Bend SIF Scratchpad - CAESAR II - Help

Piping Input menu: Environment > Review SIFs at Bend Nodes

Input Tools toolbar: Bend SIF Scratchpad

Allows you to calculate and review stress intensification factors (SIFs) for a bend at the selected node.

Displays the Node Selection dialog, and then the appropriate bend SIFs dialog.

Node Selection Dialog

Controls options for selecting the node.

Enter bend Node Number to be reviewed

Specifies the bend node number where you want to evaluate the stress intensification factors.

OK

Displays the B31J - Review Bend SIFs dialog for all codes except IGE/TD/12 or the Review Bend SIFs for IGE/TD/12.

Both dialogs display the same fields but perform different calculations.

B31J - Review Bend SIFs Dialog (or Review Bend SIFs Dialog)

Controls options for reviewing bend SIFs.

Node

Displays the node number.

Bend Radius

Displays the bend radius. CAESAR II assumes a long radius by default. You can override this value or select a value from the list.

Typical units (depending on your unit system):

• in

• mm

• cm

Long

Indicates a long radius bend. The radius is equal to 1.5 times the nominal diameter.

Short

Indicates a short radius bend. The radius is equal to the nominal pipe diameter.

3D

Indicates a 3D bend. The radius is equal to 3 times the nominal diameter.

5D

Indicates a 5D bend. The radius is equal to 5 times the nominal diameter.

Bend Type

Specifies the bend type.

For most codes, this refers to the number of attached flanges: 1 - Single Flange and 2 - Double Flange. A bend should be considered flanged if there is any heavy or rigid body within two diameters of the bend that significantly restricts the bends ability to ovalize. If there are no flanges on the bend, then do not specify a value for Type.

For BS 7159 or UKOOA codes with fiberglass reinforced plastic (FRP) pipe, this entry refers to the material laminate type. The laminate type affects the calculation of flexibility factors and stress intensification factors.

1 - CSM (Chopped Strand Mat)

All chopped strand mat (CSM) constructing with internal and external surface tissue reinforced layer.

2 - VM & Woven Roving

Chopped strand mat (CSM) and woven roving (WR) construction with internal and external surface tissue reinforced layer.

3 - CSM & Multi-Filament

Chopped strand mat (CSM) and multi-filament roving construction with internal and external surface tissue reinforced layer.

For ISO 14692 2005, only 3 - CSM & Multi-Filament displays.

For ISO 14692 2017, only 1 - Hand Lay displays. For more information, see Hand Lay.

Bend Angle

Displays the bend angle.

Fitting Thickness

Specifies the thickness of the bend if that thickness is different than the thickness of the matching pipe. If the thickness is greater than the matching pipe wall thickness, then the inside diameter of the bend is smaller than the inside diameter of the matching pipe.

Typical units (depending on your unit system):

• in

• mm

• cm

CAESAR II calculates section modulus for stress computations based on the properties of the matching pipe as defined by the codes.

The pipe thickness is used twice when calculating SIFs and flexibility factors; once as Tn, and once when determining the mean cross-sectional radius of the pipe in the equation for the flexibility characteristic (h):

h = (Tn)(R) / (r2)

Tn = Thickness of bend or fitting

R = Bend radius

r = Mean cross-sectional radius of matching pipe

= (OD - WT) / 2

OD = Outside Diameter of matching pipe

WT = Wall Thickness of matching pipe

Most codes use the actual thickness of the fitting (this entry) for Tn, and the wall thickness of the matching pipe for the calculation of the mean cross-sectional radius of the pipe (the WT value). More specifically, the individual codes use the two wall thicknesses as follows:

The bend fitting thickness (FTG) is always used as the pipe thickness in the stiffness matrix calculations. However, the thickness of the matching pipe (WT) is always used in the bend stress calculations.

Number of Miter Cuts

Specifies the number of cuts in the bend if it is mitered. The software checks if the value creates cuts that are closely or widely spaced. If the bend is determined to be widely spaced, and the number of miter cuts is greater than one, the bend should be broken down into “n” single cut widely spaced miters, where “n” is the total number of cuts in the bend. The number of cuts and the radius of the bend are all that is required to calculate the SIFs and flexibilities for the bend as defined in the B31 codes. The bend radius and the bend miter spacing are related by the following equations:

Closely Spaced Miters

R = S / (2 tan θ )

q = Bend Angle / (2 n) where n = number of miter cuts

Widely Spaced Miters

R = r2 (1.0 + cot q) / 2.0

r2 = (ri + ro) / 2.0

θ = Bend Angle / 2.0

Seam Weld

Indicates that the bend is seam welded.

B31.3

If the B31.3 piping code is active, the Seam Welded check box is used to activate the Wl box for bends. The Wl box is the weld strength reduction factor used to determine the minimum wall thickness of the bend element.

B31.3 Chapter IX

Not used.

IGE/TD/12

Used by IGE/TD/12 to calculate the stress intensification factors due to seam welded elbow fabrication as opposed to extruded elbow fabrication. This option is only available when IGE/TD/12 is active.

Matching Pipe OD

Specifies the outside diameter of the matching pipe. This is used in the average cross-sectional radius calculation:

r2 = (OD - WT) / 2

OD = Outside Diameter as entered

WT = Wall Thickness of attached pipe

The B31.3 (1993) code defines r2 as the mean radius of matching pipe.

Matching Pipe Thk

Specifies the match pipe wall thickness. You should not subtract any corrosion. All SIF calculations are made ignoring corrosion. This wall thickness is used in the mean radius (r2) calculation as defined in the piping codes.

Elastic Modulus

Specifies the elastic modulus among EC, E1 to E9. This value is used for the pressure stiffening calculations.

Pressure

Specifies the pressures. Select PMax, P1 to P9, PHydro and none. This value is used for the pressure stiffening calculations.

Bend In-Plane SIF

Displays the SIF under in-plane bending.

Bend Out-of-Plane SIF

Displays the SIF under out-of-plane bending.

In-Plane Flexibility Factor

Displays the flexibility factor under in-plane bending.

Out-of-Plane Flexibility Factor

Displays the flexibility factor under out-of-plane bending.

Pressure Stress Multiplier

Displays the factor by which to increase pressure stresses for a mitered bend. This option only displays for the ISO-14692 2005 code.

Flexibility Characteristic

Displays the pipe factor.

Recalculate

Recalculates and displays SIFs, flexibilities, stiffnesses, and other related results after you change the input data. If you change the input data, CAESAR II allows you to transfer the data back to the model.