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[Khu]

Hi all,

 

I have a case whereby the operating temperature of the discharge of the compressor is 180°C.

 

When I trip the compressor, the maximum temperature of the discharge of the compressor has reached 210°C which has exceeded the design temperature of the pipeline of 200°C.

 

However the temperature only exceeds the design temperature for a duration of 0.4s.

 

My question is are there any API or ASME standards out there which justifies that the pipeline is capable to absorb the short duration increase in temperature (similar to how incidental pressure can be 10% above the design pressure due to surge)?

 

Thank you in advanced

[ankur2061]

Khu, 

 

Design Temperature and Design Pressure are not independent entities for a pipe of a given rating. Both are interdependent. An increase in temperature derates the pipe in terms of pressure. ASME B16.5 gives tables of pressure-temperature rating for different pipe pound ratings and pipe material class.

 

Let us take an example of a 600# rating pipe for Material Class 1.1 (CS) based on ASME B16.5

 

For a design temperature of 180°C the corresponding design pressure would be 88.9 barg

For a design temperature of 200°C the corresponding design pressure would be 87.8 barg

For a design temperature of 210°C the corresponding design pressure would be 87.1 barg

 

Let us consider another example of a 300# rating pipe for Material Class 1.1 (CS) based on ASME B16.5

For a design temperature of 180°C the corresponding design pressure would be 44.4 barg

For a design temperature of 200°C the corresponding design pressure would be 43.9 barg

For a design temperature of 210°C the corresponding design pressure would be 43.5 barg

 

If you see the above data, the difference in the pressure rating between the temperatures 180 to 210°C is very small.

 

Hope this helps.

 

Regards,

Ankur.