EQUIPMENT NOZZLE RATING

[Bahman07]

HI
I have problem to determine the nozzle rating for equipments. I work in piping dept., when I receive Process datasheets for drums, exchangers and towers from Process dept. and I have to determine the nozzle ratings. The contradiction is that there is equipments with design pressure and design temperature (mention in Process datasheet) less than connecting process line. With this conditions, shall I assume all nozzles with the higher rating? or I can just consider the connecting nozzle with higher rating and the others as per less rating?
Thanks in advance

 

[1503-44]

Large equipment is often comprised of hundreds of individual items, each having unique allowable pressures. The equipment allowable pressure cannot be higher than the lowest allowable pressure of all components. You should never assume that the allowable pressure, or the pressure rating of any component, equals the overall equipment pressure rating. It must be at least equal, but it could be considerably higher. If there was a design error, it might be lower, in which case you should report the error immediately. Likewise any pipe connecting to the equipment may also have different pressure ratings, higher, or lower, than the equipment to which it is attached.

So, nozzles attached directly to the equipment should have a pressure rating at least equal to the rating of that equipment, but will probably be somewhat higher. Whatever else connects to those nozzles may have the same rating, but could also be entirely different, higher, or lower. Best to not assume anything and fully research the pressure rating of each and every item.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[MJCronin]

Have a discussion with the responsible process engineer.

Do "piping line lists" exist for your project ?... If so these would contain the maximum operating temperatures and pressures that the system should ever see

Can the system, as he has designed, ever reach these higher temperatures and pressures ?

There is no sense in designing for conditions that the system can NEVER UNDERGO !!!

Oh, wait .... your boss has told you that you cannot talk with the process engineers ?.... Correct ?

MJCronin
Sr. Process Engineer

 

[mk3223]

The contradiction is that there is equipments with design pressure and design temperature (mention in Process datasheet) less than connecting process line

This is the good question to both Process and Piping to clarify the actual design conditions as required. There is no reason for the Piping to have the connected pipe to be one pressure rating higher than the equipment nozzle as required per its process condition or MAWP. But, it could be the case that the higher pressure rating nozzle is needed for connecting the specific instrumentation or device.

 

[1503-44]

There are many cases, especially in pipeline and field production and gathering work where pressure of the wells can be very high and piping pressure drops are very large, so upstream pressures are often considerably higher than downstream piping, units, vessels and equipment, thus it is not uncommon at all to have piping rated for pressures far higher than connecting equipment.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.