Say, after developing suction & discharge piping & supporting digitally through Caesar-II modelling, we arrive at site.

As there are few estimated inputs like weight of piping, insulation, flanges & valves, temperatures of trunnions, vessel skirts, idealistic standaby/operating pump temperature consideration, guide/stop gap, value of friction etc, if pump commissioning people tell that pump piping loads are high, which options are available at site ?

If springs are available near to pumps, we can alter load within limits, adjust the height of adjustable supports, add/relocate some supports/springs, reduce friction at supports by introducing low friction pads - what else ?

regards,

sam

Personally I would first ask why they think the loadas are high and ask if they think the loads are too high. Loads can be high, but as long as they are not too high, why do you want to make changes?
I once had a costumer that said pipe stresses and nozzles loads were high (both about 70% of allowable). 70% of allowable however is approx. 70% of 66% of yield stress, which is approx 50% of the load it can technically handle.

If you need to lower the forces there are a lot of options, springs, small adjustment of pump location (only mm, often possible with pumps) friction in supporting and so on. You have to remember though that you're calculating a theoretical situation only and that the forces in field will always be different from the calculated forces.

Thanks for reply. You are right. We must not accept fault, unless we are guilty. There can be many reasons for pump misalignment.

I shared my limited understanding here to learn from our experienced mentors in this forum.

The situation in field is expected to differ a bit from digital model in Caesar-II as some of the deficiencies in piping & supports like guide/stop gaps, support friction, cold pull made in joining up the pump flanges etc can't be estimated in design, beforehand. Under such circumstances, we, generally take risky decisions with some consciousness and knowledge about their potential future consequences, i.e., their futurity. Then, we measure the results of the decisions against expectations through systematic feedback over time. Any more exact way ?

I wished to have some opinion from our mentors in this forum on the extent of piping stress walkdown performed by them for typical process pump piping supports.

It is understood that the extent depends on situation & types of load cases considered regarding working/standby pumps. But, walkdown of supports in piping system section that are totally irrelevant to pump piping forces - deadweight/expansion/occasional, but just for the reason of the presence of the same in piping stress package may be a wastage of resources.

For example, for Gustav, one may blame global warming caused near the east of US, not the one caused by China; Isn't it true for pump piping stress walkdown audit, too ?

regards,

sam