The purpose of design water head on the spray water injection line to the desuperheater

[Heonli]

Hi, I have a query about ASME B31.1.

Cluase 122.4 (A.6) "It is recommended that the valve and piping be arragned to provide a head of water on the downsteam side of the stop valve"

I want to know the reason or purpose of that recommendation. If the water is in the downstream of the valve, does it prevent the heat transfer and protect the carbon steel valves and piping? Even the pipe is connected directly to the desuperheater.

 

[Dhurjati Sen]

Dear Heonli,

If not water (BFW), what else? Air (O₂) would lead to corrosion.

Regards.

DHURJATI SEN

https://www.nace.org/people/dhurjatisen

 

[davefitz]

The design temperature of the superheater spray header may be very high ( 1000 F, 540C) requiring creep resistant piping and valve materials for the spray control valve unless a water seal is provided in the fashion of a water P-trap on the downstream side.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick