Lifting at 830°C

[AndStar]

Hi!
I'm a mechanical engineer of "Below the Hook" liftng devices. I'm from Italy and this is my first thread on eng tips. I hope that my English will be comprensible.
I have a particular situation because a shaft (6,2t) must be placed into a furnace for heating until 865°C. After the heating cycle the shaft must be moved from the furnace (830°C).

The first try with an eyebolt showed high risk of load release because the eye bolt was higly deformed. The thread resisted.
No we have decided to weld a plate to the shaft (after the heat treatment the shaft will be machined). Plate has a slotted hole for a foundry hook.
My dubt is on mechanical properties of structural steel (plate) at 830°C because most of European Norms doesn't furnish data over 600°C. I found in a fire design norm these values (interpolated)

Room temperature 830°C
Re = 345 MPa (Yield) 33 MPa
E = 210000 MPa (Elastic modulus) 17560 MPa

For your opinion are these values on safe side?

Thanks in advance, AS

 

[metengr]

I would not recommend using your below the hook lift with carbon steel welded to the shaft. You need a manipulator like those used in a forging shop to handle material removal from furnaces. Welding a carbon steel plate and subjecting it to heating and soaking as the shaft material is too risky for application of load.

 

[Compositepro]

Make a lifting hook that hooks around the shaft from steel plate. The bulk of the hook will not get anywhere near the shaft temperature. Large, hot forgings are are handled all the time with steel lifting devices.

 

[AndStar]

Thanks for the answers! The problem is that is not disponible a manipulator and due to low number of shafts is economically not convenient build a manipulator or dedicated lifting device. I attach a picture of the lifting assembly to explain better the situation. The shaft will have a rim on the top anr it will be placed into the furnace vertically.

 

[metengr]

Work with this company to have a proper and safe device.

http://www.bushman.com/index.php/content/below_the_hook/tongs