2. Niras AS Location: Bø in Telemark, Norway
World wide supplier of induction bending

3. Why use induction bending?
Geometry
Induction bending allow designers more freedom

4. Why use induction bending?
Flow
Designing piping systems with smooth arcs, no welds and larger radii, reduces turbulence and pressure drop and increase the effectivity of the system.

5. Why use induction bending?
Reduce number of welds *Cost saving designs*
Traditional
6 welded joints
Induction bends
1 welded joint
Induction spool
0 welded joints
Induction bends
2 welded joints

6. Induction bending Basic principle
The principle behind induction bending is to heat up a small cross section of a pipe or profile
to such an extent that plastic deformation can be performed by applying relatively small forces.
The work piece is forced forward through the induction coil while guided by a rotating arm.
Only applying heat to a small section allow high level of control and prevents the pipe or profile
from collapsing.

7. Induction bending Induction heating
An induction coil with alternating current is used to introduce
an electromagnetic force field around a work piece.
The magnetic field induces an electric current(eddy-current)
at the surface of the work piece.
Resistance in the work piece causes the current to generate heat.

8. Induction bending Heat zone
The physical bending of the pipe or profile is done within a controlled heated zone.
The width of the zone is controlled by the air-, induction- and quench spools.

9. Induction bending Temperature control
The temperature of the heated zone is controlled by pyrometers.
Examples of temperature ranges:
Carbon steels (870 – 930 °C)
Duplex / Super Duplex (1050 – 1120 °C)
Nickel alloys (1050 – 1100 °C)
Pyrometers

10. Induction bending Cooling
Cooling is provided by the air spool and primarily
the quench spool(water).
Rate of cooling is essential to control material properties
in most iron based alloys.

11. Induction bending The bending machine:
The bending arm grips the pipe in neutral position and rotates around a fixed point as the pipe is pushed forward.

12. Induction bending Intrados/extrados:
As the pipe moves forward it experiences compression in the intrados of the bend causing material build up and thickening of the pipe.
At the same time the extrados of the pipe experience tension. The tension causes the material to stretch and results in wall thinning.
Full scale pressure testing has shown that in spite of the thinner wall in extrados the pipe will fail in the unaffected portion of the pipe and not in the bent area.
Intrados- compression Extrados- tension
Material build up Wall thinning
Large radii- small effect
Small radii- bigger effect
Calculator:

13. Induction bending Qualification and testing:
The induction bending process can be qualified and parameters locked, equal to a welding qualification, to ensure equal properties for each bend.
Qualification testing
Production testing
Batch testing

14. Induction bending Specifications Test regime has major cost impact
NORSOK M-630,
DNV OS-F101,
ISO , ISO
TR 1120
Customer/company specifications
Test regime has major cost impact

15. Post bending PBHT: Post Bend Heat Treatment
Applicable for most carbon steels and heavy-wall CRA’s
Solution annealing
Normalizing
Quenching
Tempering
Capacity: MT
Temp. range: 580 – 1150 °C
Working zone: 5800 X 2300 X 1000
Qualification: NORSOK M-650/API 5L

16. Post bending Surface finish:
Sand blasting
Pickling and passivation of CRA’s
HNO3 (Nitric acid) HF (Hydrofluoric acid) Citric acid

17. Materials Alloys for bending
All electrically conductive materials can be induction bent.
Suitable for induction bending:
All types of steel
Aluminium
Copper
Nickle alloys
Etc.
If properties can be maintained or enhanced after bending depends on the original condition of the material.

18. Design Profiles Pipe Dimensions: 16 mm and up
(Niras max. OD is 18inches)
Profile dimensions:
Maximum 300 x 600 mm
R up to mm
Angle: 0° °
Selection of profiles

19. Design Niras design criteria http://www.niras.no/downloads.html
If in doubt please contact us
Commonly used

20. Design
Some examples

21. IBP example front page

22. IBP example test scope

23. Case study Burst testing:
In collaboration with Telemark University Collage, Niras investigated the effect of induction bending on fracture location in burst testing.
Material grades investigated were Duplex (UNS S31803) and Grade 316 (UNS S31600).
All tests performed showed fracture in the tangent.