NH3 refrigeration plant Mexico; Design Pressure

[virk]

We have the order for an NH3 refrigeration plant for the south of Mexico. We need to know the required design pressures there for as well low pressure section as high pressure section.
(We have agreed that the design code for pressure vessels to follow will be PED (European Pressure Directive).
(If we followed German rules, 16 barg high pressure and 12 barg low pressure section would be sufficient.)
Does anybody know about this and can provide us with additional information?

Regards virk

 

[virk]

Nobody has an idea?

Probably the minimum design pressure in the United States could also be helpful because we heard that Mexico often follows American rules.

Any support kindly appreciated!

Kind regard

virk

 

[HEC]

Virk,

what are the local storage temperatures hte vessels will be exposed to. Both high and low. From these temperatures (wiht some margins) the stauration pressures will give the design pressures required.

Mark Hutton

 

[virk]

Thank you Mark.

The system will condense the ammonia at 14 bars absolute and the low operation pressures will be 0,28 bars absolute and 0,35 bars absolute.

I think I need a hint to any specific requirements there in Mexico.

Regard

virk

 

[HEC]

Condensing temperature/pressure is one thing, but what is the expected ambient temperature and solar insolation loads expected. From a material strength poinit of view what is the minimum ambient temperature (cold embrittlemnet issues).

Mark Hutton

 

[virk]

1) Let us assume the expected (maximum) ambient temperature is 40°C and there will be no insolation from solar radiation; the plant will be installed into steel frames outside.
2) Minimum ambient temperature is -10°C. Why this is important?

Regard virk

 

[HEC]

from the previous post you are expecting to condense at 38-40C, Storage at 40C gives saturation pressure of 15.5 Bar, to allow for extreme design around 45C storage temperature. This is a 17.4 Bar saturation pressure and hence the design pressure. Minimum temperature will affect minimum thichness and material selection against cold embrittlement.
Note of caution as the whole system will at some stage be exposed to the higher temperature while charged with amonia and allowed to come to ambient temperature, the whole system should be designed to the higher pressure i.e. 17.4 Bar.

Mark Hutton

 

[virk]

Thank you Mark! We will design high pressure as well as low pressure section for 18 barg.

Regards virk