Friends,
For the centrifugal pump nozzle we run API-610 qualification run if operating loads are higher than API-610 but under 2 times of it.
We dont think about Occational cases like Seismic and Wind.Only engineering judgment is considerd that occ Load should not be higher than the reasonable range compare to its size.

My queistion is that:
A)Is there any authorised documents that specify that we dont need to check API-610 run for qualifying the occ. loads on the pumps.
B)The value given in the Table 2-1A(SI units) and 2-1B(US units)
in API-610 are operating allowable loads or occational alloable loads?

Thanks in advance....
Subhankar
Kolkata

Check this previous post on the same subject.

My experience has been to try and qualify loads including occasional to the stated allowable, e.g API 610 or NEMA.
If you can successfully meet the allowables using standard pipe stress procedures that's great. If hydraulic snubbers are required or something else that is not a standard item then I would check with the client and ask their preference.

Dear Shubhankar,

Pls. note that API-610 gives guidelines for allowable external forces & moments on the pump nozzle flange. In actual case, you will never have only occasional loads acting in system. You will always have operating loads, for which the min. limits are specified in API-610. You can follow the same for combined load of occasional & normal operating load case (though this is conservative).

Alternatively, it is the best practice to get confirmation from the pump vendor or ask allowable loads from vendor for completeness of analysis.

Regards,
KVJ

[font:Lucida Console]Though all of us try to keep actual loads withing the allowables specified by the API 610 in all cases, but sometimes it becomes difficult in very large size pumps. Following are my opinions : API 610 allowable is based on wearing parts within the machine and not the occasional events. Pump is subjected to just operating loads all the times except in a rare instances of occasional loads. Such short-term occasional load (e.g. seismic) does not result in excessive wear of internal parts of pumps and leakage problems. At the max. it can cause misalignment, which is always checked and corrected after such rare occurrences like earthquake before start of the plant. Better approach would be to ensure proper supporting near pump to avoid possible damage in case of earthquake. Many plants have tripping mechanisam in case of earthquake. that means pumps will be immediately stopped in such events. Pumps being at very lower elevation are also not much susceptible to wind. API 610 interpretations clearly stated that checking pump nozzle loads in operating conditions would not violate the intent of the code. however at another place they write THEY DON"T ADDRESS THE ISSUE. My opinion- in general code must specifiy such minimum requirements. Like all other TRs they can reply Yes or No. Don't they know how they arrived at the allowable ?? If they know they must have clear reply in terms of "Yes" or "No". Another issue with these codes is they will very often put words like "Subject to owners approval" . E.g. Use of appendix F of API 610, Clause 302.2.4 (f)of ASME B 31.3...How many of us actually go to owner and ask for approval for using this clauses??? So even if your vendor allows you to use higher loads, you cannot even exceed 1 time the table value if your owner do not permit it. [/font] :crazy: So first of all try to bring withing the allowable. if it still exceeds slightly in occassional cases, instead of playing number games by adjusting gaps and supports by few milimiters, it would be best to ensure good supporting and our own judgement. [/font]

Thanks to Tushar,
I am fully agree with you!!!
i have already sent my justification(As you told) to our client..
and they slill not responding...
so i think the issue is clear to them..
One lesson i have learned from this.. we should mension in Stress philosophy at the strating of project that we are going to check loads comming in to the pumps with API for operating cases only. thats all....
Thanks to everybody for kind assistance.

My take is that do the pump calcs for the normal operating only.
The pump calcs are really only for running loads and i would ignore occational loadings as the y will have no effect on the wear of the machine.
However, large Occational loads may well damage the pump itself.
this were judgement would be used.

(much the same as all)!