penetration on butt jonts

[cozzie45]

Am currently welding 10mm plate and H irons together to make a shed. Am using about 230amps so plenty of heat. in fairly new to mig but all the welds are nice and clean and look fairly good. my biggest worry is if i am getting enough penetration. im welding the plates at both sides and also grinding back the metal at the end of the joint. So is there a special thickness of weld i need to put on, our is everything okay . also at what angle and movement rate gets the best penetrations

thanks

 

[zardoz]

Is there any way you can do a weld and then inspect it, by sawing it diagonally across the weld to give you a good view on the ammount of penetration and lack of bubbles etc. This is the best way. Once your sure you have a good setting and welding style for the work pieces then leave it.

 

[bc30se]

10 mm plate - 1.2 mm wire would be most proper here...

 

[zardoz]

In fact an Arc welder would be more appropriate. But with a 230Amp Mig and 0.8mm wire(i assume?) you will have to do multiple runs. Which i assume you are already doing ? Do you have any pictures you can show us ?

 

[Sparkey]

For a 230 amp mig he will at least have to use 1.0 mm wire...
As for the triple-pass welds they are normally only used on the connection between the h iron and plate that will be bolted to the floor.
As for the other welds, a single pass will do (with a nice and smooth weave)

ps: Zardoz is right! a few pics would clear up your questions a bit!

edit: ahh, sorry i misunderstood!
well, as for that type of weld, it depends on how much of a gap you have between the plates...sometimes if it's not too much you can do it in one pass (big weave) but if you for example v-prepped it you have to make more passes.....oh beautiful english language!

 

[malcolm]

It's a shed so unlikely to be subject to the same forces as a skyscraper (How big is the shed?) Full penetration is probably not necessary, but avoiding cold welds where the filler wire doesn't bond into the metal would still be important. Though 230 amps ought to be doing the trick. Like they say it won't actually be that many amps if the filler wire isn't thick enough, but I'd imagine it would still be enough with most filler wires.

Why are you grinding back the welds? You say it's a shed! I'd leave the weld be - extra stuff is extra strength.

Prepping the metal in a V shape can vastly improve penetration. Welding upwards rather than downwards helps too.

Post some photos - it's all academic until we see the welds.

 

[snowcat]

It's a shed so unlikely to be subject to the same forces as a skyscraper (How big is the shed?) Full penetration is probably not necessary, .

Hmmm shed could mean anything malc, used/have/will build some "sheds" in my time 80ft clear span, 20ft to the eves some, fairly important to get them right, I would weld them generally all single pass, early ones were stick welded, later MIG, Full pen forget it your cause the beams to warp like a banana, and create a hell of an undercut, UB are generally very thin walled for the structural strength and often wouldn't require a V prep, UC are a heavier section, although unlikely to be used as stanchions, and old fashioned RSJs some were the middle..

Like you say, tho.. pictures, plus section sizes, position and fitment also span etc etc.... will be needed before going into much detail.

 

[Hitch]

Most of the structural steelwork we do, welds are spec'd at 6mm fillets, or full penetration on butts.
Even on some of the very heafty stuff its only goes upto 8mm f/w.

230a machine with 0.8 wire will do 6mms, but will be a bit slow going. Where did this wire size thing come from anyway
ID be going for 1.00 wire given choice.


If your doing a basic building from UB's id guess 99% of the welds are fillets. No prep is normally needed, unless end plates havn't been allowed to fly past the size of the beam by 10mm each end.

Pretty rare a triple pass or even double pass is needed.


A few pics would be usefull.

 

[cozzie45]

okay lads i will get some pictures up later on in the day. I was grinding back the H irons into a V shape before welding as it my first shed. most of the plates ar being welded right around the H iron so i only have to penetrate 5mm on the H iron and as much as possible on the plate. the shed is 70 ish feet wide. with two outsid pillars and a mid pillar. the span between the mid pillar and out side pillar is about 28ft with the rest overhanging past the outside pillar. I am using 1.0m mig wire and my mig is a 260amp machine. plenty of power just a little slower than a biggie. Im pretty confident im my welding but will stick up pictures for the experts views. thanks

 

[cozzie45]

so here are a few pictures of the welds, sorry pics not the best

 

[cozzie45]

number 2

 

[Hitch]

Ah, simple end plates on beams with a haunch.
The only one i would prep would be the welds at the very ends of the plates.

My method would be to tack the plate and haunch on, when you get to the 2 welds, cut into it with a grinder (grinding disc) to form a V for the weld to sit in.

To save having to do that, i always allow 10mm extra on the top and bottom of the plate, so you get a fillet instead of a butt.
That also allows for some error on the size of the haunch.

I won't make an ounce of difference to the overall building as sheeting/purlins will hide it.

A couple of other observations though, looks like the weld could benefit from being a notch hotter. Perhaps the paint is hindering it a little.
The hole in the plate looks quite close to the weld, and also quite close to the edge of the plate. As a rule of thumb, holes are best off no more than 1.5x diameter of the hole away from the edge. What is it, an 18mm for a M16?

 

[snowcat]

Yep agree with Hitch on that, and defiantly don't make your holes too tight your only end up gassing them out on fitment, out a matter of interest why are you supporting the middle 70ft could easily be clear span??