Suction strainer pluggage design upgrade ideas 1

[mjpetrag]

I have 2 pumps (one back up) that regularly fail seals due to the strainers on the suction side plugging up every month or two. There is a strainer for each suction pipe to each pump that can be swung for cleaning on the running pump. I wanted to hear design ideas for how to fix this problem.

Things we have looked at are dP alarms across the strainers to send to the control board for operators to swing and clean the suction strainers.

We've also looked at installing low amp shut downs, but have had problems in the past with the pump shutting down during deadhead conditions. I think we can fix this with a minimum flow bypass on the discharge.

Are there any other ways to fix this problem without significant modification? What is the most successful way in your opinion?

-Mike

 

[BigInch]

REGULAR CLEANING!!!!!!!

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[mjpetrag]

It's one of those things we have to idiot proof unfortunately...

-Mike

 

[vpl]

To back up what BigInch said:

If you don't have an automated cleaning system for your strainers, then create a "preventive maintenance" program. If the pumps are failing "every month or two", then schedule a cleaning every three weeks. If three weeks turns out to be too short a time (i.e., the strainers are clean when inspected and backflushed), then increase the cleaning intervals. When you get to a failure point, back your intervals back down by a week.

If your source of fluid is fresh/sea water, realize that there are annual cycles of plant and animal growth that may effect your screens. If you are affected by such growth, there may be times when you're cleaning the screens daily -- or even continuously!

P.S., dP instruments are a good idea.

Patricia Lougheed

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[ione]

A flow switch on the suction side alerting when flow is dropping below a set threshold could be an alternative.

 

[ash9144]

DP reading/alarms, then swap pumps and clean the strainer. This shouldn't be a major undertaking for an operator to do. So if there is a lot of complaining about it then your ops are very spoiled.

You also mention "trouble when dead heading"...thats none too good for your seals either.

 

[BigInch]

It is totally rediculous to not expect to clean the strainer once a month. The design is probably pretty much already idiot proof; add the alarms if you want to be totally sure, but also realize that you're really trying to design for lazy, idiots and that is impossible, meaning that if it's not the strainer, it will just be something else. Get them off their lazy cans by telling them it will be coming out of their paycheques if it fails again.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[mjpetrag]

I agree, but I've seen a strainer go a month with minimum dP across it. I've also seen a strainer go bad in a day due to a process upset.

I want to put something in place just in case it doesn't get caught between rounds. It sounds like dP instruments are the way to go. I have spoken to management about the issue for the past few weeks about more oversight, so at least the ball is rolling on that.

This is turning more into a social experiment than engineering


-Mike

 

[rmw]

If the strainer isn't a duplex strainer, it should be. With the proper DP indicating instrumentation, the baskets can be switched and the strainer cleaned immediately.

rmw

 

[1gibson]

Motorized, self cleaning strainers do exist. Here is one of the first results from google:

http://www.process-controls.com/John_Brooks_Company/filters_self_cleaning_strainers.htm

I would be frightened to check on prices, but I'd also find constant seal repair costs hard to swallow.

 

[bimr]

Go back to the process engineer that designed this system and have them install the correct equipment to remove the solids before it gets to the pump.

Strainers should be used to protect the pump during process startup and then removed.

 

[BigInch]

bimr, theoretically I'd have to say you are right, but whoever wrote that did't work very much with crude or pipelines. Being that the OP says they only clog up once every month or two, I also suspect he is not working with pipelines or crude, so you make a very good point.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[racookpe1978]

Add a duplex strainer, with a rotary (scraping) type screen strainer upstream of the pump suction duplex strainer.

I agree - and want to reinforce the above recommendation to get rid of the garbage (automatically!) BEFORE you start using the pump strainer as your final protection.