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Thickness of Perforated Sheet Design

04/26/2016 1:53 AM

Somebody Please explain me how to find the thickness of perforated sheet (filter) which is used in strainers. And also the "Collapsible pressure" of the perforated sheet?

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#1

Re: Thickness of Perforated sheet design

04/26/2016 2:05 AM

What do you mean by "find"?

Usually there should be a data sheet for your filter. Start by looking there.

Other than that you might want to utilize your engineering handbook to calculate collapse pressure.

Thickness can be measured otherwise.

Educate us and give us more context for your question.

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#2

Re: Thickness of Perforated sheet design

04/26/2016 3:16 AM

Dismantle the strainer, strip out the perforated sheet, and use a set of measuring callipers.

Collapse pressure is determined by using a theoretical section of the mesh material, and applying a stress analysis to it based on the pressure difference and the properties of the material on the assumption that it has no holes. Then one makes a correction factor to allow for the fact that it does have holes. However, if it is close to collapse in real life then there is a maintenance activity that is not being carried out, which is its periodic removal and cleaning of the mesh; it is a strainer - it is designed to block - that is its job.

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#7
In reply to #2

Re: Thickness of Perforated sheet design

04/26/2016 5:05 AM

Dear PW slack,

My question is to calculate the thk of the perforated sheet I regret for the inconvenience.

With regarding to the collapsible pressure Your answer seems identical to my previous researches about this topic. I used the Equivalent solid material concept to find the factor which is to be multiplied by allowable stress values of the material. Then to find the thickness of the material I implemented those values in ASME Sec VIII Div I thickness calculation formula. Since the allowable stress values for the material decreases the thk of the perforated sheet increased more than the filter catridge's (Strainer's) but the filter what we are getting is of very less thk and working good. Now My questions are the following:

1. Whether the method I used to calculate the thk from ASME SEC VIII Div I is correct or not?

2. whether the Thk of the material and collapsible pressure are inter related?

3. If so what is that?

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#8
In reply to #7

Re: Thickness of Perforated sheet design

04/26/2016 5:14 AM

A1) Declined.

A2) Yes.

A3) Ask the original equipment manufacturer.

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#9
In reply to #8

Re: Thickness of Perforated sheet design

04/26/2016 5:19 AM

I asked several OEMs & nobody answered. If anybody knows the relation please provide.

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#10
In reply to #9

Re: Thickness of Perforated sheet design

04/26/2016 5:35 AM

Installing equipment backwards so that there is a risk of collapse is always abstruse. Strainers work best when the flow is from inside to outside so that the basket never collapses.

Is this an attempt to re-engineer a strainer so as to provide a competing product?

  • If so, then that would explain the lack of response from original equipment manufacturers - protecting market share - and the reason for withholding that snippet from the original thread is abstruse.
  • If not, then given that the original equipment manufacturer has warranted a pressure rating for the equipment, the reason for the enquiry is abstruse.

Is this an attempt to re-purpose a strainer so that it does something else?

  • If so, then a stress analysis on the non-perforated element with a correction factor for the perforation is one way to go. Alternatively one could carry out practical testing.
  • If not, then the reason for the enquiry is abstruse.

Is this for some other purpose?

  • Then the reason for the thread is abstruse.

If there is some reason for withholding the purpose of the thread from the original thread then the reason for so doing is abstruse.

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#11
In reply to #10

Re: Thickness of Perforated sheet design

04/26/2016 5:46 AM

I never stated that my attempt here is to re-engineer the strainers and it is completely a knowledge based question. We require strainers along with our product and each and every time we asked for the collapsible pressure they are ending up with illogical answers.

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#12
In reply to #11

Re: Thickness of Perforated sheet design

04/26/2016 5:51 AM

That's because it is an illogical question, Dude.

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#13
In reply to #11

Re: Thickness of Perforated sheet design

04/26/2016 9:46 AM

Run a test. Find the pressure required to collapse a filter and divide that number by the area of the filter.

Sounds like you are asking the wrong question for the wrong reasons.

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#15
In reply to #13

Re: Thickness of Perforated sheet design

05/08/2016 3:41 PM

I do not understand the basics of your suggestions: if he knows the collapsing pressure (which is a difference in fact) why should it be divided by the filter area ? I would understand the operation if the measured value would have been a force but a pressure difference / area what meaning does it have ?

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#3

Re: Thickness of Perforated sheet design

04/26/2016 3:42 AM

You might consider reversing the flow from inward to outward; the basket will resist tensile stress much better than compressive.

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#4
In reply to #3

Re: Thickness of Perforated sheet design

04/26/2016 4:28 AM

Due consideration needs to be given to the consequent destination of the strained material.

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#5

Re: Thickness of Perforated sheet design

04/26/2016 4:36 AM

Sorry!!! the question is how to calculate the thickness of the perforated. i should have asked the question like this...

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#6
In reply to #5

Re: Thickness of Perforated sheet design

04/26/2016 5:03 AM

The equipment has a pressure rating that is determined by the manufacturer. So the manufacturer warrants that the strainer will not collapse with full pressure one side of the blocked strainer and it being open the other.

Were the pressure to increase above this figure, then the body of the strainer is under risk of failure, therefore the rating of the perforated element is irrelevant.

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#14
In reply to #5

Re: Thickness of Perforated sheet design

05/02/2016 11:31 PM

You measure thickness! Its generally the depth of your perforation!

I give you a ten out of ten for thickness.

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