ASME SECTION VIII, DIV 1, FIGURE UG-37.1 FORMULAS 1

[hhamza]

Does anyone know/have a source for deriving the formulas for area reinforcement?
Are the limits of reinforcement (UG-40(b) & UG-40(c)) calculations already taken into account in the formulas given?

thanks,

 

[SnTMan]

hhamza, 2nd question first, yes limits per UG-40 are incorporated.

1st question, these formulae are based on replacement of area removed to form the opening.
Formula for required area is a function of opening diameter and shell required thickness, additional terms compensate for difference in strength between nozzle material and shell material. These additional terms are unused in some configurations.

Areas available generally are based on excess material thickness within the limits of reinforcement, that is, the difference between thickness required and nominal thickness, less corrosion if applicable. Again, additional terms compensate for difference in strength between nozzle material and shell material, or reinforcing element.

That the UG-40 limits are incorporated can be observed by the formulae, i.e in A1 the terms "d" and "2(t + tn)" account for the UG-40(b) limits, in A2 the term "5t" or "5tn" accounts for the UG-40(c) limits. Keep in mind the calculations consider areas on both sides of the opening centerline. So, it's "5t" rather than "2 1/2 t", "d" is equivalent to "2d - d".

Additional area terms account for other configurations such as inward projection, re-pads, etc.

It is a simplified scheme developed when calculations were done by "hand", it served and continues to serve well.

Calculate 'em and add 'em up.

Regards,

Mike