Heat Induction Bending
Cojafex electric heat induction bending up through 42″ O.D. and 4″ wall, in any radius, angle or plane.
Induction bending, and why it exists
American Pipe Bending runs Cojafex electric heat induction bending. It produces the demanding bends specified in nuclear, chemical, petrochemical and energy work, and in onshore and offshore oil and gas pipeline systems.
The machine bends pipe up through 42″ outside diameter and 4″ wall thickness. Because it is computer controlled, the bend radius, the angle and the plane are all free variables rather than a fixed set the tooling allows. That is what makes multi-plane bending in a single length of pipe possible.
The practical benefit of that is fewer butt welds. Every weld in a piping system is a place to inspect, a place that can fail and a line item in a schedule. Bending a single pipe spool through several planes takes welds out of the run rather than moving them.
Request a quoteHow induction bending works
The Cojafex process replaces the older sand pack method. Heat is induced directly in the pipe wall by circulating electrical current, and every parameter is computer controlled.
Clamp to the pivot arm
The straight pipe is clamped to a pivot arm set to the predetermined bend radius.Position the coil
A single turn induction coil is positioned around the pipe at the start of the bend.Heat and propel
Electric power transmitted through the coil heats a narrow band of the pipe wall, creating a plastic hinge. The pipe is propelled through the coil as the temperature rises and the bend forms inside the heated band.Controlled cooling
Air or water spray cools the band as it leaves the coil, which holds the metallurgical characteristics of the material. Forces are monitored and recorded throughout.Why the heat band is narrow
The whole method turns on heating a narrow band rather than the whole section. The circulating current induced by the coil heats deep in the pipe wall, and the electrical resistivity of the material turns that current into a localised hot zone. Only the metal inside that zone moves.
Controlled heat soak then conducts the heat through and along the wall, which matters on heavy sections where the outside would otherwise soften long before the inside. The result is a plastic hinge that travels with the coil, so the bend forms continuously rather than in one violent movement.
That is the difference from sand pack bending, where the whole section is heated and packed to stop it collapsing. It is slower, it is harder to control, and it leaves the metallurgy in a state a modern specification is unlikely to accept.
What it is specified for
Induction bends hold their wall thickness and their roundness on large sections, which is why they appear where the service is critical: nuclear, chemical, petrochemical, energy and power, onshore pipeline and offshore oil and gas.
ASME B16.49 is the standard that governs factory-made induction bends, and it is what most owner specifications point at. Send yours with the enquiry along with your wall thinning and ovality acceptance limits, and we will confirm before anything is cut that the radius you want is one we can hold.
Off the floor
What to send, and what it costs to leave out
Five numbers describe a bend: outside diameter, wall thickness, centerline radius, bend angle and the tangent length on each end. Add the material, the quantity and the code and the job can be priced. The quote form takes a drawing up to 25 MB in PDF, DWG, DXF, JPG or PNG, and a photograph of a marked-up print is fine.
The things most often left out are the ones that change the price most. Documentation is the first: material test reports, non-destructive testing and heat treatment all have to be priced and scheduled from the start, and retrofitting a package onto a finished bend is slow and sometimes impossible. The delivery date is the second, because it decides whether the job is possible rather than what it costs.
The third is the acceptance criteria. Wall thinning on the outside of the arc and ovality through it are the two numbers a reviewer checks first. Tell us the limits and we will confirm the tightest radius that holds them before anything is cut. Finding the boundary at quote stage costs nothing; finding it at first article costs a length of pipe and a week.
Where a drawing calls out a bend that cannot be made as dimensioned, you will hear about it at quote stage rather than at delivery. That happens more often than it should, usually because an isometric was drawn without a bend schedule and the radius was never checked against the wall. Working back from an isometric to the five numbers each bend needs is routine here, and it normally catches at least one dimension that does not close.
Testing we can provide
Per your bending specification, not ours. Tell us the code and the acceptance criteria and we will say what runs here and what is subcontracted.
Other ways we bend
Wall thickness, radius, material and schedule decide the method. If you are not sure which fits, send the drawing and we will tell you.
Coiling
Helical, spiral wound and serpentine coils, cold, up through 10″ pipe.
Cold Bending
Rotary draw bending on fourteen machines, with mandrels and wiper shoes where the radius needs them.
Mandrel Bending
Ball mandrels and wiper shoes for tight radii and thin walls that would otherwise collapse.
Large Diameter Pipe Bending
The work most shops turn away: up to 42 inch outside diameter and 4 inch wall.
Stainless and Alloy Bending
Stainless, duplex, Hastelloy, titanium and nickel alloys, bent without wrecking the metallurgy.
Custom Pipe Fabrication
Cutting, end prep and fabrication around the bend, so one purchase order covers the package.
Have a drawing? Send it over.
Send a drawing or a sketch and our team will get back to you with a quote.