haggis
Mechanical
- May 18, 2002
- 290
Hi all,
I'll post this thread in the Materials forum as I am convinced that my problem is not structural in nature.
We have an overhead monorail conveyor which uses S4 x 7.7 C-1045 rail. The rail is supported every 9'-0" with a vertical hanger and clip such that the clip is welded all round to the top of the S4 giving 9" of 3/16" fillet weld in tension. The vertical leg of the clip is welded to the hanger with a total of 5" of 3/16" fillet in shear and across the top for 2" of 3/16" fillet in tension.
Hanger is L 3 x3 x 1/4", clip is L 3 x3 x 3/8 A36.
The C-1045 rail splice is a 3/16" butt weld all round , ground flush and has a L 2 x 2 1/2 x1/4" strongback, long leg vertical, stradling the joint on the top flange. Also welded all round.
Occasionaly we are having weld failures at either the rail splice or at the hanger clip.
When the construction work is done during plant down time, the welders (all certified) are monitored fairly closely and all welds are inspected by an independant inspection firm. The only thing I can't say for sure is if the welders are taking the time to preheat the C-1045.
This conveyor system is run on a three shift basis and load of approx 1000lbs cycles across the rail splices and past the hangers at a rate of approx 1200 times a day. No impact loads are present.
So after this long winded description, my question is: Can fatigue at these types of joints using the methods and materials mentioned, be accurately estimated so that preventative maintenance can be done or would a crystal ball be a good investment. Maintenance do conduct periodic checks but when a crack is discovered, failure is too close for comfort. Inspection is better than nothing but a crack can develop 2 minutes after.
Thanks for any help or opinions in advance.
I'll post this thread in the Materials forum as I am convinced that my problem is not structural in nature.
We have an overhead monorail conveyor which uses S4 x 7.7 C-1045 rail. The rail is supported every 9'-0" with a vertical hanger and clip such that the clip is welded all round to the top of the S4 giving 9" of 3/16" fillet weld in tension. The vertical leg of the clip is welded to the hanger with a total of 5" of 3/16" fillet in shear and across the top for 2" of 3/16" fillet in tension.
Hanger is L 3 x3 x 1/4", clip is L 3 x3 x 3/8 A36.
The C-1045 rail splice is a 3/16" butt weld all round , ground flush and has a L 2 x 2 1/2 x1/4" strongback, long leg vertical, stradling the joint on the top flange. Also welded all round.
Occasionaly we are having weld failures at either the rail splice or at the hanger clip.
When the construction work is done during plant down time, the welders (all certified) are monitored fairly closely and all welds are inspected by an independant inspection firm. The only thing I can't say for sure is if the welders are taking the time to preheat the C-1045.
This conveyor system is run on a three shift basis and load of approx 1000lbs cycles across the rail splices and past the hangers at a rate of approx 1200 times a day. No impact loads are present.
So after this long winded description, my question is: Can fatigue at these types of joints using the methods and materials mentioned, be accurately estimated so that preventative maintenance can be done or would a crystal ball be a good investment. Maintenance do conduct periodic checks but when a crack is discovered, failure is too close for comfort. Inspection is better than nothing but a crack can develop 2 minutes after.
Thanks for any help or opinions in advance.
