Split case pump mechanical seal failure

[kebecano]

Hi everyone, I am currently having problems with mechanical seal failures on two Aurora Series 421 - Horizontal Multi Stage Split Case Pumps.

Sync speed of 3600RPM, ± 1000gpm

Size: 6x6 with an Impeller 11.315 trimmed down to 11.25in
by dealer in order to reduce amp draw


I would like to know how to proceed with troubleshooting this problem as there has been several seals that have blown (see attached pictures)

Is it possible to determine most likely cause from the pics or is there a standard pump seal failure checklist???

Thank you very much for the help.


I'll post more details as I get them.

http://files.engineering.com/getfil...2-4233-afc4-0b9b0cabaebd&file=Imagen_001X.jpg

http://files.engineering.com/getfil...5-425e-814a-c8d5b6ba1bcc&file=Imagen_002X.jpg

http://files.engineering.com/getfil...2-443a-a054-52901636a921&file=Imagen_003X.jpg

http://files.engineering.com/getfil...9-4a16-bfbb-23bfe282d599&file=Imagen_004X.jpg

http://files.engineering.com/getfil...6-4b97-9077-0d7f46b59de0&file=Imagen_005X.jpg

http://files.engineering.com/getfil...6-40fc-b0d5-2b646c6fc9de&file=Imagen_006X.jpg

 

[kebecano]

BTW pump only ran a few hours...

 

[kebecano]

Sorry, I have another question, any opinions from our resident pump experts as to pump quality from these two manufacturers??:

1. American Marsh Pumps
2. Aurora Pumps

thanks

 

[CH5OH]

for mechanical seal...i am missing some parts.
What's the liquid been pumped?
Operating temperature of liquid been pumped?

If the internal seals are damaged most likely cause
would be overheating of pump...
was the pump properly dearated and lined up ?
was the pump properly aligned with driver?

 

[kebecano]

Sorry about that, fluid pumped is infiltration water in a mine, temperature is around 70F.

I'm currently in the process of finding out if pump was correctly dearated and aligned prior to being put in service.

Assuming it has, what could blow out the seal like this?? I come from a hydraulics background and if I saw something similar to this I would have thought excessive case pressure, water being pumped above its vapor point thereby causing it to increase the pressure around the seal.

Some have mentioned seal quality and type of seal might be the cause.

What would the main difference be between a balanced and unbalanced type seal??

Thank you

 

[CH5OH]

well if you talk about a mine apllication, indeed vapour pressure could be the problem.
NPSHr should be a few feet below NPSHa
in other case pump could be severe cavitating and in extreme
overheating on internal seals (lack of flow)
it would be preferred for the pump to overcome height in its discharge line, rather than in the suction line.

 

[kebecano]

Were you able to see the pictures I attached?? What are your thoughts concerning them.

Thankyou for the information and help CH5OH , I appreciate the help!

 

[kebecano]

anyone else want to chime in on what the posted pics might lead to as the cause of failure??

 

[kebecano]

I should have more info as well as the pump curves late tonight

 

[Kailee]

Just a thought, but if we are trying to evaluate a seal failure, why are you posting pictures of the impellers?

Lets see the seal faces, sleeves etc. Maybe we could be of some help? their condition would be more telling than the outside of the impellers.

Cheers!

 

[kebecano]

Sorry, I just tried to put everything relevant to impeller and seal. I'm not very familiar with centrifugal pumps yet so I thought the pics of the impeller might give someone else a clue as to what had gone on.

I guess the only pic worthwhile would be the 4th one. That's what was left of the seal when the pump cover was taken off.

I have more of the story concerning these pumps. Originally the brand should have been American Marsh, but dealer sent Aurora series 421 instead due to we're not quite sure yet.

AM pump curves were around 347 hp for around 1000gpm whereas the Aurora pump was apparently between 350-400. Since existing motors are 350hp, dealer proceeded to shave 1/8th inch off the impellers, stating that it would now be adequate for 350hp motors.

I'm starting to think, maybe the impellers weren't correctly balanced afterwards which might have induced vibrations and eventually caused seal failure.

I'll try and post more info tomorrow, alignement will also be verified.

thanks

 

[JoeySoap]

When a seal fails so dramatically (picture 4) in such a short period of time I would think that the failure investigation should initially be around the seals possibly running dry. I can see that it is a Chesterton seal, I would have the installation and operation of the pump reviewed by one of their reps they're usually pretty helpful as long as you get one of their experienced guys. Not all of them have a lot of knowledge in my experience.

If you have trouble with making any sense out of what Chesterton say, then go to a competitor. I have always worked closely with and recommended John Crane seals, but others may not. HTH.

 

[kebecano]

thanks a lot, I'm currently looking into this

 

[CH5OH]

for 3 bronze sleeves, if they are seized and you dont want to sweat out delivery times, remove them by applying a torch on them,while keeping shaft submerged in water....
knock em off using wooden block.
slide sanding surfaces on shaft and sleeves, try to keep diametrical free play below or around 0,5mm.
the mechanical seal is easier to get by, I suppose...
align pump with motor,fully submerge pump before startup
and listen for cavitation (check NPSHA/NPSHR in pump data)

 

[Artisi]

Send the seals to the seal manufacturer, it might surprise you to know that they are pretty good at trouble shooting seal failures.
Without good pic. of the seals to show here you will end up with a vast amount of info that is irrelevent to your problem.

 

[flexibox]

there are a number of things to look at:
1 What are the face materials? If carbon vs Silicon or Tungsten carbide then the water may be dirty and wear takes place due to abrassives.
2 An unbalanced seal is limited to approx 150PSI depending on size whereby a balanced seal can handle much higher pressures. its difficult to determine which you have.
3 What is the operating pressure? Is the pump located underground? If so haw many levels down and what is the Pump suction/discharge pressures?
4 Where you at the pumps during start up? Were the valves open?
5 If you have dirty water then you should have hard faces; make sure that you have plan 11. looks like you can use the plugged connection in the gland plate.
6 you should include seal face photos to assist you with the trouble shooting.
7 I think that you may have had air entraped and seal overheated, looking at Pic 4 the gland plate gasket seems to be cooked? Or is this a silastic to seal the split case?
8 what do the orings in the seal look like?


trust this helps!

 

[Pumpone]

Hi, as your photos, you are using Chesterton 155 cartridge Mechanical Seal,

http://www.chesterton.com/ES/Products/Pages/Product.aspx?ProductLine=MSD&Category=Cartridge

Seals&ModelID=155&DocumentType=Product Brochure
Seal faces are missing in your picture so im asumming they destroyed one each other. There is no evidence of cavitation, dry run, so in those cases hot generate some marks in sleeve and shaft.
It apperars that your wear rings are made in bronze, so it very difficult for bronze to seize.
For making this fail so quickly the installation check list will be as follows:
-Mechanical seal setting (axial and centered) prior to star up the pump.
-Pins of collarin of mechanical seal will be tight.
-Put manovacuometer to see lost of suction pressure.
-Check submergence suction level to prevent air intake.