Hai Dev

We are trying to solve a case where there are 4 pumps in which 3 pumps are operational and 1 pump is standby, the piping network of the pipe connected with the pumps is shown below (please view image from link 1)

as the P-01 is stand-by we have given ambient temperature and operating pressure to the line connected to the pump up to "T " as shown in the fig( pipe marked with red boundary ), and the load cases are given as shown (please view image from link 2)

when , we are doing API 610 analysis there is no difference in forces exerted at anchor near stand by pump and other operational pumps. L4 is considered for Standby pump and L3 is considered other operational pumps.
Please advice weather these load cases are correct for this condition and the pipe inputs we gave for the pipe connected to standby pump (temperature and pressure).
Also, I have a small query about the same case ,at the primary stage of the analysis i.e before modeling the pumps we observed forces of 213 KN (-Z as Z is vertical in our case) and some force in X and Y directions at anchor which is connected to the nozzle flange but when we modeled pump the forces are very small around 500 N in -z direction and zero force in x and y directions ,what could be the reason for that?
http://s38.photobucket.com/user/ajju5432...html?sort=3&o=0

[URL=http://s38.photobucket.com/user/ajju54321/media/load%20cases_zpsp8sh956q.png.html]


Thanks in advance

Please click the "switch to full reply screen" button and upload your image directly to the forum. Some of us can't see the image you're trying to share.

[img:center]http://s38.photobucket.com/user/ajju5432...html?sort=3&o=0[/img]

[img:center]http://s38.photobucket.com/user/ajju54321/media/load%20cases_zpsp8sh956q.png.html[/img]

If u still con't access to the images, please share your mail id if its possible so that i can mail the images.

Thank you

See if these instructions help.

If not, I can be reached at my first name DOT my last name at gmail.

Thank you Michael Fletcher, Its very helpful

Your load cases shown appear correct, though incomplete. You'll need additional 19 load cases for occassional cases

L19+L5
.
.
.
L32+L5

and you're missing expansion cases

L2-L4
L3-L4
L2-L3

I can't tell from the screenshot, but I assume those pumps are anchored from the center. I can only see CNODE anchors at the two nozzles.

Double check the pump drawings to see where the pump is supported and from where it grows, and place the hard anchor accordingly if you have not already done so.

Hai Michael Fletcher,

I am very thankful for your advice regarding Load cases and i have updated the cases in my work.

Initially,in the trail run without modelling equipment we got forces in all the directions(x,y,z) and especially 120 KN in -Z direction,but once i modeled the pump the forces have reduced to 500 N in -Z direction and 0 in x,y directions, What may be the problem,is that with my equipment modelling.

My main concern was in API 610 analysis,The forces near the discharge and suction points are same for all the 4 pumps (both operational and stand-by pumps), is that because of my equipment,please advice.
please refer the attachments and advice suitable corrections if any


Thanks in advance

When you use an anchor, +Y, or any other support, you're fixing your pipe to a point in space.

When you use a CNODE on an anchor, you're fixing your piping element to a point on another piping element. If that piping element (in this case, a pump), itself is not anchored to a free point in space, then it is merely dangling from its nozzles.

You should instead have one of the following two situations:
A) an anchor point in the middle of your pump, or
B) an anchor point located at the base plate of your pump, in which case, you should have a third element going from the middle of your pump down.

Generally, when you model a pump in CAESAR, you may see a modest reduction in moments on the nozzle and an increase in axial loads on the nozzle.