Centrifugal Pump Design

<...How good is using tap drilled mounting plate for installing pump motors and how to design it?...>

It's ideal. Use the motor manufacturer's published information to design the mounting plate.

you must take accurate alignment position into account for the tapped drill design, your holes must precisely in position so that you do not pick up difficulties during coupling alignment.

while slot base plate you can have a room for adjustment.

Hi, You can use channel base for mounting pumps with slotted base bolt holes both for pump & motor. It gives you flexibility to alignment and renewal of base bolt, if required, specially for high capacity pumps.This is the advantage of use channel base over base plate and tapped base holes. You can weld stiffner ribs to the base channels to strengthen the base.

Thanks for your inputs. Actually, I am getting only 40mm gap between the motor foot and top of baseframe grout.

The only option that seems feasible is putting a tap drilled 40mm plate (37mm for plate + 3mm for shims) and assemble the motor. My worry is how good these 4nos 40mm plates withstand a 3.6 MT motor having 1500 rpm speed?

Hi Vishal, I think 40mm alloy steel plates will work. But shim thickness should not exceed 2.5mm. The base plates to be all welded with channel baseframe and base bolts should be M38/M40.You can enlarge or make elliptical the motor foot holes for ease of alignment. Max. radial misalignment should be within 0.05mm & so axial misalignment for your pump. What type of coupling do you use for this pump? Flexible type flanged coupling with multidisc spacer will work good, I think.

couldn't agree with you more in this regard,Flexible type flanged coupling with multidisc spacers will definetely work, laser alignment will prove fruitfull for this application.

Once again thanks to you all for valuable suggestions!

I have ISMC 250 channels in baseframe for to which I am afraid these alloy steel plates could be welded, otherwise for SA 193 Grade B7 this could have been the best option.

Flexible type flange coupling is being used in this case.

Hi,Vishal. If you have afried about alloy steel plates and welding techinque in this regard, you can use mild steel base plates to your required thickness. I think there will be no problem to weld it with your channel frame. Use good quality electrode like Vortic 16 of 3.15mm(12SWG) or higher.

you mentioned "baseframe grout";is this being reinforced?channel type or I-beams,with gassets? how wide apart is your motor holes pcd. now you will have a situation where your plate act as a beam with load applied on both ends, and it will tend to deflect in the middle, unless of course your baseframe is reinforced properly to carry the load and give the plate enough support to handle this load.

please ensure you sellect a correct type of material for bolts, that wont cease over time.

The situation I have is that of a centrifugal pump and its motor. The baseframe is a rectangular frame made of Channels 250X80, installed on RCC foundation by bolts. This frame is grouted after pump & motor alignment. Now change of impeller demands change of motor. The earlier motor had stools made of 25mm plates on which 50mm mounting plate was welded. The motor feet (4nos) have 1 hole 42mm dia each.

Center-to-center distance of these motor feet holes is 950 mm laterally & 1330mm longitudinally.

Motor feet will support on new 40mm mounting plates after chopping off the earlier stools and welding 40mm plates directly on baseframe channels in the new proposed arrangement.