Posted by: Lore80

## Finding allowables for particular objects - 07/04/17 09:51 AM

Hi to everybody, I am trying to develop the following problem:

Consider a flanged pipe limited by an anchor point on the opposite side. So the geometry is: Anchor point + more or less 1mt pipe + flange.

I was asking to me, what about allowable Forces and Moments acting on flange for a subject like this. What kind of rules have I follow?

First of all I am thincking that the subject of analysis is the union of pipe + flange, so the satisfation of the problem comes from the satisfation of piping allowable stress condition according to ASME B31.3 (is an example) and at the same time leakage ruling satisfation for flange itself.

Starting from this point of view I was asking to me if I have enought equations for obtaining Faxial, Resultant Shear Force, Resultant Bending, and Torque.

ASME B31.3 :

- Total Shear does not exceed 0.8 Sh, So maximum shear is at 0.8 Sh. Considering Z direction as axial, Resultant Shear is a function of Shear forces Fx and Fy but also shear involved by Torque. So one equation with two unknowns (Resultant Fx/Fy shear, and Shear from Torque, so Mt)

- Displacement Stress Limit Sa=Se is the maximum condition. This is a function of Resultant Bending and Torque, so two unknowns

FLANGE: Equivalent Pressure Design Criterium - Kellogg:

Pmax rating acc. to ASME B16.5 = P des + Pequivalent

P equivalent is a function of Faxial and Resultant Bending

So basically we have three equations with four unknnows.....is somewhere a fourth condition that I am not considering which can let me identify for example Axial Force?

Thanx to everybody for suggestings and opinions

Lorenzo

Consider a flanged pipe limited by an anchor point on the opposite side. So the geometry is: Anchor point + more or less 1mt pipe + flange.

I was asking to me, what about allowable Forces and Moments acting on flange for a subject like this. What kind of rules have I follow?

First of all I am thincking that the subject of analysis is the union of pipe + flange, so the satisfation of the problem comes from the satisfation of piping allowable stress condition according to ASME B31.3 (is an example) and at the same time leakage ruling satisfation for flange itself.

Starting from this point of view I was asking to me if I have enought equations for obtaining Faxial, Resultant Shear Force, Resultant Bending, and Torque.

ASME B31.3 :

- Total Shear does not exceed 0.8 Sh, So maximum shear is at 0.8 Sh. Considering Z direction as axial, Resultant Shear is a function of Shear forces Fx and Fy but also shear involved by Torque. So one equation with two unknowns (Resultant Fx/Fy shear, and Shear from Torque, so Mt)

- Displacement Stress Limit Sa=Se is the maximum condition. This is a function of Resultant Bending and Torque, so two unknowns

FLANGE: Equivalent Pressure Design Criterium - Kellogg:

Pmax rating acc. to ASME B16.5 = P des + Pequivalent

P equivalent is a function of Faxial and Resultant Bending

So basically we have three equations with four unknnows.....is somewhere a fourth condition that I am not considering which can let me identify for example Axial Force?

Thanx to everybody for suggestings and opinions

Lorenzo