6 replies to this topic

[rowanlim]

Hi all, I'm currently sizing PSVs for a fuel gas heater using hot oil as the heating medium. My calculations reveal that a size J orifice is required for tube rupture case. However I would like some input on the necessity of installing a buckling pin alongside the PSV. Is this a common practice & how do I determine the sizes of both the PSV & pin? I wonder if we could use either one of the PSV or the pin instead of both together.

Attached is a diagram illustrating the location of the PSV in relation to the heaters. I appreciate any feedback, thanks!

Attached Files

•  PSV.bmp   733.61KB   46 downloads

[Erwin APRIANDI]

Hi Rowanlim,

Refer to your diagram, what is PSE? is it the bukling pin?
and is the bukling pin that you have mentioned is refer to a rupture pin?
and any specific reason why you have to installed both?

A rupture pin is designed to be a non-reclosing pressure relief device, similar to a rupture disc

What I know, the installation of rupture pin is before the PSV, which can help us in:
- Protects PSV from pulsation and fatigue
- Bubble tight seal until set point
- Extends the life of the PSV

and rupture pin can also be use as a non reseting pressure relief method, so I think you can choose either one of (PSV or rupture pin) if the istallation of PSV and rupture pin is in paralel (PSV is more preferred to be installed)

I also attached an article related to rupture pin

Attached Files

•  Rupture Pins.pdf   26.19KB   79 downloads

Edited by erwin.apriandi, 16 March 2011 - 03:40 AM.

[paulhorth]

Erwin,

Your diagram shows what I refer to as a Buckling Pin valve. There once was a different type of device which used a pin which ruptured in shear mode, and these were at one time referred to as rupture pins.

These Buckling pin devices are the right choice to protect exchangers from overpressure due to burst tube. A PSV will not react fast enough to prevent a pressure spike. A bursting disc will open fast, but bursting discs have many disadvantages compared to buckling pins. They are prone to bursting at too low a pressure, and in this case that would result in dumping all the hot oil into the flare system. This actually happened on a plant that I was involved with, and there was a delay in operation while a new supply of hot oil was shipped in.

I agree with you that Rowanlim does not need to fit both the buckling pin and the PSV. Just use a size J orifice buckling pin valve.

Paul

[rowanlim]

Thanks for the replies, Erwin & Paul, I also wondered about the redundancy of having both a buckling pin & a PSV installed together.

I do want to know, when do we install both the buckling pin & the PSV together? Is it a common practice?

[Erwin APRIANDI]

Dear rowanlim,

Concerning to your questions?
"I do want to know, when do we install both the buckling pin & the PSV together? Is it a common practice?"

From what I have seen both buckling pin and PSV can be installed together in series, means you installed buckling pin at the upstream of PSV to
- Protects PSV from pulsation and fatigue
- Bubble tight seal until set point
- Extends the life of the PSV
But I never see it is installed in paralel.

And as Paul has explain further about buckling pin, that it is preferred for protection of exchangers from overpressure due to burst tube rather than PSV. So I think in your application you can use buckling pin instead of PSV.

Since buckling pin is also accepted by
- ASME Section VIII Division I Code Case 2091-3
- API RP-520 Part One – Section 2.4
- The National Board of Boiler and Pressure Vessel Inspectors

so it can replace the need of PSV for protection of pressure vessel

[rowanlim]

Thanks for your response, Erwin, I now understand it better!

[fallah]

Hi all, I'm currently sizing PSVs for a fuel gas heater using hot oil as the heating medium. My calculations reveal that a size J orifice is required for tube rupture case. However I would like some input on the necessity of installing a buckling pin alongside the PSV. Is this a common practice & how do I determine the sizes of both the PSV & pin? I wonder if we could use either one of the PSV or the pin instead of both together.

Attached is a diagram illustrating the location of the PSV in relation to the heaters. I appreciate any feedback, thanks!

Spring loaded type PSV is slow acting pressure relief device compare to rupture disc or buckling pin.

IMO,the PSE (as buckling pin) in the diagram would be a proper back up for the installed PSV.The PSV would handle the normal overpressure as reclosing pressure relief device that is preferred to other relief devices in this regard.
But PSV may not lift when it see pressure spike in such low compressibility liquid (Hot oil) and at this time buckling pin would be opened rather than PSV.

Edited by fallah, 03 April 2011 - 05:46 AM.