Factors in NC-3658.3

[iTools]

I need to do some verification of flanges according to NC-3658.3 but I am a bit confused about the constants used in the expressions.

Now, the ASME-III, Division 1, section NC states the following in eq. (12):

Mfx < 21437.5 *(Sy/246960)*C*Ab (SI version)

Could anyone tell me what this factor of 21437.5 is? And what units does it have?

Kind regards

Hans

 

[BJI]

Not sure if you are working with an older version but it looks like your units are in kPa. The current version of equation 12 in SI units is Mfs <= 21.7(Sy/250)*C*Ab, which is working in MPa (N/mm²) and mm, so you get a moment in terms of Nmm. The constant is your bolt allowable strength divided by 8 and is in units of MPa. The yield strength ratio in parenthesis is unitless.

 

[MBlackman]

Calculator with auto-lookup of data here, in case it helps

https://stressandintegrity.com/app/index.lc/ASMEIII

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