ASME B16.9 Elbow

This bend is produced without using of longitudinal welds like welding elbow. There's no difference in stress analysis of Forged elbow, Induction bend and Welding elbow in ASME and EN codes.

Central bend angle should not exceed 90 degrees (More...). START-PROF doesn't check the Wall thickness for this type of bend according to ASME code, but check it according to Russian codes.






Element name. If checked then it shown in 3D view


If you push this button, you will see h, SIF, k-factors for the bend

Radius, R

Bend average radius  (0.5D<R<10D). Long - 1.5DN, short - 1.0DN

Get properties from matching pipe

Get properties from matching pipe

Calculate weight automatically

If selected, reducer weight is calculated automatically as torus volume with wall thickness equal to that of adjoining pipes


Bend weight (with flanges) without insulation and product. Set according to standards without taking into account the overload factor. Product and insulation weight with corresponding overload factors are calculated automatically based on adjoining pipes

Longitudinal Weld Joint Efficiency Factor, E

Longitudinal weld joint efficiency factor, E. More...

Calculate angle automatically

The bend angle used in bend's flexibility factor (k-factor) calculation in some codes. The option "сalculate angle automatically" should be turned on by default.

It is recommended to turn off this option when the bend was splitted into several parts to model the support on bend. In this case the angle should be specified for full bend, not for each part of bend


Manufacturing technology

For ASME B31.1, ASME B31.3, DL/T 5366-2014 seamless pipe will always use Wl=1.0. For electric-welded pipe Wl will be specified from database. More...

When using  GOST 32388-2013, pipe physical properties are taken from different materials databases depending on pipe type (seamless/welded).


Material from materials database

Presence of flanges

Number of flanges must be selected. Flanges are rigid elements and prevent cross-section ovalization. Flanges affect the flexibility factor and stress intensification factor.

  • none - no flanges, elbow is welded to pipes

  • one flange - one end is connected with a flange, while the other end is welded

  • two flanges - both ends are connected with flanges

Position of welds

Position of welds: in the bend plane, in the plane perpendicular to the bend plane. See fig. 1

Nominal wall thickness, S

Nominal (actual) wall thickness

Mill tolerance, С1

Mill tolerance at the time of production. More...

When analyzing based on RD 10-249-98 (section, 3 mill tolerance values must be input (С1=С11+С12): external, neutral and internal bend section, with a difference equal to the value of С12. More...

Corrosion and wear allowance, С2

Corrosion and wear allowance (working mill tolerance) for wall thickness. More...

Do not check internal bend wall thickness

According to RD 10-249-98 section "for extruded elbows manufactured in a closed press, or for bends manufactured on machinery with high-frequency currents and axial preload, c12 к sR1 allowance must be from 0.05s to 0.1s. c12 к sR3 allowance is 0, and internal bend analysis is not performed.
For extruded elbows with the perpendicular weld along the middle of the elbow length,  c12 к sR3 allowance is 0, while c12 к sR1 allowance must be from 0.05s to 0.1s; in this case, internal elbow analysis is not performed, because this side of the elbow has a higher wall thickening than the K2 factor."


Selected if elbow is manufactured with manual winding

Stress correlation along two axes, r

Based on ISO 14692 section 7.10

Qualified stress, qs

If this field is blank then qs is got from material database

Based on ISO 14692 section 7.8

Internal protective layer thickness

- internal (non-reinforced) protective layer thickness. More...

External protective layer thickness

- external (non-reinforced) protective layer thickness. More...

Toolbar Access

To insert a bend, select the desired node and use the menu option: Insert > Insert Bend > Forged Elbow

To view properties of an existing element: