On line Strainers, failure of mesh 1

[Iyer S]

We have an online strainer element (basket type), horizontally installed, Dry Gas at inlet.
We are experiencing frequent failure of the Mesh (80 Mesh, SS 347).

Pressure drop across the strainer is satisfactory
Open Area calculation for the mesh, with respect to cross sectional area of pipe is also satisfactory.

in such a scenario What all could be the probable causes of failures?

 

[3DDave]

What sort of failure? Fracture, corrosion, other?

 

[Iyer S]

Failure observed can be termed as Fracture....Mesh Elements broken at many many locations....apparently doesn't seems to be corrosion

 

[MFJewell]

Any piping work done recently that may have resulted in a large piece of debris being left inside the piping?

 

[Iyer S]

Jewell, Certainly not...no piping work have been done recently.
We repair the strainer, by installing / replacing the 100% fresh Mesh...but again within a month again the failure happens..

 

[LittleInch]

Excess velocity / poor structural strength of the basket??

I.e. is it simply supported at the top and the basket can vibrate / set up a natural frequency?

Some details of the filter and pictures of the damage would help a lot....

I'm a little confused by your terminology "On line" and "horizontal". Do you mean a top hat or witches hat between flanges filter??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[chicopee]

Are the strainer mesh made in China?.

 

[rb1957]

vibration ? it sounds like there isn't any significant load from normal operations, not enough to fracture the SS mesh.

constant airflow ? or oscillating, pulsing ??

another day in paradise, or is paradise one day closer ?

 

[dgallup]

What is the gas velocity? Anything close to sonic? Sounds like a vibration/fatigue failure to me. Pictures would be very helpful. I've found nylon mesh to frequently be more durable if the temperature and media are appropriate.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[IRstuff]

gas temperature?

what is the strainer supposed to catch? are what the strainer is supposed to catch able to cause such damage?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[Iyer S]

Gentlemen...All the process conditions across the strainers were found satisfactory. No vibration or sonic velocity issues.
Its Dry Gas which is passing through the strainer. The Mesh Element is secured to the Perforated Plate. The Assembly fixed with RTJ Flanges.
Enclosed is the details of the strainer.

We are looking for any abnormalities at the upstream of the strainer...this is in progress.

 

[LittleInch]

Ok, that's a bit more info - a modified witches hat filter.

Leaving aside the eternal argument about which way around you should point these things ( I go for inside to out, but hey) are these new / newly installed?

Has anything changed from before?

What sort of actual velocity are we looking at here?

Other than some sort of swirl meaning that flow is being sent predominantly into one part of the screen, what is the open area of the internal support screen / punched plate?

Are the holes in the punched plate smooth or jagged?

Can you attach a photo including a close up?


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Jboggs]

I'm really kind of surprised that there are this many posts on this question without (except for a question about China) a single mention yet of going back to the manufacturer and asking for their help. Did you do that? What did they say? They are the experts. They want their product to succeed. They have seen many other similar applications. Plus if they are a reputable company they will have a staff of application engineers whose only job is to assist customers in the proper use of their products. Why do so many of today's engineers need to be reminded of that resource? That's always been my very first call.

 

[rb1957]

so that looks like you have a 750" (?) OD, and a 540" (D2) plate ?? and a 3 bar pressure drop and flow is putting the mesh in compression.

is D2 a solid plate ? (doesn't look like mesh)

putting the mesh in compression doesn't sound like a good idea.

has this failure started recently ?

have you done a flow study around this strainer ? maybe there's some instability in the flow field ??

another day in paradise, or is paradise one day closer ?

 

[LittleInch]

rb - I'm pretty sure you'll find those dims are mm....

D2 is the inside hole - flow is right to left (outside to in)

The 3 bar differential is rather high - iyers - what differential do you think is OK?? - "Pressure drop across the strainer is satisfactory"

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[rb1957]

ok a 30" pipe is still big (to me).

if D2 is an open hole ... not much of a strainer ? if it's that open, why the pressure drop/rise ?

it'd be better to have the mesh in tension, no?

another day in paradise, or is paradise one day closer ?

 

[LittleInch]

Looking at a few other sites, 3 bar differential for the mesh looks very high - many state 0.5 bar.

I prefer inside to out with mesh on the inside, but many other swear by the opposite.

The thing is these are only supposed to be for initial commissioning and cleaning, not a long term use, so some unanswered questions.

Actually Iyers - you are actually flowing this thing from outside to inside are you??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[lilliput1]

Flow should be inside out so screen will be in tension instead of compression. This looks like a temporary strainer. Standard wye strainers have provision for blow off valve. Standard basket type strainers have removable top.

 

[Tmoose]

14 posts and 6 days later, pictures of the failed strainers would sure be helpful.