# welding unistrut clamps.



## gpop

When you run unistrut (stainless) vertical in a area with a high level of vibration it seems the clamp always come loose and slip down. It might take years but every make and model of clamp seems to do this (mild steel is not to bad as it rusts and gives the clamp something to grip)

As a patch we tig the bottom clamp or use a spring nut and a square washer to act as a stop if the conduit slips. (normally years after original install)

I was wondering if you hooked a spot welder to the clamp after the conduit was installed (ground on the unistrut and stinger on the clamp) if you could get the contact points between the clamp and unistut to weld. Now it wouldn't be that strong that you couldn't wiggle it and snap it off and it defiantly wouldn't hold up to a couple of silverback mechanics hanging of it but it should stop the clamp from slipping. 

Any thoughts?


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## splatz

I never thought of that, it sounds like it should work. 

I have just deformed the channel a little to make sure things don't slide.


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## Cow

Hmm, good one.


We've wired some grain mills, getting ready to do another here shortly, but we use regular strut for those and weld it to the the frame work for vibration reasons. But, like you said, we've never had an issue, that I know of, with the strut straps sliding down.


I can't think of any place we've ran stainless that has had the issue you're describing. Interesting problem, sounds like a pain in the @ss to deal with though.


I wonder if there is a way to grind a notch with a skinny wheel, die grinder, whatever that would keep the strap from sliding.


On second thought, maybe welding a small ss nut or similar to the face of the strut right up against the bottom of the strut strap? At least then you could still remove the strap if needed.


Just throwing out ideas here...


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## Chops146

I have used spring nut, square washer and bolt for this. One rack where they didn't want the squares showing I used a spring nut and bolt, I think it was 1½", and turned it until it was grinding into the block behind the strut.


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## Flyingsod

I’m no longer working as an electrician so my code book is stowed. I’m pretty sure there is a code prohibition about welding conduit straps shut. Welding the strap to the strut is possibly ok but welding the strap closed is prolly a violation. I know people that interpreted it as absolutely no welding on any conduit or clamps. Wish I could read again now. 


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## Forge Boyz

My brother is a hobbyist welder so I asked him about this. He says it's too great of an area for a spot welder to work. They concentrate the weld in a very small spot. 

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## John Valdes

I have never used a welder once in my whole career. Except to practice with scrap on the night shift when there was little else to do.

I have never really seen an application where an electrician needed to weld anything or have anything welded.
In fact I was under the impression welding and electrical systems/support were a "No No"

A foreman in a plant who decided to practice his welding, decided to weld a Hoffman enclosure to strut once. To save time was his excuse.
It looked horrible. Even scorched the inside of that expensive enclosure.
I once had a ship yard electrician ask me "why not tack weld" the 2" EMT conduit to the strut to save time and not need any strut clamps. HUH?

Like I said. Never welded any electrical parts in my life and see no reason to start now.
I always thought it was hack. And silly.
I mean we are not pipe fitters. We have a product or part to do every job we can ever come up against. Welding something was never even considered.


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## Cow

We weld all the time.

Ag services(on tube frame stanchions), strut brackets, transformer supports, conduit layout jigs for switchgear underground stubups, etc etc, on and on.

In my opinion, it's fairly limiting, if the only things an electrician can build are the ones they make strut brackets or electrical hardware for.

I've seen some real contraptions electricians have built out of strut and strut brackets, that would of been half as complicated and take half the time and resources, if they had just been welded.

For instance, I built this stanchion and had it powdercoated, because there wasn't enough wall space for this equipment. Another EC attached all the electrical equipment to it though.


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## gpop

John Valdes said:


> I have never used a welder once in my whole career. Except to practice with scrap on the night shift when there was little else to do.
> 
> I have never really seen an application where an electrician needed to weld anything or have anything welded.
> In fact I was under the impression welding and electrical systems/support were a "No No"
> 
> A foreman in a plant who decided to practice his welding, decided to weld a Hoffman enclosure to strut once. To save time was his excuse.
> It looked horrible. Even scorched the inside of that expensive enclosure.
> I once had a ship yard electrician ask me "why not tack weld" the 2" EMT conduit to the strut to save time and not need any strut clamps. HUH?
> 
> Like I said. Never welded any electrical parts in my life and see no reason to start now.
> I always thought it was hack. And silly.
> I mean we are not pipe fitters. We have a product or part to do every job we can ever come up against. Welding something was never even considered.


Working in a food grade stainless plant means welding as there are so many rules about making sure that the conduit and supports do not harbor food for bacteria. It why most strut is mounted vertical. 

I have seen a new design for the food industry that is half round with a slot as a replacement for unistrut in SS so maybe that is the answer. In the mean time i might just borrow a spot weld timer and see what happens on some scrap. If it can tack the 4 small spots where the strut clamp grips it might work. The conduit is pvc coated ridgid (which may be the reason it loosens over time as the rubber between the strut and the conduit wears and compresses) So i do not think that a tiny weld will affect it.


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## gpop

Cow said:


> We weld all the time.
> 
> Ag services(on tube frame stanchions), strut brackets, transformer supports, conduit layout jigs for switchgear underground stubups, etc etc, on and on.
> 
> In my opinion, it's fairly limiting, if the only things an electrician can build are the ones they make strut brackets or electrical hardware for.
> 
> I've seen some real contraptions electricians have built out of strut and strut brackets, that would of been half as complicated and take half the time and resources, if they had just been welded.
> 
> For instance, I built this stanchion and had it powdercoated, because there wasn't enough wall space for this equipment. Another EC attached all the electrical equipment to it though.


Isnt that a damp area with that ammonia vessel behind it (ice). Do the vfds hold up ok or do they grow mold?


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## Flyingsod

I’m surprised you’re allowed to use strut. That little lip curl ya about impossible for the porters to clean. Also when I did extensive work in a bakery the rule was all pipe work had to be min 3” off the wall to facilitate wall cleaning. We had to have a sheet metal co fab some stainless standoffs. 


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## gpop

Flyingsod said:


> I’m surprised you’re allowed to use strut. That little lip curl ya about impossible for the porters to clean. Also when I did extensive work in a bakery the rule was all pipe work had to be min 3” off the wall to facilitate wall cleaning. We had to have a sheet metal co fab some stainless standoffs.
> 
> 
> Sent from my iPhone using Tapatalk


Bakery's and places that use dry powder are way worse than a place that does liquids.


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## Jlarson

I wouldn't allow that just because it might leave stray arc marks. 



We typically use food grade strut or ss angle and U bolts.


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## glen1971

John Valdes said:


> I have never used a welder once in my whole career. Except to practice with scrap on the night shift when there was little else to do.
> 
> I have never really seen an application where an electrician needed to weld anything or have anything welded.
> In fact I was under the impression welding and electrical systems/support were a "No No"
> 
> A foreman in a plant who decided to practice his welding, decided to weld a Hoffman enclosure to strut once. To save time was his excuse.
> It looked horrible. Even scorched the inside of that expensive enclosure.
> I once had a ship yard electrician ask me "why not tack weld" the 2" EMT conduit to the strut to save time and not need any strut clamps. HUH?
> 
> Like I said. Never welded any electrical parts in my life and see no reason to start now.
> I always thought it was hack. And silly.
> I mean we are not pipe fitters. We have a product or part to do every job we can ever come up against. Welding something was never even considered.


Guess it all depends on the area(s) that one works.. We've welded thousands of supports over the years for electrical cable tray, unistrut, and structural steel (C-Channel, square tubing etc) for panels, disconnects, Junction Boxes, conduit runs, etc.. Some places where structural steel was fireproofed, they had very strict installation guidelines on how to build electrical supports so that they could later be properly fireproofed. One place had the switchgear welded to 4" C-channel that were set in place in the concrete floor.


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## Southeast Power

I would just give the strut a nice squeeze with a pair of channel lock and it buggers up the channel enough to where the straps cant slide.

I have found a few straps and even conduits welded and its always some cross over trade Hack that has done it. It really sucks for the next guy that ends up having to bring out a grinder to do some simple demo.

We had a rack made like COW posted for a distribution panel but, I think I would draw the line at welding straps. Maybe consider vibration proof nuts or something else.


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## splatz

Actually if you just nick the channel with a bandsaw, and drive a tiny sheet metal screw into the kerf, it isn't going anywhere, but if you remove the screw, you can move things around if you ever need to.


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## Helmut

Count me in on the cone nut, bolt and washer crowd.

I wouldn't weld it.


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## macmikeman

I haven't pulled out any of my welding machines in decades from the gang boxes they live in , but yes I can walk around the tarmac at Honolulu International Airport and point out probably a thousand pieces of strut people in my employ welded to jetways and other metal supports. Never tried welding a strap though, just mounting the unistrut to metal as a support means. If you have a guy working all day 5 days a week doing nothing else but welding like I had , you can cut a lot of time out of a project and it is a very good way to make some money , but you need something like that to make it worth the setup. You guys talk about mounting panels on plywood all the time. Well, we were mounting plate steel to iron column's and then spot welding panels to that.


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## Flyingsod

Everything Can be done with strut but some things look way better with welded structural steel. Take for instance hanging a transformer. Get a fabricator to build a shelf for it and it looks like part of the building meant to be there. On the other hand hang it from all thread and strut like we often do and it’s janky looking like an after thought. Strut to me (while I used it and really liked working with it) is like an erector set for adults. It’s toyish looking. 

I love that idea about squeezing the strut as long as you can keep from scratching it. Scratches are places for bacteria to grow. That’s also a concern with cutting or adding a set screw. 


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## Chops146

gpop said:


> Working in a food grade stainless plant means welding as there are so many rules about making sure that the conduit and supports do not harbor food for bacteria. It why most strut is mounted vertical.
> 
> I have seen a new design for the food industry that is half round with a slot as a replacement for unistrut in SS so maybe that is the answer. In the mean time i might just borrow a spot weld timer and see what happens on some scrap. If it can tack the 4 small spots where the strut clamp grips it might work. The conduit is pvc coated ridgid (which may be the reason it loosens over time as the rubber between the strut and the conduit wears and compresses) So i do not think that a tiny weld will affect it.


What kind of straps are you using? If it's the PVC coated ones, there's your problem. All that PVC doesn't like gravity. There's a spray coating (I will edit this if I remember the name) that is listed to make rigid straps able to replace PVC coated. It allows for a much firmer grasp on the pipe! Just hang the straps from tie wire and spray them a good coat and dry overnight. I use bolts and nuts from PVC coated sets.


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## gpop

We are using SS straps, We tried pvc coated and they never seemed to fit correctly. 

If you consider how a strap works, The strap pulls the conduit tight against the unistrut. If you added a small wood spacer behind the conduit and tightened the clamp then removed it you would see 2 small indents in the wood where it made contact with the unistut. Now if you imagine its doing the same thing to the pvc coating add a little vibration and the pvc over time will deform which will lead to the clamp being loose. (also happens with most clamps used on pvc coated ridgid). It may take years but eventually the clamp slips and it looks bad.


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## Chops146

gpop said:


> We are using SS straps, We tried pvc coated and they never seemed to fit correctly.
> 
> If you consider how a strap works, The strap pulls the conduit tight against the unistrut. If you added a small wood spacer behind the conduit and tightened the clamp then removed it you would see 2 small indents in the wood where it made contact with the unistut. Now if you imagine its doing the same thing to the pvc coating add a little vibration and the pvc over time will deform which will lead to the clamp being loose. (also happens with most clamps used on pvc coated ridgid). It may take years but eventually the clamp slips and it looks bad.


Yep. Just reminded me of what we did on a vertical rack of 2". We cranked the straps down then pulled them off. Then we cut the PVC off where the strap marked and sprayed the coating on. Next day, we rehung it and strapped it with 2" EMT straps we'd sprayed the day before and cranked the heck out of them. That was only 3½ years ago, so can't tell you long term results.


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## Kawicrash

I've used a tek screw as a stop, but I guess that would be pretty tough on stainless.


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## QMED

I went through a welding program and there were a handful of union electricians there getting their AWS certs for welding as it was required for some nuke plant so they could weld their own supports.


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## sparkiez

Use nylocks. They would be more expensive than regular nuts, but would hold up over time and with the vibration.

https://en.wikipedia.org/wiki/Nyloc_nut


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## MDShunk

I use a fair bit of stainless strut, but it's the type that takes U-bolts for the conduit and not traditional Kindorf-type clamps, so slipping is not an issue.


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## gpop

MDShunk said:


> I use a fair bit of stainless strut, but it's the type that takes U-bolts for the conduit and not traditional Kindorf-type clamps, so slipping is not an issue.


I have a sales guy bringing some different style out. We will test it to see if it can handle the vibration with out cracking then go from there. 

The machines we use have a cam action and if they get in sync it will make the whole 60 x 100' deck jump.


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## MDShunk

This is the stuff we use. Grainger carries it. https://foodgradesolutions.com/

The benefit in a food environment is that it's self-draining.


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