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Pump layout and mechanical handling

Pump layout and mechanical handling

(OP)
4 of the proposed pump stations we are proposing don't seem to be right to me.

We have a horizontally split case pump where the drive shaft is vertical but the impeller is horizontal.
The inlet and outlet are horizontal and are 700 and 400 pipe size respectively. The actual inlet and discharge pipelines are 800 and 700 using reducers. The motors are betweeen 1.2 and 2.1 MW so are in the region of 8000 kg each. The pump is 4000 kg.

The arrangement is that the pump is on a plinth in the basement and the motor is sat on the floor above which is something like 5m above the pump floor level. A short approximately 2.5m shaft connects the motor to pump.

So, to remove the pump, the pump is 'hidden' beneath the motor support floor (reinforced concrete) and what has been proposed by others is that a separate mobile crane is lowered into the basement for maintenance of each of the 9 pumps. But the mobile crane does seem very mobile as it is a large structure that has to be rated at 1.5 times the mass of the pump i.e. 6000 kg.
It must also be power driven.
It somehow seems a better idea to either remove the motor above and allow room for the pump below to be reached by the crane hook or that the motor is also on the pump floor with the pump having a horizontally orientated shaft rather than vertical. There would be no need for a floor above and the crane would have direct access.

Any thoughts on this I would be most grateful.

Regards
John

RE: Pump layout and mechanical handling

  1. There is a permanent bridge crane on the main floor
  2. The pump motor sits on the main floor
  3. The main floor supports the motor
  4. Openings in the main floor allows the pump and the motor to be connected by a shaft
  5. The pump sits directly underneath the pump motor in the floor below
Assume the pump and motor is already installed:

  • The motor is lifted off its anchor bolts by the main floor bridge crane
  • The shafts are then removed by the bridge crane. The crane lifting hook lifts the shafts one by one through the main floor opening where the motor used to permanently sit
  • The crane hook is dropped down the motor/drive shaft opening to lift the pump off its base so it clears the anchor bolts. The hook may attach to a framing assembly which has a number of lifting ropes or straps that actually distribute the weight of the pump. Talk to the pump manufacturer and ask them how they lift the pump off the delivery flatbed. You should also talk to a millwright about how they move heavy equipment around. You might be very suprised about their inginuity. Putting a crane down there is typically not necessary. After all you are not doing this everyday. Usually you only need access to the impellor
  • Millwrights have a temporary setup down below to manually transfer the weight of the suspended pump (or impellor) from total dependence on the bridge crane to a setup where they can move the pump (or impellor) to another opening location (usually done by pipes laid on the floor) where there is an access opening directly above on the main floor. The bridge crane can access the pump (or impellor) below and lift it up to the main floor. You have to make sure you have the height clearance to lift the pump (or impellor) and take into account all the lifting assemblies and lifting straps

RE: Pump layout and mechanical handling

(OP)
Many thank for your detailed response QualityTime.

The 5 points you simplify are correct. Only slight alteration in that the motor is not on a 'main floor' at present. The pump is on the floor and some kind of intermediate reinforced floor to support the motor is above it. Of course it only has a small hole in it for the shaft!!
this intermediate floor has had me question a few weeks ago that there is not enough mass in it. I'm not a civil engineer, but mechanically I have asked the motor supplier for full installation details and loading etc.

The bullet points you made reflect my thoughts exactly. I did a large pumping station recently and that is exactly how the pumps were removed. And as you stated, the pump casing remains in-situ and all the insides can be pulled up through the motor spigot location hole.
The pump motor was placed on a local 'stool' nearby allowing the motor to remain vertical.

This seems like standard procedure to me QualityTime. Will do. my best to have this looked at in more detail.

Many thanks again for excellent post.

Regards
John

RE: Pump layout and mechanical handling

Just to clarify, the pump internals are not pulled through the motor shaft openings...only the shaft:

  1. The upper pump casing is removed by use of the bridge crane and set to the side at the pump level.
  2. The bridge crane then lifts out the impellor and sits it on a manual assembly at the pump level.
  3. The bridge crane at this point is uncoupled from the impellor.
  4. The impellor is then usually manually moved to a location where there is a free and clear access opening up to the first floor.
  5. The bridge crane shackle is dropped to the pump level to hoist the impellor onto the first floor and moved to the loading bay.
Sometimes, when they cannot fit the overhead bridge crane shackle through the motor shaft opening they attach cloth sling belts to the shackle and thread it through the shaft opening. Or somtimes they attach a smaller shackle to the bigger shackle so that the smaller shackle goes through the opening. Just make sure the motor shaft opening in the floor is of ample size.

RE: Pump layout and mechanical handling

(OP)
I understand QualityTime....

It just so happenned at the Liverpool Wastewater treatment works Puming station, we could pull all the internals up through the steel plate which was supporting the 500 kw motor.

But this current project is a different arrangement and pump.

Will check the size and mass of the impeller etc and propose an alternative (if viable).

Thanks again.

RE: Pump layout and mechanical handling

One issue that you may have with the system you described is that it is very important that all parts of the motor are accessible.

RE: Pump layout and mechanical handling

(OP)
Sure!!
Its 2.6m high plus we have 50mm cooling water supply piping....

RE: Pump layout and mechanical handling

Are these water cooled motors

RE: Pump layout and mechanical handling

(OP)
Yes.... WEG 1800 to 2200 kW

RE: Pump layout and mechanical handling

I am not a fan of water cooled motors. Having water so close to electricity does not appeal to me. But it is done. I have seen cases where there has been leaking

RE: Pump layout and mechanical handling

I do not know the exact layout and orientation of the pump. You should check with the pump manufacturer if it is advisable to orient your pump this way. Show them what you are doing. Let them comment. Problems with weight on bearings, seals etc

RE: Pump layout and mechanical handling

QT,are you including the millions of electric submersible pumps in your evaluation of disliking this pump build?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Pump layout and mechanical handling

Artisi, the only thing I am saying is to double check with the pump manufacturer that they can get a pump cast and oriented that way. What are the pros and cons? This is a big pump. Lots of money on the line. Discussing things with people creates a learning atmosphere. Best of all is that it costs nothing to ask. I would assume they have already done this if they have gone this far and have layouts done but it does not hurt to go through the exercise. Remember you and I know a lot of things about pumps and it was gained through a lifetime of experience when the internet was not around. Most likely our experience was gained because we took interest and asked questions. The best way for JohnWeal to learn is for JohnWeal to ask the pump manufacturer everything that comes to his mind...no matter how trivial the question is. It is just a phone call. JohnWeal always make sure you talk to a technical guy at the pump factory smile and not a salesman

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