| Specifications︰ | Induction Bending is a controlled means of bending pipes through the application of local heating using high frequency induced electrical power.
Originally used for the purpose of surface hardening steels, induction technology when used in pipe bending consists basically of an induction coil placed around the pipe to be bent. The induction coil heats a narrow, circumferential section of the pipe to a temperature of between 850 and 1100 degrees Celsius (dependant on the material to be formed). As the correct bending temperature range is reached, the pipe is moved slowly through the induction coil whilst the bending force is applied by a fixed radius arm arrangement.
As the bending occurs, the adjacent area forward of the heat band is water or air quenched (or may be allowed to cool naturally) thereby allowing the cool material to either side of the ‘heat band’ to retain the integrity of the original material as best as possible. This means of distortion control provides excellent dimensional accuracy and repeatability.
Achieved tolerances when forming induction bends are to some extent governed by the materials in hand and the required format of the finished product however the following are the minimum standards to which Induction Pipe Bending UK Ltd operate:
Angle:
Radius:
Linear distances:
Linear plane:
+ / - 0.5 degrees
+ / - 1.0% of nominal
+ / - 3.0mm (1.5” to 12” NB & + / - 5.0mm from 12” to 20” NB)
+ / - 1.0% of centre line radius
Although induction bending produces excellent results as far as physical properties are concerned, it must be noted that there are two important considerations required – firstly the reduction in wall thickness at the outside (extrados) of the bend and secondly the degree of ovality which is present.
The induction pipe bending process uses induction heating to produce highly accurate bends. The quality of induction bends is superior to the elbow fitting. Hydro burst tests show that spools with induction bends fail in the straight pipe and not in the bend, whereas in comparable elbow-based systems the elbow (inside radius) is always the first to burst. Stress calculations confirm this. The natural tendency to have a thicker inside wall thus proves to be advantageous and ensures that the bend exceeds the strength of the straight pipe. Many companies have exclusively chosen Cojafex equipment for their induction bending. These benders are used in the following industries:
Chemical and petrochemical
Power generation
Pipeline, on and offshore, including compressor and pump stations
Ship building
Construction (structural shapes)
ASME B16.9-2001
ASME B31
MSS SP-75-1998 |
| Standard Met︰ |
ASME B16.9-2001 Factory-Made Wrought Steel Buttwelding Induction Bends for Transportation and Distribution Systems
This Standard covers design, material, manufacturing, testing, marking, and inspection requirements for factory-made pipeline bends of carbon steel materials having controlled chemistry and mechanical properties, produced by the induction bending process, with or without tangents. This Standard covers induction bends for transportation and distribution piping applications (e.g., ASME B31.4, B31.8, and B31.11) Process and power piping have differing requirements and materials that may not be appropriate for the restrictions and examinations described herein, and therefore are not included in this Standard.
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Specification:
ASME B16.9-2001
ASME B31
MSS SP-75-1998
Pipe outside diameter: ■ φ25-φ1450
Bend radius:3-10m(9.84f-32.8f)
Max wall thickness: 120mm(4.7in)
Angle≤90°
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