Weld Capacity Between A36 and Forged Steel 2

[TBKS]

I need to determine the load capacity of a lifting device that has forged steel lifting hooks welded onto a web of an A36 S-beam. I'm not sure what the alloy is of the forged steel lifting hooks (I am assuming Grade 60 or 80). How does welding affect forged steel? What code governs this connection (if AWS D1.1, what section)? Can I assign a strength value to the weld/base material? I do not know how the weld process took place, or under what conditions, but I believe it was done in haste, such as a field weld.

Any insight would be greatly appreciated. Thanks!

 

[metengr]

I'm not sure what the alloy is of the forged steel lifting hooks (I am assuming Grade 60 or 80). How does welding affect forged steel? What code governs this connection (if AWS D1.1, what section)? Can I assign a strength value to the weld/base material? I do not know how the weld process took place, or under what conditions, but I believe it was done in haste, such as a field weld.

Don't assume anything when it comes to lifting and rigging. By the nature of your question(s), you need to seek some engineering expertise regarding the design of the lifting hook and what exactly was done. You have too many variables to provide any meaningful help.

 

[TBKS]

Metengr,

Thanks for the reply. You are absolutely right--there are a lot of variables in my origninal question. Can you provide any general information from your experience about how the strength capacity of the forged steel might be impacted by a weld?

Thanks!

 

[metengr]

TBKS;
The concern I have is with the original heat treatment condition of the lifting hook. Forging is a method of working the material to obtain desired shape and grain flow. The actual strength properties are obtained thru a specific heat treatment. Unless you know the specific requirements for heat treatment needed in service and the welding process that was used you can be all over the map in terms of mechanical properties.

Get some help to assure you have a properly designed lifting lug that was attached correctly.

 

[gtaw]

Do you know what the material of the forged hook is? What is the chemistry? Is it meant to be welded?

If this is an assembly that was fabricated in the field by the workers, you have no easy way of determining what the weldability of the hook is or what filler metal was used, what preheat was used (if any), etc.

As "metengr" says, "too many variables" and too many unknowns.

Don't trust anything that was fabricated using components that were "handy" at the time.

Best regards - Al

 

[attilon]

Hi,

The people are right. Don't trust anything when it comes to lifting and rigging. But when you must deal with these kind of problems, you can always rely on old German welding school rules:
1. Modify your structure in a way that all welds should work only on compression. This way your weld will be as strong as your base metal. Actually material holds material, and welds only position the material. This way you will know exatctly when the structure will fail.
2. The best weld is the weld you don't have to do at all.
3. A little Ni is always very good for the welds in the filler metal.
4. Make some controll spots on the key points of the structure, and measure the distance between them every day in the first week, then you see if it deformates or not.

Good luck.
Attila.