Welding a bolted together structure, safety

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Hi, I have a bolted together steel tubing frame (for a table).I would like to weld it to get greater rigidity.I'm guessing it's a bad idea to leave the current bolts in, since they are zinc plated.I would like to replace the zinc plated bolts with another kind of bolt that is safe. I would be nice to use the existing bolt holes to hold the material while the weld is being done.What type of bolt is safe? Thanks. Oh, and as a side note, after it is welding, I won't be counting on the bolts for mechanical strength.
Reply:You could go to a hardware store and buy standard nuts and bolts that are not zinc plated.  I believe they are a little more $ than the zinc plated bolts, since they going to be a higher grade bolt.  Alternatively, you could weld the table together with the zinc bolts in place and just make sure you don't heat the bolts so much that they release the toxic fumes HH187Harris O/AInfrared thermometerHalf a dozen angle grinders
Reply:Just weld the bolts. That electroplated zinc isn't going to do much unless you are trying to tig weld on it. For mig?? I weld through it all the time.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:unless you plan to weld over the bolt you can leave them in. Or take them out as you go. you could probably tack around the bolted connection. Then take the bolt out and keep on doing that.That's what I would personally do.Also unless the current bolts keep backing off and get loose, welding won't increase rigidity as much as adding braces and gussets will.
Reply:Wow, Thanks everyone for the quick response. That's amazing.I will buy new bolts, just because I am a newbie, and to be honest, I'd rather spend $20 on bolts and not risk it.. I did see some black colored bolts, I don't think they are zinc plated (but I will confirm) I'm really not confident enough in my ability to "make sure the bolts don't get too hot". I will think I will add some more brackets/bracing to help add rigidity too.. that's a good point.
Reply:As mentioned, just welding things together instead of having them bolted together won't necessarily make the structure any more rigid.Bracing or gusseting or changing the structure -can- make it more rigid.  But that could be a whole lot more work that just bolting it together.    That can be the whole tube-fab and tube bender and fishmouth 'thing'.And if the existing tubing is galvanized or painted, welding and/or the prep for welding will remove the zinc or paint where the welding occurred.  Meaning the welds and around them rust faster than the tube, unless you take care to re-paint or cold-galvanize things.  Yet more steps to do to do the job 'right'.  The best laid schemes ... Gang oft agley ...
Reply:Originally Posted by MoonRiseAs mentioned, just welding things together instead of having them bolted together won't necessarily make the structure any more rigid.Bracing or gusseting or changing the structure -can- make it more rigid.  But that could be a whole lot more work that just bolting it together.    That can be the whole tube-fab and tube bender and fishmouth 'thing'.And if the existing tubing is galvanized or painted, welding and/or the prep for welding will remove the zinc or paint where the welding occurred.  Meaning the welds and around them rust faster than the tube, unless you take care to re-paint or cold-galvanize things.  Yet more steps to do to do the job 'right'.
Reply:Post a picture.  If we know the design, we can possibly suggest where to add a few small braces, that can make a big difference in its rigidity.