Pipe mating to pump flange 1

[JohnWeal]

Where an 800mm pipeline connects to a pump discharge flange, I want to specify to the piping installation contractor the acceptable tolerance for the holes lining up on the mating flanges so as not to pre-load / stress the pump flange.

The nearest I can get the pipe support to the pump is about 2m. With the mass of pipe in effect cantalevered towards the pump flange, there will be a difference in empty and full pipe deflection.

Is this what is referred to as 'sand-bagging' to artificially create a similar effect to the pipe being full of water?

Regards
John

 

[desertfox]

hi John

The piping installation contractor shouldn't need you to specify a tolerance to prevent putting stresses on the pump flanges, he should have enough experience to know whats expected on a pump installation, if they don't find someone who has.

However if you look at the pump and pipe flanges the maximum amount of misalignment should be no more than half of the clearence between the bolt and the bolt hole, that way the pipe doesn't part any stress to the flange via the bolts.
In other words if and when the pipe flamge is offered upto the pump flange it shouldn't have a hairy armed fitter levering the pipe flange across to enable someone to position the flange bolts in situ.

desertfox

 

[pennpiper]

Duplicate posting, not good.

prognosis: Lead or Lag

 

[pennpiper]

We should be very careful suggesting the use of "a rubber 'compensator'" until we have more data.
We only know the size in this case 800mm (32"NPS)
The OP has not given us:
- the Operating Pressure
- the Operating Temperature
- the Commodity
- the location/ambient conditions
- the type of Pump (Side suction/side Discharge multistage, double suction, horizontal split case?)

All of these will have a big impact on the possible recommendation of "a rubber 'compensator'"

John Weal, do you want to share any more information with us?

prognosis: Lead or Lag

 

[JohnWeal]

Hi Pennpiper,

The pumps we are purchasing are Hidrostal M700. Vertical installation, single stage screw impeller pump.

Duty: 1571 litres / second at 19.4m head.
Medium: Raw sewage (notorious high rag content due to long flat sewer network)
Temperature: fairly constant say 10 to 15 deg C.
Installation is indoors in a drywell location.
8 pumps in total each with individual riser to a discharge location.

Regards
John

 

[pennpiper]

The 800mm is the size of what?
- the size of each pump discharge nozzle
or
- the size of the main header after all 8 pump discharge are joined?

My opinion at this point is DO NOT use Rubber Flex Joints in this installation.

prognosis: Lead or Lag

 

[MikeHalloran]

On reflection, and revelation of a bit more information, I too would be disinclined to use rubber elements in a sewage line, because of potential (conjectural, I admit) glass content.



Mike Halloran
Pembroke Pines, FL, USA