×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Reliability of oil mist lubrication

Reliability of oil mist lubrication

Reliability of oil mist lubrication

(OP)
We encounter a dangerous fire in our refinery recently.

The direct cause is the failure of the pump mechanical seal which cause the crude oil to leak.

After the fire, when we check the bearing, we find that pump bearing(ball type) also is damaged.

The bearing balls are no loner spherical and some balls disappear.

We use oil mist lubrication for all the rotating machine in our refinery.

What could be the root cause of the fire?

Oil mist fail -> Bearing fail -> Mechanical Seal fail ?




RE: Reliability of oil mist lubrication

Are you asking "is my proposed failure sequence a possible one" ? If so - answer is apparently yes.
If you are asking what the actual cause was, its obviously impossible to say without an on site investigation, which will no doubt occur and probably involve insurance investigators, legal experts etc.
If you suspect the oil mist system - there are many possible things that can go wrong, as simple as such systems are, such as :

1. Tank ran dry
2. Loss of air pressure
3. Clogged nozzle(s)
4. Pipe break
5. Poorly designed sytem leading to puddling

etc etc

You haven't indicated whether you know why the oil ignited.
I won't make any other posts on this topic.

RE: Reliability of oil mist lubrication

If the oil mist failed, the bearing would heat up enough to ignitet he remaining lubricant and start the fire. It happens more often than you think!

Lester Milton
NBC Group Ltd, Telford, Shropshire, UK

RE: Reliability of oil mist lubrication

Hippo41
I know I said I wouldn't be replying to this post again - but just this once - I've seen an awful lot of marginally lubricated bearings that have got red hot and burnt up, (probably hundreds) mostly in the machine tool field - mist lube and oil air - and never once have I seen that lead to a fire - there just wasn't enough oil around for that. But I humbly bow to you superior experience!

RE: Reliability of oil mist lubrication

There are in excess of 20,000 pumps in USA refineries that are lubricated with pure oil mist (this does not count pumps in other businesses or in other countries).  There is no know case in which oil mist has caused a fire.  

RE: Reliability of oil mist lubrication

What is the principle by which fire is avoided in presence of oxygen, heat, and oil mist?

RE: Reliability of oil mist lubrication

Oil mist is one part oil and 200,000 parts air.  That is far below the lean limits of flammability.  Concentrations of 1::250 is required to support combustion.

RE: Reliability of oil mist lubrication

(OP)
The fire is caused by the hot crude oil (140 C) leaking  from the damaged mechanical seal, not the oil mist itself.

What I am saying is that poor oil mist distribution may cause failure of pump bearing which then induce a seal failure, and let crude oil leak to the air.

It is surely very easy to make a big fire when hot crude oil contact with air.

RE: Reliability of oil mist lubrication

Texaco - thx, that makes sense now.

ponderer- is there any other equipment fed by same oil mist system?  (if so then one would think the other machines would have been affected by system failure as well).

RE: Reliability of oil mist lubrication

(OP)
All the process pumps in this refinery are serviced by the centralized oil mist system.

RE: Reliability of oil mist lubrication

No matter what the lubrication mode, bearings will eventually fail from fatigue.  Having said that, there is one refinery in the NW that uses oil mist and claims a MTBR of 10-11 years.  I don't think that this recored is possible without oil mist lubrication.  

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources