Nozzle loads

[maintennance]

For one of the charge pumps in a refinery plant, as per the licensor P&ID, the line size is 12 inches where as the pump offered by the vendors is 6" suction and 6" discharge ( TOP-TOP). Can there be so much difference between the suction line and the suction nozzle size selected by the pump vendor? What are the criteria to follow to decide on the nozzle size of the Pump. As the service fluid is for high temperature ( around 300 deg C). Because of this the nozzle loads to the pump is also getting increased and we have not yet approached the pump vendors to check for the possibility of increasing the allowable nozzle loads for the pump suction and discharge from the 2 times of API 610 load values. Is this the correct approach. The pump rated capacity is 220 m3/hr and the discharge pressure is 37 barg. Thanks to clarify.

 

[BigInch]

Seems strange to have such a difference in diameters. Is it a high speed pump? Actually 6" seems low and your plant's 12" seems just a bit high. I would think 8 pump nozzle and 10" plant piping might work out better.

I doubt you'll make much progress trying to get the pump vendor to change the allowable loads. Work towards adding expansion loops and other stress solutions is likely to be more productive.

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[micalbrch]

Agree with BigInch. 6" is small for 220 m³/h. That leads to a fluid velocity of around 3.5 m/s - pretty high on the suction side.