Niras ASLocation: Bø in Telemark, Norway

World wide supplier of induction bending

Why use induction bending?

Geometry

Induction bending allow designers more freedom

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.

Why use induction bending?

Reduce number of welds *Cost saving designs*

Traditional6 welded joints

Induction spool0 welded joints

Induction bends1 welded joint

Induction bends2 welded joints

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.

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.

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.

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

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.

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.

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:http://www.niras.no/downloads.html

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.

1. Qualification testing2. Production testing 3. Batch testing

Induction bending

Specifications

• NORSOK M-630, • DNV OS-F101, • ISO 15590-1, ISO 13628-15• TR 1120• Customer/company specifications

Test regime has major cost impact

Post bending

PBHT:Post Bend Heat Treatment

Applicable for most carbon steels and heavy-wall CRA’s

- Solution annealing- Normalizing- Quenching - Tempering

Capacity: 3.75 MTTemp. range: 580 – 1150 °CWorking zone: 5800 X 2300 X 1000Qualification: NORSOK M-650/API 5L

Post bending

Surface finish:

Sand blasting

Pickling and passivation of CRA’s

HNO3 (Nitric acid) HF (Hydrofluoric acid) Citric acid

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.

Design

Profiles

Pipe Dimensions: 16 mm and up(Niras max. OD is 18inches)

Profile dimensions: Maximum 300 x 600 mm R up to 22 000 mmAngle: 0° - 300°

Selection of profiles

Design

Niras design criteria

http://www.niras.no/downloads.htmlIf in doubt please contact us

Commonly used

Design

Some examples

IBP example front page

IBP example test scope

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.