculation is a little complex but by using a software like "korf hydraulic" you can do it easily. feel free to ask if this brief advice doesn't help you.

[udokas]

thanks