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9-Granite

## How to Prepare Logarithmic graph as per the attachment

How to prepare the graph as per the attachment

Regards,

Robert

14 REPLIES 14
23-Emerald III
(To:ranto)

Like this?

Success!
Luc

9-Granite
(To:LucMeekes)

I don't know how to take the valve fro the graph for our further calculation.

refer the attached calculation.

23-Emerald I
(To:ranto)

Your graph is describing a relationship for multiple variables (a/R and R/t.)  What article or text are you extracting this from?

9-Granite
(To:Fred_Kohlhepp)

API 650 Annex-P - External Nozzle load analysis

23-Emerald I
(To:ranto)

Okay.  Sorry, it took a while to locate a readable version of your document.

There doesn't appear to be any equation that develops these graphs which was what I was hoping for because that's what Mathcad does best.  So we're stuck having to "brute force" this.  I used WebPlotDigitizer(TM) to pick end points from the three lines in your plot.  (I may not have been terribly accurate.)  The attached file shows those values and recreates the plot in Mathcad (Prime 6.0).

Since the graph is a log-log, I suggest you do linear interpolation of the logs, I put in one equation (for a/R = 0.04), my Express won't run linterp, but you should get the correct value in full Prime.

It's not pretty, but it's one way.  This would give you three points on a S vs a/R plot so you could interpolate that curve (suggest polyfit?)

Good luck

23-Emerald III
(To:Fred_Kohlhepp)

Here is Fred's file in Prime 3.1

Success!

Luc

23-Emerald I
(To:LucMeekes)

Luc, thanks for the conversion!

I went ahead and taught Express to finish the job.  Attached is 6.0 file and pdf.

23-Emerald III
(To:Fred_Kohlhepp)

Attached the Prime3.1 conversion.

Luc

9-Granite
(To:LucMeekes)

Hi,

Thank you for your immediate help.

9-Granite
(To:Fred_Kohlhepp)

Thank you for immediate help.

9-Granite
(To:Fred_Kohlhepp)

Hi,

How to arrive the below mentioned values from the graph

23-Emerald I
(To:ranto)

There are a number of digitizing programs available on the web.  For this I used WebPlotDigitizer (a Google search should find it.)  Before computers and images on the screen we used to use our eyes and read the numbers from the graph.

Please note that FWK_2_logplot is WRONG; the vector of a_R has it's values inverted from what they should be.  Attached is FWK_2a_logplot  that has had that corrected and the presentation cleaned up and neatened,

23-Emerald III
(To:Fred_Kohlhepp)

And... converted to Prime3.1

9-Granite
(To:LucMeekes)

Thanks boss

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