Failure of Mechanical Seals
Failure of Mechanical Seals
(OP)
I am a student doing internship in a chemical industry
One of the major problems they are facing is the failure
of the mechanial seals.My assignment is to improve
the design of mechanical seal.or bring some
good changes.
Therefore i need information inthis regard
One of the major problems they are facing is the failure
of the mechanial seals.My assignment is to improve
the design of mechanical seal.or bring some
good changes.
Therefore i need information inthis regard





RE: Failure of Mechanical Seals
What form does the seal take? Ball? Poppet? O-Ring?
What are the seal materials?
What is the working fluid?
What are the working pressures?
How is a failure defined?
RE: Failure of Mechanical Seals
Investigate easy failure causes/solutions 1st and eliminate and progress to the more difficult:
1. Seal type correct for service? Use KISS principle...Single mechanical, double, tandem, etc.
2. Check fluid pressures...a stuffing box P w/ pump discharge blocked > sealing fluid P will wreck havic & cause a seal to "fail" (leak). As djk mentioned, define what is called a failure.
3. Check MOC of stationary and rotating faces & compared to
what the process fluid is...
4. Temperatures of process fluids OK for seal?
5. Solids present in seal flush fluid?
....
Hope this helps and gets you off on a good start...
RE: Failure of Mechanical Seals
RE: Failure of Mechanical Seals
- What is the type of arrangement
- Static sealing ?
- Dynamic Sealing - Rotary, Reciprocating ?
- What is the process fluid ?
- What are the present sealing arrangement and materials
involved ?
- What pressures and temperatures are involved ?
- Study closely the Clearances between the shaft and
housing. Higher pressures would mean lesser clearances
to avoid any extrusion and blow out.
After you collect these details and have your info ready speak to some good seal vendors - some of the pioneers in this area whom i came across are Parker, Green Tweed, EGC and many others are also there. You can refer their catalogs and speak to them. Most of them have their websites just search in the engines. One good book i came across was 'Seals and Sealing Handbook' by R H Warring. i hope you would find this information useful.
RE: Failure of Mechanical Seals
Tom Worthington
pworthi@astro.as.utexas.edu
RE: Failure of Mechanical Seals
www.mcnallyinstitute.com
when i was starting out, there was tons of info here that brought me up to speed quickly.
RE: Failure of Mechanical Seals
Material compatability
Heat- including seal generated
API piping plans
Do the seals fail on start-up?
Stuffing box pressure
Operation-Does the equipment cavitate? NPSHA
RE: Failure of Mechanical Seals
- Correct material selection for the combination of rotating and stationary faces.
- Multi spring or single spring arrangement (depends on how dirty is the medium)
- Gasket material
- Shaft run out
- Vibration status
- Shock loading
- Solid impurities (scorring of faces)
- High temperature causing evaporation of film between faces and thus luck of lubrication.
- Thermal shocks
- Seal face surface fatigue
It is true you have a hand ful'upfuLL!!!
Good luck!
RE: Failure of Mechanical Seals
Check the installation instructions then watch the process to make sure it's happening right.
I'd also suggest the McNally Institute for information and even classes.
RE: Failure of Mechanical Seals
I would like to add that big name (burgmann, crane etc) mech seals are actually extremely reliable when not mis-applied into the wrong application or mistreated by turning off cooling water etc.
RE: Failure of Mechanical Seals
Unlike like stuffing boxes mechanical seals are very sensative to the product and pump specifications.
I would go to the original specifications of the pump and check what the specs. were for the seal when the pump was installed. Check to see if a more up to date seal is now available. Also check if the capacity of the pump has changed (during a turnaround) and if the seal specs have been updated to match.
Also study the manuals of the seals used on the plant and then sit down with the chief mechanical fitter(not the engineer) and let him explain the problems to you.
RE: Failure of Mechanical Seals
As mentioned above, get the seal vendor involved. You might be able to build a better mousetrap, but there's going to be a lot more mice by the time you get done.
Keep the wheels on the ground
Bob
showshine@aol.com
RE: Failure of Mechanical Seals