Nominal pressure of liquid ammonia pipelines
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For the liquid ammonia pipelines connected to spherical tanks (at normal temperature and medium pressure), should the nominal pressure be set at 2.5 MPa or 4.0 MPa?
At 4.0 MPa, the saturated vapor pressure of liquid ammonia at 50°C is primarily considered.
It depends on what the design pressure of your ball tank is, just my personal opinion!
The equipment specifications require that the connection flanges of spherical tanks must be of a grade of at least 4.0 MPa or higher. The design pressure for liquid ammonia is generally 2.16 MPa, and a pipe grade of 2.5 MPa is sufficient to meet this requirement. Depending on the actual circumstances, given the frequent occurrences of ammonia leaks these days, it is safer and more reliable to choose a grade of 4.0 MPa if the necessary investment can be made
Thank you all for your replies. There is another question I don’t understand: why is the design pressure for many storage tanks containing liquid ammonia at room temperature set at 2.16 MPa? According to TSG R0004-2009, the saturated vapor pressure of liquid ammonia at 50 degrees is 2.03 MPa, and this value should be used as the operating pressure. If the design pressure is set at 1.05 to 1.1 times the maximum operating pressure, then the design pressure should be at least 2.13 MPa to 2.23 MPa. It’s unclear why 2.16 MPa is chosen as the design pressure
The equipment specifications require that the connection flanges of spherical tanks must be of a grade of 4.0 MPa or higher. Which specification specifies this?
The design pressure specified in the original regulations has been changed to operating pressure in the new regulations; therefore, I believe that the design pressure for liquid ammonia can no longer be set at 2.16 MPa
There have been many accidents involving liquid ammonia or ammonia gas in recent years; setting the pressure at 4.0 MPa is beneficial for owners, design firms, engineering companies, and safety supervision agencies, and the additional investment isn’t significant either:handshake