Dear all,

Most of the client, considered the nozzle load for pump and temperature shall be operating temperature. Can some one guide me. why we not considered design temperature for nozzle load qualification.

1) " For Rotating Equipment (pump and compressors), Operating temperature will used for nozzle load qualification.

Why consider something that will NEVER happen?

Dear Jop,

I cant get your question.why consider something that will never happens means?

My question:

For Rotating Equipment (pump and CompressorS), Operating Temperature will be used for nozzle load Qualification.

As i checked for both the conditions operating and design. If we follow the design condition nozzle exceed the allowable and thermal expansion.
For eg. Pump design temperature is 120 deg c and operating temp is 80 deg C. In which condition, we have to qualify the nozzle load for rotating equipment.

thanks

Shabeer,

You need to discuss this with your Process group to find how they derive design conditions. Some firms use the max operating, others for instance, add an arbitrary 30 deg C to the max operating. As Jop correctly adds, this cannot exist. It would only be relevant to material selection, not nozzle loads.

There have been many posts on this issue, try using the Search facility for further words.

Process engineers are the primary creators of pipe stress problems.

If you can, try to get a copy of the data sheets used to purchase the pumps. Those will typically tell you the truth of what the pump will be operating at.

As MoverZ astutely pointed out, "design" is often an inflated number (temperature and pressure) intended to insure the wall thickness calculations are conservative enough. While they typically have little to no impact on the selected wall thickness, their artificial nature can have a big impact on the stress analysis, particularly where strain sensitive equipment is concerned.

MoverZ has correctly stated, design temperature is mostly derived by adding some margin to operating temperature. The reason many process engineers also don't know.

This is the reason most client ask to perform nozzle load check at operating or max operating temperature for ratating equipment. Rotating equipment are load sensitive and allowable nozzle loads are low with compare to static equipment. The extra margin on operating temperature will result in unrealastic loads on nozzles and will result in some extra pipe run, elbows or springs to solve it.

Design temperature is an old days concept which was used basically to calculate the wall thickness when stress analysis was not done so extensively. Nowdays I have seen many companies using maximum operating temperature for stress analysis. Many times we have to educate process engineer for implications of "non existing" conditions on piping and stress analysis.

Regards,

I've experienced this to one of our projects that we've worked before, this will lead to uneconomical design, totally a disaster. We have learned that this will not happen in reality. Totally waste of money and time.

Regards,

Clyde