This was a reply in another post - separated out as now a different subject ....
I remember from when I first learnt normal arc welding ... that if you were butt joining two pieces of box section or wanted to provide extra strength on a box section member that you applied strengthening plates on both sides of the widest section ... but importantly you only welded along the long edge - and not all 4 sides.
The advice being that the weld should follow the load, and if you welded 'across' you actually weakened rather than strengthened ... sketch may be better than description:
http://tinyurl.com/2bsk7x
is this still advice still the same ? ... been 25yrs since I last did this.
I could of course use an angled 'butt' under the plates, but it will not be easy to cut accurately in-situ.
When I last did this the strengthening plates were usually thicker than the box section ... probably 4mm, anybody know if there is a guide rule as to how much thicker the plates should be compared to main member (i.e 2 times or whatever)
For more strength (if you cut the rusty section out), cut at an angle then don't grind the welds down if it dosen't have to be smooth.
I remember from when I first learnt normal arc welding ... that if you were butt joining two pieces of box section or wanted to provide extra strength on a box section member that you applied strengthening plates on both sides of the widest section ... but importantly you only welded along the long edge - and not all 4 sides.
The advice being that the weld should follow the load, and if you welded 'across' you actually weakened rather than strengthened ... sketch may be better than description:
http://tinyurl.com/2bsk7x
is this still advice still the same ? ... been 25yrs since I last did this.
I could of course use an angled 'butt' under the plates, but it will not be easy to cut accurately in-situ.
When I last did this the strengthening plates were usually thicker than the box section ... probably 4mm, anybody know if there is a guide rule as to how much thicker the plates should be compared to main member (i.e 2 times or whatever)