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bk_011-Visitor
1-Visitor
Feb 6, 2015 8:04 AM UTC
Solved

how to handle unit less numerical factor in equation

Hello all

i am using mathcad 15

while defining a variable, mathcad shows an error for a unit less numerical factor

Error

"This value has units:Unitless,but must have units:Length."

in the same way i have used unit less numerical factor it doesn't shows any error

i am confused , anyone please help me out

regards

Balaji

Fred_KohlheppAnswer
23-Emerald I
Feb 6, 2015 12:35 PM UTC

Balaji k wrote:

Thanks for your reply'

i tried this option also

but this is the standard template sheet , in that i have to use the formula what it was given in code book(Design standard)....

is there any other option to solve this issue....(with out mentioning the unit inside the formula)

Regards

Balaji

With respect to your "code book":

This looks like pipe stress calculation, also known as hoop stress. For a given stress (f) you're solving for what pressure you may have.

Hoop stress is simple: stress = (pressure)*(radius)/thickness, and orthogonal to it (pressure)*(radius)/(2*thickness)

d is pipe diameter?

e_rt is wall thickness?

So your d-2 should be d/2 to get the radius.

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8 replies

VladimirN24-Ruby IV
24-Ruby IV
Feb 6, 2015 8:09 AM UTC

Hi,

It would be better if you attach Mathcad worksheet, not a picture.

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bk_011-VisitorAuthor
1-Visitor
Feb 6, 2015 8:34 AM UTC

here i attached the file

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AndyWesterman12-Amethyst
12-Amethyst
Feb 6, 2015 9:01 AM UTC

looks like d.o has units of mm so you need to tell mathcad what the offset units are: m, mm, ft, in ...

Capture.PNG

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    bk_011-VisitorAuthor
    1-Visitor
    Feb 6, 2015 9:06 AM UTC

    Thanks for your reply'

    i tried this option also

    but this is the standard template sheet , in that i have to use the formula what it was given in code book(Design standard)....

    is there any other option to solve this issue....(with out mentioning the unit inside the formula)

    Regards

    Balaji

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    LucMeekes23-Emerald V
    23-Emerald V
    Feb 6, 2015 10:11 AM UTC

    I think there isn't. Well, work without units altogether, but I consider that NO option.

    If the "code book" is prescribing the formula as ".../[(do - 2) + ert]" it MUST (preferrably explicitly) define the unit of 2. If not, you can seriously question the "code book".

    success!

    Luc

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