Gotta remember, even the bolted on hooks are welded to the plate you bolt on.
A weld is a weld. If one can weld the hook to the loader as good as the weld is to the plate, the chances of a welded hook flying off is equal, whether welded or bolted.
Guys,
I am gonna chime in here - as a welder (not a great one however) the WELD to the bucket is fine - but remember, the footprint of a weld on both sides of a hook are placing a hellva lot of pressure on the THAT spot on the bucket!!!
SO - if someone was to jerk the hell out of the bucket hook - all of that force will be applied to a small area OF THE BUCKET, sure the weld should hold, but the bucket could deform.
When a hook is welded to a plate - the plate is is inherently thicker than the bucket material - thus the pressure when BOLTED to the bucket places a stress on a larger surface area. Now the pressure is placed on the bolts!
I would make sure that the grade of bolts far exceeds the weld breaking strength. The washer used on the head side and nut side of the bucket will also decrease the pressure at that specific point.
Weld on hooks are fine - guessing over the last 50 years more than 80% of all hooks are welded on and 99.99% of those are probably fine. I wanted to weld on a plate and have that plate rise up a bit higher than the bucket edge- When I roll the bucket - the chain bangs up the upper lip of the bucket.....and being a finicky a$$ - I could not stand it!!!!!
This is 2 .500 inch plates with the hook - ground and welded. Cannot remember what rod I used. - and dont look at that bubble gum to hard!