how bolt length (DIN) is calculated?

[nuwul]

Hi. I still don't understand how the bolt length is calculated in P3D. Can anyone explain?
I didn't set any bolt mapping, just adding bolt length & flange thickness as shown in the attached image. in P3D when i connecting flange-flange the length value shown is = 70mm

however in spec catalog the value for bolt length = 60mm & flange thk = 15mm

so why i get bolt length = 70mm? 

[h_eger · Accepted solution]

@nuwul ,

Enclosed is the calculation by Studt bolts via PET

if the length exceeds 65mm, it is automatically rounded up to 70mm

[nuwul]

i see. then what is the function of the bolt Length since it has its own calculation?

what if i'm adding the check valve, will it just added the valve length? or for this one have different calculation. 

[Michiel.Valcke · Accepted solution]

Bolt length in Plant is calculated as such:

Take the default Bolt length for its respective size and subtract the preconfigured flange thickness twice.
Bolt Length - 2x Flange Thickness

Then look at the Flange Thickness value of the actual flanges used in the connection and add those.
Bolt Length - 2x Flange Thickness + Flange Thickness Flange1 + Flange Thickness Flange2

Then look at the Bolt compatible standard. If it has the same name as a bolt mapping table, we round up our value to the nearest value from the table (for the used bolt size). If there is no specific bolt table with the same name as the bolt compatible standard, the default table is used. Which rounds up to 1/4 inch by default (in ASME), or 5 or 10 mm (in DIN).

Note that the default DIN catalog and the DIN EN catalog that is available in the app store do not have any flange thicknesses filled in. So basically you will take the bolt length - 2*0 +0 +0. If you start filling in flange thicknesses for the flanges in a catalog based on DIN or DIN EN you will also need to fill in flange thicknesses in the bolts that you're using, otherwise your bolt lengths will make little sense.

[nuwul]

hi @h_eger, 
where can i get this PET calculation?

[h_eger]

https://www.auxalia.com/en/software/plantexpresstools/

Bolt Calculation

[nuwul]

hi @Michiel.Valcke  

done my calculation but it looks like this formula Bolt Length - 2x Flange Thickness + Flange Thickness Flange1 + Flange Thickness Flange2 only the bolt mapping follows default bolt mapping.

Any ways to get the exact length?

if the connection is flange-gasket-flange, why the gasket not been calculated?

for size 1" with bolt length=69mm, bolt flange thk & flange thk=16, the bolt total length = 69mm

then tested with wafer check valve: 
Bolt Length - 2x Flange Thickness + Flange Thickness Flange1 + Flange Thickness Flange2 + valve length

69 - (2x16) + (16+16) + 22 = 91

but here in P3D i get bolt length = 93

so where is this 2mm coming from?

in spec catalog, the bolt is includes with hex, washer & nut. is this calculation include this this items too?

[Michiel.Valcke]

the gasket, washer & nut do not take part in this calculation, you compensate for that by using a smaller or larger initial bolt length value. If you find that your gasket, nuts and washers are thicker and thus your bolts are just too short, change the initial bolt length.

concerning the extra 2 mm did you check your compatible bolt standard, is it possible the value is rounded up there?