Re: [PipingDesign] Failure on Relief Valve

>On my project , I have the problem on relief valve system. Now the bolt on
>the upstream and downstream all is loosen due to vibration. The set pressure
>is 68.9 barg and the size is 6" x 8".
>How to calculate the force reaction when the relief valve popping ?
It works like a rocket. The force on the relief valve equals the change in momentum of the fluid going out. Check your fluid mechanics textbook.

>How to design a good support to protect the loosing bolt cause by vibration
The relief valve flange has been designed for the necessary loads by the manufacturer. The bolt probably came loose because it wasn't torqued properly. If the flange bolts don't need to be removed periodically, you might want to stake the threads, otherwise use a thread locking compound (Loctite) when you assemble it or one of the many locking fasteners.

>How to check the strength of flange on bolt due to reaction force on relief
>valve?

Figure the thrust load then and calculate the pressure equal to the thrust divided by the area of the flange bore. Add this equivalent pressure to the flange design pressure and use the result in the ASME Code flange calculations. This is conservative, but not enough to hurt.

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw@skypoint.com        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)