Galvanized steel vs. regular steel

[sandyf]

On 12/31/2023 at 12:19 PM, itsari said:

Galvanized steel is 20 to 25 percent more than non galvanized steel . 

I don't think that is galvanised steel, looks more like zinc plated(Zintec).

Steel can be zinc coated in two ways, galvanising where the metal is hot dipped in molten zinc, or plated(Zintec) where the zinc is applied electrolytically. With hot dipping there is no control over the thickness of the coating whereas electrolysis gives a thin uniform coating.

https://keydifference.in/zintec-and-galvanised/

[Yellowtail]

Just now, Ralf001 said:

 

It wont be.

I do not disagree, but I don't to get in ten pages of nonsense because of something NASA does with and electron-bombardment process for coating vent-tubes on satellites or whatnot. 

[Ralf001]

Just now, Yellowtail said:

I do not disagree, but I don't to get in ten pages of nonsense because of something NASA does with and electron-bombardment process for coating vent-tubes on satellites or whatnot. 

 

I have been to all the major steel places in Thailand.

 

Infact we (the company I work for) import our own plate (150ton/month), have it  coiled to thickness, slit and then formed to RHS, SHS and Tube.

 

Never have I seen a pre-galvanised coil, thats make zero financial sense at this end of the end use market.

 

[Yellowtail]

3 minutes ago, sandyf said:

I don't think that is galvanised steel, looks more like zinc plated(Zintec).

Steel can be zinc coated in two ways, galvanising where the metal is hot dipped in molten zinc, or plated(Zintec) where the zinc is applied electrolytically. With hot dipping there is no control over the thickness of the coating whereas electrolysis gives a thin uniform coating.

https://keydifference.in/zintec-and-galvanised/

 

I would not bet either way on what's in the picture, but the coating thickness is generally very well controlled when galvanizing coil. It's much thicker than electro-galvanizing, but it is well controlled. 

[sometimewoodworker]

52 minutes ago, Yellowtail said:

I'd bet that the tubing in the photo was made by hot-rolled sheet that has been slit into coil, and then rollformed into shape. The welding would typically be done in between two of the final stations prior to the cutoff. 

Quite possible, as I said I don’t know the process. It’s just the available material locally. Also it demonstrates that @Yellowtail is probably talking about his area  as galvanised is generally easily available here.

 

53 minutes ago, Yellowtail said:

I can't really see the coating, but if it's coated inside and out, and the coating was not burned off the weld, then I would bet it was coated after cutoff. 

It is coated inside and out, and the coating was not burned off the weld, so you are probably correct

 

55 minutes ago, Yellowtail said:

If it is galvanized, and there any spangle, it's hot-dip. If it does not have any spangle, it could be either hot-dip or electro-galvanized. If there is no spangle and it’s smooth and shiny, it's probably electo. 

Electro would be my guess and the final forming done after plating.

 

56 minutes ago, Yellowtail said:

1.2mm wall thinness seems a bit thin for 4" seemless. 

I didn’t bother with my micrometer, just a cheap vernier calliper so I could be 0.1mm out but it is the wall thickness and the rolling former marks are reasonable distinct.

13 minutes ago, Ralf001 said:

14 minutes ago, Yellowtail said:

If the weld was burned off, it was rolled from galvanized coil. 

 

 

 

It wont be.

It isn’t 

[Yellowtail]

2 minutes ago, Ralf001 said:

 

I have been to all the major steel places in Thailand.

I have not. How many are there? 

2 minutes ago, Ralf001 said:

Infact we (the company I work for) import our own plate (150ton/month), have it  coiled to thickness, slit and then formed to RHS, SHS and Tube.

I do not understand coiled to thickness. Do you mean you import ingot have it rolled into sheet and coiled? 

 

What are RHS and SHS?

 

2 minutes ago, Ralf001 said:

Never have I seen a pre-galvanised coil, thats make zero financial sense at this end of the end use market.

Really? We bought all our coil galvanized. 

[sometimewoodworker]

36 minutes ago, sandyf said:

I don't think that is galvanised steel, looks more like zinc plated(Zintec).

Steel can be zinc coated in two ways, galvanising where the metal is hot dipped in molten zinc, or plated(Zintec)

That seems like a company trying to differentiate its product 

Quote

galvanizing is the process of applying a protective zinc coating to steel or iron, to prevent rusting.

If it is steel/iron with a zinc coating it is galvanised 

 

That there are different processes to coat the base material doesn’t change the fact that it is steel/iron with a zinc coating.

That Tata Steel is promoting its product with the trade name Zintec doesn’t change it from being galvanised steel.

That Tata Steel may have a more uniform product doesn’t change it from being galvanised steel.

Tata Steel’s product may be a better grade of galvanised steel and they are certainly trying to get away from using the name galvanised steel, but if it looks like a duck, walks like a duck, and quacks like a duck then it is a duck and calling it a swan makes no difference to the fact that it is a duck

[Lacessit]

1 hour ago, sandyf said:

I don't think that is galvanised steel, looks more like zinc plated(Zintec).

Steel can be zinc coated in two ways, galvanising where the metal is hot dipped in molten zinc, or plated(Zintec) where the zinc is applied electrolytically. With hot dipping there is no control over the thickness of the coating whereas electrolysis gives a thin uniform coating.

https://keydifference.in/zintec-and-galvanised/

The zinc coating thickness of hot dipped coil in a continuous coating line is controlled by high velocity air knives. Hot dipping of individual components is much more costly than forming sections from galvanized coil, the only form of thickness control is gravity. This is not necessarily a bad thing, as the thicker the zinc coating, the better the sacrificial protection is, plus there are no cut edges.

 

Electrolytic zinc coating is used in automotive applications. The coating thickness rarely gets above 30 g/sqm, which is fairly useless if the material is scratched during assembly. Thicker coatings by ED simply take too long to deposit on the substrate steel.

[sandyf]

18 hours ago, Yellowtail said:

 

I would not bet either way on what's in the picture, but the coating thickness is generally very well controlled when galvanizing coil. It's much thicker than electro-galvanizing, but it is well controlled. 

Quite. I worked in sheet metal fabrication for over 20 years and we used Zintec where ever possible. Unfortunately hollow section wasn't availabel zinc coated in those days.

I built my house here in 2009 and have done a quite a bit of work using using zinc coated hollow section, seen most of these display boards around the local merchants and the finish looks very much like I used to buy, but couldn't really be sure. Also used zinc coated roofing sheets and I would have said they were galvanised, the thicker coating gives a bit of a different colour.

[sandyf]

18 hours ago, sometimewoodworker said:

That seems like a company trying to differentiate its product 

If it is steel/iron with a zinc coating it is galvanised 

 

That there are different processes to coat the base material doesn’t change the fact that it is steel/iron with a zinc coating.

That Tata Steel is promoting its product with the trade name Zintec doesn’t change it from being galvanised steel.

That Tata Steel may have a more uniform product doesn’t change it from being galvanised steel.

Tata Steel’s product may be a better grade of galvanised steel and they are certainly trying to get away from using the name galvanised steel, but if it looks like a duck, walks like a duck, and quacks like a duck then it is a duck and calling it a swan makes no difference to the fact that it is a duck

People really love Google, don't they.

When talking to a steel merchant you have to use a language THEY understand,  Zintec(electrolytic) or Galvnised(hot dipped).

The MD goes quackers if you get it wrong.

[sandyf]

17 hours ago, Lacessit said:

The zinc coating thickness of hot dipped coil in a continuous coating line is controlled by high velocity air knives. Hot dipping of individual components is much more costly than forming sections from galvanized coil, the only form of thickness control is gravity. This is not necessarily a bad thing, as the thicker the zinc coating, the better the sacrificial protection is, plus there are no cut edges.

 

Electrolytic zinc coating is used in automotive applications. The coating thickness rarely gets above 30 g/sqm, which is fairly useless if the material is scratched during assembly. Thicker coatings by ED simply take too long to deposit on the substrate steel.

It's horses for courses. The thicker coating makes the steel more difficult to spot weld so there has to be a trade off and much of that type of fabrication is painted post op. We made industrial ovens and the casings were powder coated.

For anyone looking to use the steel for outside construction hot dipped would be the better choice if available, and why it helps to know the difference.

[Lacessit]

45 minutes ago, sandyf said:

It's horses for courses. The thicker coating makes the steel more difficult to spot weld so there has to be a trade off and much of that type of fabrication is painted post op. We made industrial ovens and the casings were powder coated.

For anyone looking to use the steel for outside construction hot dipped would be the better choice if available, and why it helps to know the difference.

There are also what are called weathering steels for outside applications. They form a patina of stable rust on the steel surface.

Not a good look if anyone wants something aesthetically pleasing, though.

 

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

 

[kickstart]

On 12/31/2023 at 10:24 AM, sometimewoodworker said:

As has been mentioned there is zero difference in strength between the same grade and thickness of galvanised vs mild steel.

However if it’s going to be welded take proper safety precautions as zinc smoke is toxic.

The thicker the steel the longer it will last before rust compromises the strength. Also though galvanised will have a much longer life before it rusts it will eventually rust once the zinc has been depleted.

And as I have found welding galvanized steel is not easy to weld , weld will not stick to it you have to take the galvanizing off first, as you said the gas is toxic and it spits so wear gloves.

With the above problem I have soaked the ends in caustic soda, that removes the galvanizing gives you clean metal to weld or use an angle grinder, you can re paint afterwards.

I have seen a lot of welded galvanized steel mainly pipe work some are very Dubus and not a strong weld. 

[Yellowtail]

32 minutes ago, kickstart said:

And as I have found welding galvanized steel is not easy to weld , weld will not stick to it you have to take the galvanizing off first, as you said the gas is toxic and it spits so wear gloves.

With the above problem I have soaked the ends in caustic soda, that removes the galvanizing gives you clean metal to weld or use an angle grinder, you can re paint afterwards.

I have seen a lot of welded galvanized steel mainly pipe work some are very Dubus and not a strong weld. 

How thick? We never had any difficulty MIG welding galvanized up 0.8 to 3.5mm using CO2. It burns the GA off without any issue, and I don't think the ash is any more toxic than welding stick. 

 

The spatter is a PITA

[Ralf001]

3 minutes ago, Yellowtail said:

It burns the GA off without any issue, and I don't think the ash is any more toxic than welding stick. 

 

The spatter is a PITA

 

Grind the gal off before welding, no toxic fumes and reduced spatter.

[Ralf001]

20 hours ago, Yellowtail said:

I have not. How many are there? 

I do not understand coiled to thickness. Do you mean you import ingot have it rolled into sheet and coiled? 

 

What are RHS and SHS?

 

Really? We bought all our coil galvanized. 

 

What does your company make from Gal coils ?

[jvs]

If you want the best quality have it all build with the size of steel you want.

Have everything put together with flanges and bolts.

When all done take apart and send away to be hot dipped galvanized.

Bolt it back together and you will have a move able carport that will last a very long time.

I did the same built with the kennels and it is just perfect.

 

[Yellowtail]

19 minutes ago, Ralf001 said:

 

What does your company make from Gal coils ?

In the Thailand plant we built fire, smoke, fire-smoke, balancing, backdraft and control dampers, and all the blade and frames are from galvanized coil. Virtually all the spiral duct you see comes from galvanized coil, and most high-volume steel HVAC products have at least some parts from coil. 

 

Most all the galvanized building material comes from coil. 

 

[sometimewoodworker]

1 hour ago, Ralf001 said:

 

Grind the gal off before welding, no toxic fumes and reduced spatter.

That is impossible to do on the inside of anything but circular pipe so the toxic fumes are a given, though I haven’t noticed that much splatter using 75/25 but I do wire brush most of my welds and use an organic filter mask to control the zinc fumes.

 

so far I haven’t tried anything much that I haven’t brushed the zinc off so can’t comment on how easy it is to weld without proper prep, but I will give it a try on a sample.

[Ralf001]

47 minutes ago, Yellowtail said:

In the Thailand plant we built fire, smoke, fire-smoke, balancing, backdraft and control dampers, and all the blade and frames are from galvanized coil. Virtually all the spiral duct you see comes from galvanized coil, and most high-volume steel HVAC products have at least some parts from coil. 

 

Most all the galvanized building material comes from coil. 

 

 

 

Ahh right... Thin sheet HVAC ducting systems, different kettle of fish than structural steels and one I have had no exposure to.

 

[Ralf001]

15 minutes ago, sometimewoodworker said:

That is impossible to do on the inside of anything but circular pipe so the toxic fumes are a given, though I haven’t noticed that much splatter using 75/25 but I do wire brush most of my welds and use an organic filter mask to control the zinc fumes.

 

so far I haven’t tried anything much that I haven’t brushed the zinc off so can’t comment on how easy it is to weld without proper prep, but I will give it a try on a sample.

 

What is 75/25 ?

 

I personally refuse to weld gal steel these days.

 

[Artisi]

1 hour ago, Ralf001 said:

 

What is 75/25 ?

 

I personally refuse to weld gal steel these days.

 

I stopped welding gal steel 60 years unless the gal in the weld area was removed from the weld area.

[sometimewoodworker]

2 hours ago, Ralf001 said:

 

What is 75/25 ?

 

I personally refuse to weld gal steel these days.

 

You probably never use gas for MIG then as it is the standard MIG gas mix for most steel, pure CO₂ is cheaper but promotes splatter, since I only do a little the cost savings are virtually irrelevant to me, since I don’t use stainless pure argon is not of interest.

[Ralf001]

47 minutes ago, sometimewoodworker said:

You probably never use gas for MIG then as it is the standard MIG gas mix for most steel, pure CO₂ is cheaper but promotes splatter, since I only do a little the cost savings are virtually irrelevant to me, since I don’t use stainless pure argon is not of interest.

 

Hahahahah, never used mig gas hahahhahahaha, them wood fumes have <deleted> your brain !

 

We weld Finished product per day through 20 Robot and 35 manual weld bays.

We consume 150 ton of steel a month.

We consume 8 ton of mig wire a month.

We blend CO2 and argon onsite.

 

Dont even try preach to me about MIG gas, the clueless one is you, not me.

[Yellowtail]

1 hour ago, sometimewoodworker said:

You probably never use gas for MIG then as it is the standard MIG gas mix for most steel, pure CO₂ is cheaper but promotes splatter, since I only do a little the cost savings are virtually irrelevant to me, since I don’t use stainless pure argon is not of interest.

Your mix if fine for stainless, just use flux-core wire. 

[sometimewoodworker]

1 hour ago, Ralf001 said:

 

Hahahahah, never used mig gas hahahhahahaha, them wood fumes have <deleted> your brain !

 

We weld Finished product per day through 20 Robot and 35 manual weld bays.

We consume 150 ton of steel a month.

We consume 8 ton of mig wire a month.

We blend CO2 and argon onsite.

 

Dont even try preach to me about MIG gas, the clueless one is you, not me.

So why are you asking what 75/25 is if you are so all fired up about your capabilities how are you so ignorant of the most basic standard mix. Clueless, patronising and probably why you won’t weld galvanised now, is your cognitive capacity really that bad now? Or are you just making a poor attempt at being a troll? Or an even worse attempt at joking?

[sometimewoodworker]

1 hour ago, Yellowtail said:

Your mix if fine for stainless, just use flux-core wire. 

I have a small bottle of Argon if I ever get the urge to get into SS welding and I would probably get a TIG torch for my welder for SS rather than using flux-core, I still have an unopened 5kg spool of flux-core if I ever need to do anything outside, but can’t see me doing anything with SS.

[sandyf]

21 hours ago, Lacessit said:

There are also what are called weathering steels for outside applications. They form a patina of stable rust on the steel surface.

Not a good look if anyone wants something aesthetically pleasing, though.

 

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

 

I have used a fair bit of 25mm x 1mm sq hollow section in the garden to prop up shrubs, some of it has been out there for over 10 years now and weathered well enough for me, still looks like just out of the warehouse. Unfortunately I can't say the same for the galv roofing sheets, after about 3 years rust holes started to appear. The coloured coated ones we got about 8 years ago have lasted an awful lot better. With those I think the paint may have gone on a zinc coating but when we wanted more Global said they were no longer available.

Built these cat cages back in 2016.

[Lacessit]

3 minutes ago, sandyf said:

I have used a fair bit of 25mm x 1mm sq hollow section in the garden to prop up shrubs, some of it has been out there for over 10 years now and weathered well enough for me, still looks like just out of the warehouse. Unfortunately I can't say the same for the galv roofing sheets, after about 3 years rust holes started to appear. The coloured coated ones we got about 8 years ago have lasted an awful lot better. With those I think the paint may have gone on a zinc coating but when we wanted more Global said they were no longer available.

Built these cat cages back in 2016.

There is no way you should have rusting on galvanized sheet after only three years, there is something wrong. Are the holes random, or in a pattern? What is the coating mass ( g/sqm )?

How are the sheets fixed? Look for metal swarf or rivets on the rooftop.

Washers heavy in carbon have been known to cause corrosion.

If there is any repeat any copper in contact with the roof, either as a sheet or swarf, that would explain what you are seeing.

 

[sandyf]

5 minutes ago, Lacessit said:

There is no way you should have rusting on galvanized sheet after only three years, there is something wrong. Are the holes random, or in a pattern? What is the coating mass ( g/sqm )?

How are the sheets fixed? Look for metal swarf or rivets on the rooftop.

Washers heavy in carbon have been known to cause corrosion.

If there is any repeat any copper in contact with the roof, either as a sheet or swarf, that would explain what you are seeing.

 

Different cage that I built  just a few years ago. The rust is just random patches a couple of inches in dia and not anywhere near fixings. No idea on the coating thickness, had to buy what Global had available at the time. Suspect they were just badly coated, unless something coming off the trees affected the coating.

Unfortunately distance is a factor when driving with roofings sheets in the pickup so Global being just down the road is usual choice.