Niras AS Location: 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* Traditional 6 welded joints Induction spool 0 welded joints Induction bends 1 welded joint Induction bends 2 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:

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 testing 2.Production testing 3.Batch testing

Induction bending Specifications NORSOK M-630, DNV OS-F101, ISO , ISO 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 MT Temp. range: 580 – 1150 °C Working zone:5800 X 2300 X 1000 Qualification: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 mm Angle: 0° - 300° Selection of profiles

Design Niras design criteria If 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.

HSE improvements Traditional use of HNO 3 /HF mixtures Described in ASTM A380 and ASTM A967 Dangerous for operators and environment Especially Hydrofluoric acid and hexavalent chromium Dangerous and costly waste management Heavy metal hydroxides and residual hexavalent chromium Risk of over-pickling and surface damage if not correctly performed HSE Challenge Pickling and passivation of CRA’s: HNO 3 (Nitric acid) HF (Hydrofluoric acid)

HSE improvements Alternative method for cleaning and passivation Described in ASTM A967 Citric acid formulations No risk for operators or environment No waste management – can be released directly into ordinary sewer system after use No risk of overpickling and surface damage No HSE Challenge Niras has investigated the use of citric acid systems Excellent cleaning and passivation properties Efficient removal of surface free iron contamination Extremely low removal of surface chromium – in contrast to the traditional HNO3/HF systems Enrichment of surface chromium content Provides protective oxide layers similar to or thicker than traditional HNO3/HF systems (for test details please contact Niras) Pickling and passivation of CRA’s: Citric acid