5 replies to this topic

[harshchem55]

Dear All,

 

 

 I am actually sizing the inlet and outlet line sizes for the pressure safety valve. This sizing is required to know the correct selection of the psv type whether conventional type or pilot operated type. Referring to API RP520 Part I i have actually calculated the the orifice sizing. Please guide me further on how to size the inlet and outlet lines. I know there are some factors to be considered during the sizing of the lines i,e the velocity is limited to 0.5 mach; and the pressured drop in PSV inlet must not exceed 3% of the set pressure. Please help me which formulae to be used for calculating the mach no and for the pressure drop calculation.

 

Waiting for yours suitable guidance on the same.

 

 

Thank you all.

[fallah]

Hi,

 

API 521 included some guidelineds regarding PSV inlet/outlet lines sizing...

[shvet]

You can save time and calculate inlet/outlet lines using manufacturer's software. This one is rather simple.

[harshchem55]

Hi,

 

 

Thanks fallah and shvet for your inputs.

 

I have referred to API-521 Standards for the PSV sizing; Referring to equation 23 of this standard for calculating the outlet Mach number we need to input the outlet pressure. Please confirm which value i need to input for the outlet pressure. Outlet pressure w.r.t the PSV releiving pressure including overpressure (or) the back pressure existing at the PSV outlet common header which is going to the flare header.

 

Also what should the outlet mach number limited to.

 

Please guide the same.

 

Thanks.

[harshchem55]

Dear All,

 

I am waiting for your inputs on the same.

 

Thanks,

 

[serra]

I would suggest to read API, if there is piping you need to evaluate pressure drop at specified conditions,

in case of doubts better to ask an expert to do the work.