Brad93
Member
- Messages
- 17,570
- Location
- Essex, United Kingdom
Basics: ship to shore conveyor of 20-30 years old, 3 shipments a week, thousands of tonnes of ballast. One end supported by two pillow blocks housing bearings on 4" solid bar. Conveyor 70m long. Other end hopper that is suspended by winch at 65m point raised and lowered on tide. 8 tonne dropped by digger into hopper per bucket. A lot of torsional force as you can imagine. At the bearing end there is a walkway so the space frame arrangement the rest of the conveyor is made out of (showing no problems) is replaced by about 8m of channel.
The Problem. Cracking of channel section 400x100 with 15mm flanges (exact section unknown) 3 meters and 6 meters from bearings.
Pictures speak a thousand words so ive attached some. 1st and 2nd repair shown from outside and inside.
Have been asked to do the repair this time as three previous repairs have failed.
1st Repair: The crack in the channel has been welded, and a 15mm thick plate fully welded over the cracked section. 10mm plate welded over the flanges top and bottom. Result: Crack straight through the 15mm repair plate, original crack in beam re-occurred through centre of weld. Welds cracked on top and bottom plate.
2nd Repair: 12mm Plate bolted using M24 bolts, 4 each side of crack. Holes burned through broken plate and channel with oxyacetylene. result: Plate bent in both X & Y Plane.
3rd Repair (Full length Crack in the other channel): 600 x 250 x 20mm Plate poorly welded with ESAB 6013 inside channel. Outside 12mm small plate of 170mm x 250mm poorly welded over crack.
Small 10mm plate welded on top flange of beam. RESULT: Welds on top plate already cracked. Only been in place a few weeks by the look of the small amount of rust in a marine environment.
We have been called in as we do the jobs other guys simply can't do or can't do in the time frame/cost allowance. Being rope access technicians we don't need scaffolding, safety boats, cranes etc which takes a large cost out of the job.
Anyhow i will update with the progress as it goes on, included the proposals i put forward for reinforcing the structure of the conveyor with a space frame above the conveyor rather than below how the rest of it is.
The Problem. Cracking of channel section 400x100 with 15mm flanges (exact section unknown) 3 meters and 6 meters from bearings.
Pictures speak a thousand words so ive attached some. 1st and 2nd repair shown from outside and inside.
Have been asked to do the repair this time as three previous repairs have failed.
1st Repair: The crack in the channel has been welded, and a 15mm thick plate fully welded over the cracked section. 10mm plate welded over the flanges top and bottom. Result: Crack straight through the 15mm repair plate, original crack in beam re-occurred through centre of weld. Welds cracked on top and bottom plate.
2nd Repair: 12mm Plate bolted using M24 bolts, 4 each side of crack. Holes burned through broken plate and channel with oxyacetylene. result: Plate bent in both X & Y Plane.
3rd Repair (Full length Crack in the other channel): 600 x 250 x 20mm Plate poorly welded with ESAB 6013 inside channel. Outside 12mm small plate of 170mm x 250mm poorly welded over crack.
Small 10mm plate welded on top flange of beam. RESULT: Welds on top plate already cracked. Only been in place a few weeks by the look of the small amount of rust in a marine environment.
We have been called in as we do the jobs other guys simply can't do or can't do in the time frame/cost allowance. Being rope access technicians we don't need scaffolding, safety boats, cranes etc which takes a large cost out of the job.
Anyhow i will update with the progress as it goes on, included the proposals i put forward for reinforcing the structure of the conveyor with a space frame above the conveyor rather than below how the rest of it is.