5 replies to this topic

[fatimah]

Hi mariusz

weird. the design temp is 100 degree and the relief temp is 170 degree. if suddenly the operating temp increased up to 120 degree, the vessel already in damaged. there's no point the relief temp is set at 170 degree. the vessel may not able to be used anymore.

[fallah]

Hello
The vessel is protected by PSV. The design temperature of the vessel is 100 deg C. The relieving temperature is 170 deg. during electric power failure.
I would like to ask You if the design temperature for vessel should be higher or the same as relieving temperature or lower design temp. is allowable ?. Please give me information on which base (API ? or something else) You consider answer.
Thanks for answers

What is relevant project criteria for determination of tanks design temperature?

If you mean electrical power failure would lead to,let say,e.g. air cooler in vessel upstream is failed,this scenario should had already been considered in stage of determination of equipment design temperature.

Please attach a simple sketch of your system to be able to provide better assistance.

Edited by fallah, 06 November 2009 - 11:00 AM.

hello.
the vessel design temp is related to process and related to PSV....even though at the relieving conditions temp is higher the design temp is not a matter...because the Wall temp of the vessel is 1100degF to capable of fire conditions upto certain time...See API520pt1 .....

[fallah]

hello.
the vessel design temp is related to process and related to PSV....even though at the relieving conditions temp is higher the design temp is not a matter...because the Wall temp of the vessel is 1100degF to capable of fire conditions upto certain time...See API520pt1 .....

As post originator mentioned: "The relieving temperature is 170 deg. during electric power failure."

Therefore the case is not the fire case and should be considered in determination of design temperature.

Capability of vessel resistance in pool fire case depends on the stress value (due to pressure) and mentioned in API 521 SEC. 5.15 (not in API 520).

[fallah]

Just to closing the issue:

In general,the design temperature of an equipment should be equal to or greater than the relieving temperature of its relevant PSV,but fire case is an exceptional case.