Welds on steel structures

[Grad1]

Hi,
Which welds prevent the transmission of electric currents to the structure? Our project involves a weld that was not completed during construction and was noted during a final inspection. The connection needs to be completed to pprevent eccentric loading of the connection. The connection is at a column-beam-brace. Electric/arc welding methods cannot be used as it will interfere with the electronic weigh cells on the structure. The structure is a resin vessel. Bolting an angle on is tricky due to geometric constraints but probably can be done. Will MIG welding work? Any comments valued! Thanks

 

[CWIC]

I'm a LITTLE confused by your post. You mention "...electric/arc welding methods cannot be used...' Metallic Inert Gas (MIG) welding is an arc (electric) process.

I have worked on a couple of projects were any stray electrical currents (including any eddy currents) were prohibited. What about arc welding placing the workpiece connection as close as possible to where the work is being performed and providing a true ground connetion for the welding equipment and structure?

 

[Grad1]

Apologies for my ignorance! What I meant was gas welding the connection being the best solution. The use of electric currents is risky here as there is potential for them to be transmitted through the structure. Therefore we require a non-current based method. What I was really asking was whether gas welding will achieve this? Thanks

 

[SlideRuleEra]

Another non-electic weld uses an exothermic reaction, typically a rapidly burning powder to produce the heat needed for the weld. A common trade name is "Cadweld". A Google search on this may tell you if this approach is useful for your application. It is often applied to welding large electrical conductors, often the grounding system on industrial sites.

 

[CWIC]

Any welding process not listed in the D1.1 as prequalified (including code approved processes) require procedure/performance qualification. This would include the TW and OFW processes suggested.

It sounds like mechanical fastening would be the most practical method of completing your connection.

 

[unclesyd]

Somebody more familiar with weigh cells jump in. We welded in and around all types of weigh cell supports all the time. There almost constant welding on vibrator pads on the tank themselves. It seems like one could uncouple the weigh cells electrically and ground the welding machine on the farthest part to be welded from the cell. I don’t see how something that needs a brace supporting something else hasn’t been made “earthy”, connected to the plant ground.

 

[Grad1]

For you information guys, we have decided to bolt an angle on instead of welding it! Thanks!