1 reply to this topic

[SL89]

The tables in API 526 limit the PSV set pressure to below the flange rating limit in many cases, especially for higher flange ratings and larger orifice sizes. For example, for 600# CS conventional valves, L, N, P orifice relief valves are limited to 1000 psig (M is 1100), R is limited to 600 psig and Q is limited to 300 psig. For the Q orifice example, it seems like the valve would never have an application.

 

Does anyone know why such limitations exist?

[fallah]

The tables in API 526 limit the PSV set pressure to below the flange rating limit in many cases, especially for higher flange ratings and larger orifice sizes. For example, for 600# CS conventional valves, L, N, P orifice relief valves are limited to 1000 psig (M is 1100), R is limited to 600 psig and Q is limited to 300 psig. For the Q orifice example, it seems like the valve would never have an application.

 

Does anyone know why such limitations exist?

 

SL89,

 

I think in larger orifice sizes, the actual pressure rating is not achievable due to the limitation of available spring design.