Pump on Sliding Plates 2

[Chris0164]

Hi Guys,

I am working for an engineering company in Belgium (Europe) and just had a discussion with our stress engineer.

Piping has located an 1800 kg pump (operation temperature of 40 ° C - design 80 °C) 2 meters from a brick wall with the 8" suction lines penetrating the wall.

The wall is chemical and fire resistant and they plan to cast in the pipe, so they asked me to put the pump on Teflon sliding plates. Does that make sense ?? And if yes does anyone have a standard about this ?? (Pump Vendor did not have !!)

I already said that the expansion of the 8" pipe is neglect able and suggested to make the penetration more flexible
??

 

[UtilityLouie]

The expansion is negligible, but the problem comes around if you consider the wall and the pump suction perfectly rigid. A small growth in a small pipe that has no where to go creates incredible stresses.

I'm sorry I don't have a resource for you - but I have seen people "hot set" a pump. They put it on teflon slides warm up the system and then set the pump - but it's not on teflon slides the whole time. I have also seen pumps on a spring base - which allows the system to be flexible. That may be easier to find.

 

[plastx]

I can tell you that "Sliding Shoes" are used extensively in large pipelines like the Alaska Pipeline. At every support of the pipe there are PTFE (Teflon) or actually Rulon (filled PTFE)plates that allow for not only expansion/contraction but for extraordinary occurances like earthquakes, etc.

Sounds like overkill in your case but maybe there's some other reasons for it. If you still want to pursue go for a reinforced PTFE of some sort like glass or like Rulon. Virgin PTFE will creep under the pressure over time.

There's a Texas company that works with oil companies that sell these types of shoes.

http://www.sepbearings.com/index.html

Regards,
Mike

 

[MikeHalloran]

What happens to the pipe when the pump foundation settles?

What happens to the pump warranty when the pump is supported only by the suction flanges?

Who pays for rebuilding the wall when they need to replace the pipe?

The whole sliding plate / rigid plumbing thing makes no sense to me.

The pump vendor clearly has no standard because they never in their wildest dreams imagined that anyone would do such a thing.



Mike Halloran
Pembroke Pines, FL, USA

 

[JJPellin]

We have about 1400 centrifugal pumps in our plant. Four of these pumps are set on flexible mounts of the sort you are describing. Two of the pump have slide plates that are steel on steel with no teflon. There are studs from the foundation running through the pump mounting plate but they are double nutted with slight clearance to allow for sliding motion. The other two pumps are on spring mounts. All four of these pumps are very unreliable. All of them fall within our "bad actor" program. They have more problems with bearing failures, alignment changes and mechanical seal failures than typical installations grouted down to a full foundation. I don't care much for the ridgid pipe / flexible pump system.

 

[sprintcar]

Would it be better to use flexible pipe couplings or expansion joints - like the bellows design - that would allow suction pipe to change length without altering the location of your discharge pipe?

Moving the pump around can cause alignment changes, stressing in the bearing housing, as well as potential safety issues.

Plus, if you ever experienced a water hammer or other similar event, the unrestrained pump could become a projectile.

"If A equals success, then the formula is: A = X + Y + Z, X is work. Y is play. Z is keep your mouth shut."
-- by Albert Einstein

 

[NozzleTwister]

Back in the mid '80s I saw some pumps mounted on Lubrite slide plates in a refinery in New Jersey.

Although not the norm, it has been done by several engineering companies and the installations have performed successfully.

Depending on your pump and base plate, you may need build a separate frame (with slide plates) to mount the pump base plate to. If your pump base plate was intended to be grouted, you may still need to grout or otherwise stiffen the base. Finally you'll need to guide the frame so the pump assembly can only move axially to the suction nozzle.

I do recommend that you consider more traditional options before going the slide plate route. Your situation seems like an excellent place to use an elastomer expansion joint between the wall and the pump.

Good luck,


NozzleTwister
Houston, Texas