Bending P91 with Inductaflex
By the end of this decade it is estimated that 300 to 400 new power plants will be built across the world. Much of the pipe that carries high-pressure steam to the turbines now is made from a newer-grade chromium-molybdenum alloy, 9 %Cr-1Mo-V (P91) steel. The new grade offers a much better strength-to-weight ratio than the old standby, 2¼% Cr-1Mo (P22) steel. P91 is much more wear resistant and stronger than P22 due to its higher chrome content, for example:
A 26-inch-diameter main steam line made from P91 can have a wall thickness of 2¼ in. With P22, you’d be looking at a product almost 5 in thick. Therefore, designers choose this material.
P91 seamless material ready for Induction Bending 20” x 3” wall thickness.
With the Inductaflex machine it is specifically designed to handle this material and guarantee a quality bend every time to the standards imposed by the power generation industry.
Features like a 3rd pyrometer that reads the inside temperature of the pipe during the “soak through period” prior to commencing the bend. This is important as the bend temperature throughout the wall thickness of this material is critical. With most induction bending machines the preferred operating frequency is 1000 Hz. At this frequency, the “reference depth” (how much the electromagnetic field penetrates the material) is around 0.7” (17.8mm). After that you are relying on thermal conductivity to do the work, known as the “soak through period”
3 axis control of the inductor coil control ensure that the tangent area of the material undergoes the heating process as the bend. Movement of the coil in the X Y axis also controls wall thinning to a minimum while maintaining the ovality is held to industry standards.
Inductaflex also offers accurate pipe temperature control throughout the bend via 2 additional pyrometers. This ensure the material chemical properties are controlled and a constant temperature over the full length of the bend. All-important records are stored in the machine so that the customer gets full documentation of the bending process.
“With Inductaflex, you get more than just a machine, you get our expertise in handling & bending and any kind of material to customer’s specifications”
We can provide procedures for an array of materials through our years of experience and testing. Our data sheets include;
- Storage of the material
- Record keeping and full tractability of Induction Bent pipe.
- Handling material
- Contamination procedure for induction bending machines.
- Pre-bending checks
- Bending the material
- Post bending checks, none destructive testing procedures
- Post bending Heat treatment P91
- Supporting documentation