Grinding welds flat

[Max]

Hi,
I know a lot of people like to grind welds flat both for aesthetic reasons and it makes it harder to be caught by a spinner.
But I was wondering how badly this affects the strength of the weld?
I've tried searching on google for an answer but there seem to be very mixed responses.

[maddox10]

It affects the strength of the weld. But if the weld is done right, it should be exactly as strong as the base material.

On the other hand, doing a weld that well is a job for professionals with the right tools.

Unless the weld is really ugly, or is in the way for other stuff, just leave it be.
Or give it a cosmetic flap disk treatment, but not to flatten it up to the base material.

[blazerbotics]

Grinding it will reduce it's strength, by how much all depends on how good your welds are, what thickness material, penetration etc. I grind my weld where required, but leave them intact if i can. I use a 36grit disc on a backing pad, can use a flap disc, but they tend to be expensive.

[plargen]

It also depends on the type or weld as mig doesn't have as good pentration into the metals as tig or stick but as long as you weld it both sides and only grind 1 it shouldn't cause any issues

[evristow]

Actually when the weld and the grinding are done right it can improve the resistance against impact and fatigue, since the stress concentration factor would be reduced. This is true for subsea pipelines (my work) for instance, aiming to reduce fatigue.

Cheers,
Eduardo