Buckling Pin

[causeandeffect]

hello,
can someone provide me with an "idiot's" guide to sizing BUCKLING PIN or is it same method as sizing for PSVs or bursting disc ?
cheers

 

[MikeClay]

A buckling pin device can be treated as a PSV or a rupture disk. ASME Code Case 2091-3 spells out the requirements for the buckling pin device. The vendor's web site has a copy of this code case and additional material at

http://www.rupturepin.com.

Traditional sizing techniques can be used to size the buckling pin device. The following differences should be noted:

1. For low pressure devices, the orifice size is the normally the inlet nozzle ID, not an API orifice size.

2. High pressure devices may be one off designs. Contact the vendor for sizing help.

3. A starting point for the discharge coefficient is 0.62. An earlier version of the code case specified this value, but the current version relys on the vendor's stamped capacity.

4. Pressure balanced versions are available for high static backpressure situations.

5. Not all bucking pin devices from the above vendor are stamped per the ASME code. This requirement may have to be added to the valve order and of course, you will pay for it.

--Mike--

 

[pleckner]

First determine the controlling relieving scenario for your system. This is totally independent of the type of relief device you will select.

If you want a rupture disk, this should be sized as if it were a part of your piping system using the vendor's certified Kr. This method is commonly called the "Resistance to Fow" method. The Buckling Pin is related to a relief valve. To get the proper coefficicient of discharge to use in sizing, you need to discuss this with the vendor. I would strongly resist using a generic coefficient of discharge as this can lead to either a grossly undersized device or a grossly oversized downstream piping and/or collection equipment system.

 

[MikeClay]

The code case indicates that the buckling pin device may be stamped with either the UV, or UD stamp and gives the sizing methods for each case. To me, this indicates that it can be treated as either a relief valve or a rupture disk.

I agree that the vendor should be contacted for the appropriate Kd, but in all of my dealings, the vendor quoted 0.62. For initial sizing of low pressure buckling pin devices early in a project, this assumption is normally sufficient. Vendor certified calculations should always be requested, and if the buckling pin device is used to protect an ASME vessel, it should be stamped according to the requirements of the code case.

--Mike--